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CHARACTERISTICS OF PERVIOUS CONCRETE
FOR PAVEMENT USE
LIM EMIKO
(B.Eng (Hons), M.Eng, National University of Singapore)
A THESIS SUBMITTED
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
DEPARTMENT OF CIVIL AND ENVIRONMENTAL
ENGINEERING
NATIONAL UNIVERSITY OF SINGAPORE
2016
i
DECLARATION
I hereby declare that the thesis is my original work and it has been written by
me in its entirety. I have duly acknowledged all the sources of information
which have been used in the thesis.
This thesis has also not been submitted for any degree in any university
previously.
30th June 2016
ii
ACKNOWLEDGEMENTS
I would like to express my utmost appreciation and gratitude to my
supervisors, Professor Tan Kiang Hwee and Professor Fwa Tien Fang for their
invaluable guidance, tutelage, help and encouragement throughout the
research. I also extend my heartfelt gratitude to Professor S.P. Lim from the
Mechanical Engineering/Applied Mechanics Group for his tutelage and help.
I would extend my heartfelt appreciation to Professor Zhang Min
Hong, Assistant Professor Raymond Ong, members of my Ph.D. committee
and Professor David Chua for their insightful and helpful recommendations in
improving my research. My sincere thanks also go to Professor Chew Chye
Heng from the Mechanical Engineering Group for the specialised knowledge
he provided.
Thanks are also accorded to Wei Leng, Mr Foo, Mr Goh, Mr Farouk
and Teresa of the Transportation Engineering Laboratory; Stanley, Mr Koh,
Mr Ang, Mr Ow, Mr Kamsan, Mr Ishak and Mr Choo of the Structural
Laboratory and Mr Cheng, Priscilla and Amy of the Mechanical Engineering
Laboratory for their kind assistance and full support in the course of this
research. Thanks are also addressed to my colleagues and friends, Dr Zhang
Lei, Dr Ju Fenghua, Dr Yang Jiasheng, Maggie, Fu Rao, Yin Lu, Yujie, and
Akshay for their kind help and friendship.
Finally, I am especially grateful to my parents for their infinite care,
encouragements and support. This work is dedicated to my parents.
iii
Table of Contents
ACKNOWLEDGEMENTS ............................................................................... ii
SUMMARY ...................................................................................................... vi
LIST OF TABLES ......................................................................................... viii
LIST OF FIGURES ........................................................................................... x
CHAPTER 1 INTRODUCTION ..................................................................... 15
1.1 General ................................................................................................... 15
1.1.1 Advantages and limitations ............................................................. 16
1.1.2 Applications ..................................................................................... 16
1.2 Significance of current study ................................................................. 19
1.3 Objectives and scope of research ........................................................... 20
1.3.1 Physical and mechanical properties ................................................. 20
1.3.2 Clogging characteristics .................................................................. 21
1.3.3 Sound absorption characteristics ..................................................... 21
1.4 Structure of thesis ................................................................................... 22
CHAPTER 2 LITERATURE REVIEW .......................................................... 23
2.1 Physical and mechanical properties of pervious concrete ...................... 23
2.1.1 Effect of mixture proportion ............................................................ 23
2.1.1.1 Compressive strength ............................................................... 25
2.1.1.2 Flexural Strength ...................................................................... 26
2.1.1.3 Porosity .................................................................................... 26
2.1.1.4 Permeability ............................................................................. 27
2.1.2 Use of supplementary materials in pervious concrete mixes .......... 27
2.1.3 Fiber reinforcement for pervious concrete ...................................... 29
2.2 Clogging characteristics of pervious concrete ....................................... 31
2.2.1 Effect of clogging materials ............................................................ 32
2.2.2 Service life of pervious concrete pavements with clogging ............ 34
2.3 Sound absorption properties of pervious concrete ................................. 35
2.3.1 Acoustic properties of pervious concrete pavements ...................... 36
2.4 Target performances ............................................................................... 37
2.5 Summary ................................................................................................ 38
iv
CHAPTER 3 PHYSICAL AND MECHANICAL PROPERTIES OF
PERVIOUS CONCRETE ................................................................................ 49
3.1 Test programme...................................................................................... 49
3.1.1 Materials .......................................................................................... 51
3.1.2 Test specimens ................................................................................. 52
3.1.3 Test methodology ............................................................................ 52
3.1.4 Workability ...................................................................................... 54
3.2 Test results and discussion ..................................................................... 55
3.2.1 Unreinforced pervious concrete....................................................... 55
3.2.2 Steel fiber reinforced pervious concrete .......................................... 57
3.3 Summary ................................................................................................ 60
CHAPTER 4 CLOGGING CHARACTERISTICS OF PERVIOUS
CONCRETE .................................................................................................... 85
4.1 Evaluation of clogging characteristics and porosity .............................. 85
4.1.1 Measurement of permeability coefficient ........................................ 86
4.1.2 Clogging procedure ......................................................................... 86
4.1.3 Clogging materials ........................................................................... 87
4.1.4 Measurement of porosity ................................................................. 88
4.2 Pavement mixtures ................................................................................. 89
4.2.1 Pervious Concrete Mixtures ............................................................ 89
4.2.2 Porous Asphalt Mixtures ................................................................. 89
4.3 Test results and discussion ..................................................................... 90
4.3.1 Effect of different clogging materials .............................................. 90
4.3.2 Comparison of permeability ............................................................ 91
4.3.3 Comparison of clogging behaviour ................................................. 92
4.3.4 Effect of steel fibers on clogging behaviour .................................... 96
4.4 Evaluation of clogging potential of porous materials ............................ 97
4.4.1 Analysis of permeability reduction due to clogging ........................ 99
4.5 Summary .............................................................................................. 100
CHAPTER 5 SOUND ABSORPTION CAPACITY OF PERVIOUS
CONCRETE .................................................................................................. 120
5.1 Experimental Program.......................................................................... 121
v
5.1.1 Pavement materials ........................................................................ 121
5.1.2 Test specimens and conditioning ................................................... 122
5.1.3. Acoustic absorption measurement ........................................... 123
5.2 Test results and discussion ................................................................... 125
5.2.1 Effect of different road materials (Test Series A) ......................... 125
5.2.2 Effect of porosity (Test Series B) .................................................. 127
5.2.3 Effect of thickness (Test Series C) ................................................ 128
5.2.4 Effect of clogging (Test Series D) ................................................. 129
5.3 Sound pressure level dB(A) ................................................................. 131
5.4 Summary .............................................................................................. 134
CHAPTER 6 CONCLUSION........................................................................ 179
6.1 Review of work done ........................................................................... 179
6.2 Summary of main findings ................................................................... 179
6.2.1 Physical and mechanical properties of pervious concrete ............. 179
6.2.2 Clogging characteristics of pervious concrete ............................... 180
6.2.3 Sound absorption capacity of pervious concrete ........................... 180
6.3 Recommendations for further research ................................................ 181
LIST OF PUBLICATIONS ........................................................................... 183
REFERENCES .............................................................................................. 185
ANNEX A: Residual Normality Analysis ..................................................... 211
ANNEX B: Statistical analysis using T-Test: Two samples assuming ...............
unequal variances for selected mixes ............................................................. 220
vi
SUMMARY
Pervious concrete may be used in road pavements to prevent flash
flooding and provide wet-weather skid resistance due to its porous nature.
Besides adequate strength, it must possess good clogging and sound
absorption characteristics. This study investigated the use of steel fibers in
enhancing the flexural strength of pervious concrete without compromising its
permeability and porosity. To meet these requirements, the target strength of
the pervious concrete was 3.5 MPa and the permeability and porosity were 10
mm/s and 20% or higher respectively.
To achieve a highly permeable and porous pavement with reasonable
compressive and flexural strengths, the CA/C ratio should be in the region of
4.25, water-cement ratio of around 0.3 and cement in the range of 360 kg/m3
to 400 kg/m3. However without the use of steel fibers, target performances
would be difficult to achieve.
Results showed that fiber inclusion up to 2.25% by volume met the
target performances and a minimum dosage of 1.5% was recommended for
practical mix design.
At porosities ranging from 10% to 25%, pervious concrete provided
better clogging characteristics than porous asphalt. Adding steel fibers did not
affect the performance. Pervious concrete was found to possess better
clogging resistance than porous asphalt mixtures having the same level of
porosity.
The sound absorption capacity of pervious concrete was compared to
those of normal, steel fiber-reinforced concrete, lean concrete, porous asphalt,
vii
open-graded asphalt and dense asphalt. Pervious concrete with or without steel
fiber was found to achieve a significant overall sound pressure reduction of
more than 4.5 dB(A) when compared to normal weight concrete and dense
graded asphalt mixes.
When fully clogged, pervious concrete and porous asphalt had
comparable overall sound pressure levels. Comparing the before and after
effects of clogging, the sound absorption capacities of pervious concrete and
porous asphalt were not compromised and a minor increase of about 1 dB(A)
was noted.
In summary, this research has (a) provided a new pervious concrete
mix design that meets the target performances of having reasonable flexural
strength, permeability and porosity for pavement use, (b) recommended
porosity level for good drainage performance with satisfactory clogging
resistance and (c) evaluated and compared expected sound absorption
properties of the recommended pervious concrete mix design with other
existing road materials.
viii
LIST OF TABLES
Table 2.1 Typical ranges of material proportions in pervious concrete .......... 39
Table 2.2 Pervious concrete target requirements ............................................. 40
Table 3.1 Types of tests and various test samples ........................................... 61
Table 3.2(a) Mix proportion design (Part 1) .................................................... 62
Table 3.2 (b) Mix proportion design (Part II) .................................................. 62
Table 3.3 (a) Gradation of small and large coarse aggregates ......................... 63
Table 3.4 Properties of steel fibers .................................................................. 63
Table 3.5: Physical and mechanical properties of pervious concrete .............. 64
Table 3.5: Physical and mechanical properties of pervious concrete (cont’d) 65
Table 3.6 Summary of test results.................................................................... 66
Table 3.6 Summary of test results (Cont’d) ..................................................... 67
Table 3.7 Recommended steel fiber dosages ................................................... 67
Table 4.1 Mixture design of pervious concrete ............................................. 103
Table 4.2 Aggregate gradations and mix composition of porous asphalt mix
........................................................................................................................ 104
designs............................................................................................................ 104
Table 4.3 Porosity and permeability coefficient of pervious concrete and .... 105
porous asphalt specimens ............................................................................... 105
Table 4.4 Rates of increase of permeability coefficient with porosity for ..... 106
porous asphalt and pervious concrete mixtures ............................................. 106
Table 4.5 Measured porosity of steel fiber pervious concrete specimens ..... 107
Table 5.1 Sound Absorption Test Program.................................................... 136
Table 5.1 Sound Absorption Test Program (Cont’d) ..................................... 137
Table 5.2 Gradation analysis for coarse and fine aggregates ......................... 138
Table 5.3 Mix proportions of concrete samples............................................. 139
Table 5.4 Aggregate gradation and mix composition of asphalt mix designs
........................................................................................................................ 140
Table 5.5 Measured sound absorption coefficients for Series A with different ..
material types ................................................................................................. 141
ix
Table 5.6 Porosity of specimens for Series B on materials type ................... 145
Table 5.7 Peak sound absorption coefficient for pervious concrete and porous .
asphalt specimens for Series B test with different porosities ........................ 145
Table 5.8 Measured sound absorption coefficients for Series C with different...
thicknesses of pavement layer ....................................................................... 146
Table 5.9 Target porosity and measured porosity of the samples for Series D ...
with different degrees of clogging ................................................................. 149
Table 5.10 Measured sound absorption coefficients for Series D with different
degrees of clogging ........................................................................................ 150
Table 5.11 Peak α values for different porosity and the frequency that they 155
occur at for clogging series D ........................................................................ 155
Table 5.12 1/3 octave frequency sound pressures for all test specimens (Series
........................................................................................................................ 156
A, B, C and D) ............................................................................................... 156
Table 5.13 Overall sound pressures for all specimens (Series A, B, C and D)
........................................................................................................................ 159
x
LIST OF FIGURES
Figure 2.1 Effect of cement content ................................................................. 44
Figure 2.2 Effect of coarse aggregate content ................................................. 45
Figure 2.3 Effect of water-cement ratio ........................................................... 46
Figure 2.4 Effect of fiber dosage ..................................................................... 47
Figure 2.5 Compressive strength (MPa) versus porosity (%) .......................... 48
Figure 2.6 Flexural strength (MPa) versus permeability (mm/s) ..................... 48
Figure 3.1 Steel 3D-S, 3D-L, 4D and 5D hook-end fibers (Dramix) .............. 68
Figure 3.2 Test samples ................................................................................... 68
Figure.3.3 Constant-head permeability test set-up .......................................... 69
Figure 3.4 Volume measure with fresh pervious concrete for density test ...... 69
Figure 3.5 Ball test for workability of pervious concrete (Sonebi and Bassuoni,
2013) ................................................................................................................ 70
Figure 3.6 Slump test ....................................................................................... 70
Figure 3.7: Physical and mechanical properties of pervious concrete ............. 71
Figure 3.8 Effect of coarse aggregate size in unreinforced pervious concrete 75
Figure 3.9 Effect of water-cement ratio in unreinforced pervious concrete .... 76
Figure 3.10 Effect of cement content in unreinforced pervious concrete ........ 77
Figure 3.11 Compressive strength of fiber reinforced pervious concrete ........ 78
Figure 3.12 Flexural strength results of fiber reinforced pervious concrete .... 79
Figure 3.13 Permeability results of fiber reinforced pervious concrete ........... 80
Figure 3.14 Porosity results of fiber reinforced pervious concrete .................. 81
Figure 3.15 Effect of fiber length in fiber reinforced pervious concrete ......... 82
Figure 3.16 Flexural strength versus permeability of test mixes ..................... 83
Figure 3.17 Compressive strength versus porosity of test mixes..................... 83
Figure 3.18 Relationship between flexural strength and porosity of pervious 84
concrete ............................................................................................................ 84
Figure 3.19 Relationship between flexural strength and permeability of ............
pervious concrete ............................................................................................. 84
Figure 4.1 Gradations of common clogging materials on Singapore roads ... 108
xi
Figure 4.2 Permeability versus clogging stages of pervious concrete and .... 109
porous asphalt at 20% porosity. ..................................................................... 109
Figure 4.3 Relationship between porosity and permeability coefficient ....... 110
Figure 4.4 Effect of clogging cycle on permeability coefficients .................. 111
Figure 4.5 Comparison of permeability deterioration curves of porous asphalt..
and pervious concrete mixtures ..................................................................... 112
Figure 4.6 Pervious concrete and porous asphalt mixes of different porosities ..
after clogging effect ....................................................................................... 113
Figure 4.7 Clogged fiber reinforced pervious concrete specimen ................. 114
Figure 4.8 Clogging characteristics of steel fiber reinforced pervious concrete .
specimens ....................................................................................................... 114
Figure 4.9 Average soil retained for pervious concrete and porous asphalt ........
samples with different porosities ................................................................... 115
Figure 4.10 Permeability deterioration factor (αc) ......................................... 116
Figure 4.11 Permeability deterioration factor (αc) for pervious concrete and .....
porous asphalt specimens ............................................................................... 117
Figure 4.12 Permeability deterioration factor (αc) for unreinforced pervious .....
concrete and fiber reinforced pervious concrete specimens .......................... 119
Figure 5.1 Sample holder for acoustic absorption tests ................................. 160
Figure 5.2 Pervious concrete samples – (a) 0% clogged; (b) 25% clogged; .......
(c) 50% clogged; (d) 75% clogged; (e) 100% clogged .................................. 161
Figure 5.3 Porous asphalt samples – (a) 0% clogged; (b) 25% clogged; ............
(c) 50% clogged; (d) 75% clogged; (e) 100% clogged .................................. 162
Figure 5.4 (a) Impedance tube setup for frequencies 100 -500 Hz;.....................
(b) Impedance tube setup for frequencies 600 - 2000 Hz .............................. 163
Figure 5.5 Low and high frequency sound waves ......................................... 164
Figure 5.6 Sound absorption coefficient values for eight road materials ...... 164
Figure 5.7 Sound absorption coefficient values for (a) pervious concrete (b) .....
porous asphalt at varying porosities in Test Series B .................................... 165
Figure 5.8 Comparison of sound absorption coefficient values for pervious ......
concrete and porous asphalt at individual target porosities in Test .....................
Series B .......................................................................................................... 166
xii
Figure 5.9 Sample thicknesses ....................................................................... 168
Figure 5.10 Sound absorption coefficient values for pervious concrete and .......
porous asphalt at different thicknesses in Test Series C ................................ 169
Figure 5.11 Comparison of pervious concrete and porous asphalt by thickness .
in Test Series C .............................................................................................. 170
Figure 5.12 Sound absorption coefficient values for pervious concrete and . 172
porous asphalt at varying clogging percentages in Test Series D .................. 172
Figure 5.13 (a) Sound pressure levels dB(A) at 1/3 octave frequencies and (b) .
overall sound pressure levels dB(A) for different road materials in Test Series
A ..................................................................................................................... 173
Figure 5.14 Sound pressure levels dB(A) at 1/3 octave frequencies for (a) ........
pervious concrete (b) porous asphalt and (c) overall sound pressure levels
dB(A) for pervious concrete (PC) and porous asphalt (PA) of varying porosity
........................................................................................................................ 174
Figure 5.15 (a) Sound pressure levels dB(A) at 1/3 octave frequencies and (b) .
overall sound pressure levels dB(A) for pervious concrete (PC) and porous
asphalt (PA) of varying thickness in Test Series C ........................................ 176
Figure 5.16 Sound pressure levels dB(A) at 1/3 octave frequencies for (a) ........
pervious concrete (b) porous asphalt and (c) overall sound pressure levels
dB(A) for pervious concrete (PC) and porous asphalt (PA) of varying clogging
percentage in Test Series D ............................................................................ 177
xiii
LIST OF SYMBOLS
A cross-sectional area;
Aair mass of dry specimen in air, (g);
B mass of specimen immersed in water (g);
D density (unit weight) of concrete (kg/m3);
df fibre diameter (m);
dp mean particle diameter (m);
g acceleration due to gravity (m/s2),
H constant water head (mm);
i hydraulic gradient;
k permeability coefficient (mm/s);
k0 initial permeability coefficient (mm/s);
L thickness (mm);
mc mass of clogging material retained in specimen (kg);
Mc mass of the container filled with concrete (kg);
Mm mass of the container (kg);
np porosity (%);
n experimental coefficient;
N total number of centre frequencies;
PA(t) instantaneous A-weighted SPL (Pa);
pref reference sound pressure level (SPL) = (20 x 10-6
Pa);
Q amount of water collected (mm3);
sv volumetric specific surface area of permeable medium (m-1
);
T specified time interval (sec);
xiv
t test duration(sec);
V volume (m3);
Vc clogging material retained (m3),
Vm volume of the container (m3);
Vr total void ratio (%);
VT volume of specimen (m3);
W1 weight of sample immersed in water (kg);
W2 weight of sample in air (kg);
WA % binder (asphalt);
Wagg weight of aggregate (g);
Wbit weight of bitumen (g);
WA’ A-weighted sound power level (PWL);
Wref reference sound power level (PWL) = (10-12
watts);
α sound absorption coefficient (empirical constant);
αc permeability deterioration rate (empirical constant);
ηw viscosity of water (kg/m.s);
λ shape factor function of tortuosity of medium;
ρc density of clogging material (kg/m3);
ρw density of water (kg/m3);
σ specific deposit of clogging material.
15
CHAPTER 1 INTRODUCTION
1.1 General
Urbanization is increasing with the growth in world population. As
cities expand, the drainage networks in many cities are unable to handle the
higher runoff due to the increased built up areas. As such, flooding has
become a common occurrence. A good alternative is to use pervious concrete
as road pavement material to supplement the passive storm water management
system.
Pervious concrete is described typically as a near zero-slump, open
graded material consisting of Portland cement, coarse aggregates with little or
no fine aggregates, admixtures and water (ACI Committee Report 522, 2010).
The use of pervious concrete in pavements and housing dated back to the 18th
century in Europe as it was cheaper compared to conventional concrete due to
the lesser amount of cement used during its construction (Chopra et al., 2007).
In the 1990s and early 2000s, pervious concrete was used as a wearing course
on high‐speed roads in Europe and Japan. Pervious concrete also served as a
noise reducer and safety measure. The interconnected void network in
pervious concrete reduces noise and removes water from the vehicle wheel
path thus improving skid resistance and effectively improving road safety.
(Environmental protection agency, 2008; ISU-FHWA-ACPA, 2006 and
Kagata et al., 2004).
The connected pores in pervious concrete range from 2 mm to 8 mm in
size and allow water to pass through easily. The void content could range from
15% to 35% and typical compressive and flexural strengths are between 2.8 to
16
28 MPa and 0.6 to 4.8 MPa respectively. Pervious concrete is weaker in
strength as compared to normal weight concrete but provides better drainage.
The drainage rate of pervious concrete pavement varies with aggregate size
and density of the mixture and is typically between 1.4 mm/s to 12.2 mm/s.
1.1.1 Advantages and limitations
Pervious concrete is increasingly used in the United States because of
its various environmental benefits such as controlling storm water runoff,
restoring groundwater supplies and reducing water and soil pollution (Youngs,
2005; Tennis et al., 2004 and Kajio, 1998). Further advantages of a pervious
concrete pavement are its ability to decrease the effect of heat-island as
surface temperature is lowered due to increased evaporation of water;
increased skid resistance and surface friction; reduction in tire noise as it
absorbs the noise and dissipates it within the pavement. It can be considered a
green and recyclable building material (Kevern et al., 2009; Haselbach et al.,
2006; Ferguson, 2005; US EPA, 1999 and Bean et al., 2007).
Some disadvantages of pervious concrete include its inability to handle
heavy traffic loadings due to its low compressive and flexural strengths. Also
the drainage function of pervious concrete may be lost due to clogging over
time and this requires effective and timely cleaning. Such timely maintenance
and cleaning of the pervious concrete may be costly. (Kevern et al., 2009;
Haselbach et al., 2006; US EPA, 1999 and Balades et al., 1995).
1.1.2 Applications
Pervious concrete has been used in a wide range of applications not
only in parking lots, road shoulders, minor pavements, base course for streets,
17
roads, driveways and airports, surface course for parks and tennis courts; but
also for greenhouse floors to keep the floor free of standing water; thermal
insulation applications; walls and floors where better acoustic characteristics
are desired; bridge embankments, structures and seawalls, drains as well as
sewage treatment plant sludge beds (ACI Committee report 522, 2010).
(a) Surface course - Pervious concrete is used as a surface course for
parking lots and minor road strips to a large extent in the U.S. Many parking
lots in Florida consist of a pervious concrete surface course, which is useful as
Florida frequently encounters heavy storms that cause a quick accumulation of
large amounts of stormwater. The use of pervious concrete reduces runoff
volume; designers prefer the stormwater to be retained on-site to recharge the
groundwater system and the cost effectiveness of using pervious concrete over
conventional pavements is greatly enhanced with the elimination of storm
sewers (ACI Committee report, 2010).
(b) Parking lots - Pervious concrete has also been used in parking lots
in the central Florida area as early as the 1970s (Medico, 1975). The
Environmental Protection Agency (EPA) has adopted a policy that
recommends the use of pervious pavements as part of their Best Management
Practices (BMPs) as a way for communities to mitigate the problem of
stormwater runoff. Pervious concrete parking lots have also been selected as
an integral solution to the problem of hot pavements in the Cool Communities
Program. The air temperature over pervious parking lots is generally cooler
than asphalt. Pervious concrete parking lots also reduce snow and ice build-up
and are considered a non-pollutant to the environment. Schaefer et al., (2008)
reported that pervious concrete has been used as a construction vehicle
18
parking area test section in Sioux City, Iowa; visitor parking area at North
Liberty, Iowa and handicapped parking area at the Iowa Great Lakes Maritime
Museum. The design thickness for pervious concrete pavements is 125 mm to
300 mm for normal concrete parking lots.
(c) Base and subbase - Pervious concrete for roadways is usually used
as a drainable base or sub-base material, and as a roadway surface or friction
course. Although good drainage characteristics are derived, strength
requirements may vary depending on the location of the material in the
pavement section. The design thickness for pervious concrete roadway
pavements is between 150 mm to 300 mm. Maynard (1970) noted that bonded
overlays as thin as 50 mm have been used.
A pervious concrete base drains water that would normally accumulate
beneath a pavement. This type of construction helps to reduce pumping of
subgrade materials that could lead to the failure of the pavement. The States of
California, Illinois, Oklahoma and Wisconsin in U.S have standard
specifications for constructing drainable bases and edge drains using pervious
concrete (Mathis, 1990). Pervious concrete in these applications is usually of
lower compressive strengths at around 7 MPa or less and is used together with
a nonwoven geotextile fabric.
(d) Other applications - Pervious concrete shoulders have been used in
France to reduce pumping beneath concrete pavements. Air-entraining
admixtures are used to increase resistance to freezing and thawing. Porosities
of about 15 to 25 % have been found to nearly eliminate the risk due to
freezing unless the concrete is allowed to become saturated with water.
19
Compressive strengths are often less than 14 MPa at 28 days (ACI Committee
Report 522, 2010).
1.2 Significance of current study
Due to the wet-tropical climate and rapidly increasing built-up areas,
many urban cities like Singapore are subjected to flash floodings during heavy
downpour. The use of pervious concrete pavements (Chan et al., 2012) would
effectively drain away rainwater as well as provide a temporary storage for
flood water during high tides.
The major requirements for pervious concrete to be used in major road
pavements are adequate flexural strength, porosity and permeability. However
because permeability and porosity decrease with increasing flexural strength,
the challenge in pervious concrete mix proportioning is in achieving a balance
between an acceptable permeability and flexural strength. The inclusion of
fibers in pervious concrete is an effective step in preventing the expansion of
micro-cracks and to increase the flexural strength of pervious concrete (Seung
et al., 2012).
The first part of this research will therefore investigate the use of steel
fibers having different hooked-end configurations and in varying dosages in
pervious concrete, with a focus on flexural and compressive strengths,
porosity and permeability. Target satisfactory performances are: a flexural
strength exceeding 3.5 MPa, porosity more than 20% and permeability above
10 mm/s. The target strength follows the minimum requirement for rigid
pavement according to AASHTO (1993).
20
The second part of the study will focus on the clogging characteristics
of pervious concrete. Because of the large pore sizes, clogging of pervious
concrete due to dust and debris when in service would be a major concern.
The permeability and clogging characteristics of pervious concrete mixtures
were also compared with porous asphalt mixes.
The third part of the study will evaluate the sound absorption capacity
of pervious concrete. Pervious concrete has been noted to produce a quieter
environment; however, little study has been done in this respect. A
comparison with other road pavements materials, that is, normal weight
concrete, lean concrete; dense asphalt, open-graded and porous asphalt was
carried out.
1.3 Objectives and scope of research
The main objective of this research is to investigate the use of pervious
concrete for road pavements with focus on flexural strength, porosity and
permeability. Steel fiber reinforced pervious concrete would be explored. The
second objective is to evaluate the clogging performance and the third
objective to assess the sound absorption capacity of pervious concrete. The
scope of work is as follows.
1.3.1 Physical and mechanical properties
The effect of mix proportion and steel fibers on the compressive and
flexural strengths and porosity and permeability of pervious concrete was
studied. Test parameters included the coarse aggregate size, cement content,
21
water-cement ratio, type and dosage of steel fibers. The steel fibers had
hooked ends of different configurations.
1.3.2 Clogging characteristics
The effect of clogging on the permeability of pervious concrete was
investigated and compared to porous asphalt. Four types of clogging materials
were first analysed; they were residual soil, fine to medium sand, fine to
coarse sand and medium to coarse sand. The type of sand most detrimental to
the clogging of pervious concrete and porous asphalt was used for further
tests. The experimental programme considered four target porosity levels
which covered the likely range that a porous pavement material would
undergo through its entire useful service life. Empirical equations relating the
permeability and porosity were established. The effect of clogging on steel
fiber reinforced pervious concrete was also examined.
1.3.3 Sound absorption characteristics
The sound absorption characteristics of pervious concrete was
investigated and compared with other pavement materials including normal
weight concrete; lean concrete; porous asphalt, open-graded and dense asphalt
mixtures. Test parameters included porosity, thickness and clogging
percentage.
22
1.4 Structure of thesis
The thesis contains six chapters.
Chapter 1 gives an introduction on the use of pervious concrete in road
pavements. The research significance, objectives and scope of work are
highlighted.
Chapter 2 provides a review of the physical and mechanical
properties, the clogging and the sound absorption characteristics of pervious
concrete. Test methods for the various properties are also summarized.
Chapter 3 describes the test programme carried out on the physical
and mechanical properties of pervious concrete with and without steel fibers.
The materials, mix proportion, mixture preparation and test methods are
detailed. Test results are discussed and mixture proportions are recommended.
Chapter 4 presents the test programme and results on the clogging
characteristics of pervious concrete and porous asphalt with porosities ranging
from 10% to 25%. The effect of steel fiber inclusion on clogging is also
presented.
Chapter 5 discusses the test programme and results on the sound
characteristics of pervious concrete. Comparison with porous asphalt mixtures
is made.
Chapter 6 summarizes the work carried out and draws conclusions
and offers recommendations for future research.
23
CHAPTER 2 LITERATURE REVIEW
This chapter reviews previous works on the mechanical and physical
properties, clogging as well as sound absorption characteristics of pervious
concrete. The use of fibers in pervious concrete and test methods for clogging
are also described.
2.1 Physical and mechanical properties of pervious concrete
2.1.1 Effect of mixture proportion
The study on compressive strength, flexural strength, porosity and
permeability is of significance as they have been found to be influenced by the
mixture proportions, that is, cement content, coarse aggregate content and
water-cement ratio. When the cement content is increased, there will be an
increase in compressive and flexural strengths; however porosity and
permeability will be compromised. When the coarse aggregate content is
increased, the changes in compressive strength, flexural strength, porosity and
permeability are not as significant as other factors like the cement content and
water-cementitious ratio of the mixture proportion (ACI committee report 522,
2010).
The water-cementitious material (w/cm) ratio is an important
consideration to obtain the desired strength and void structure in pervious
concrete. A high w/cm ratio reduces the adhesion of the paste to aggregates
and causes the paste to flow and fill the voids even when lightly compacted. A
low w/cm ratio prevents good mixing and tends to cause balling in the mixer,
leading to an uneven distribution of cement paste, and therefore reducing the
ultimate strength and durability of concrete. Conventional w/cm ratio versus
24
compressive strength relation for normal concrete does not apply to pervious
concrete (ACI committee report 522, 2010).
Compared to conventional concretes with similar quantities of
cementitious materials, pervious concrete has lower compressive, flexural, and
bond strengths (Joung and Grasley, 2008; Crouch et al., 2007; Schaefer et al.,
2006; Fortes and Merighi, 2006; Kagata et al., 2004; Taniguchi and Yoshida,
2004; Zouaghi et al., 2000; Ghafoori et al., 1995; Malhorta, 1976).
The strength, porosity and permeability of pervious concrete depend on
the mixture design. Table 2.1 shows the typical ranges of material proportions
in pervious concrete according to the National Ready Mixed Concrete
Association (NRMCA, 2011) and the American Concrete Institute (ACI
Committee 522, 2010). Typical cement content is between 267 to 415 kg/m3,
coarse aggregate content ranges from 1190 to 1480 kg/m3 and water-cement
ratio from 0.27 to 0.36.
The strength and drainage properties of pervious concrete are primarily
determined by paste strength, aggregate type and volume of interconnected
voids (Crouch et al., 2007; Olek et al., 2003; Ghafoori et al., 1995 and Suzuki
et al., 1994).
Figures 2.1 to 2.3 show the effect of cement content, coarse aggregate
content and water-cement ratio, respectively, on the compressive strength,
flexural strength, porosity and permeability of pervious concrete.
Cement and coarse aggregate contents in the range of 200 – 500 kg/m3
and 1400 – 1800 kg/m3, respectively, resulted in compressive strength from 5 -
25
38 MPa; flexural strength from 0.5 - 4.8 MPa; porosity from 13 - 33% and
permeability from 1 - 32 mm/s. Increase in cement and coarse aggregate
contents typically results in an increase in the compressive and flexural
strengths, but a reduction in the permeability and porosity of pervious concrete
is not so distinct as indicated by Figures 2.1 and 2.2.
From Figure 2.3, it can be noted that a water-cement ratio ranging from
0.25 - 0.51 can result in compressive strength from 5 - 38 MPa; flexural
strength from 0.5 - 4.8 MPa; porosity from 2 - 33% and permeability from
0.25 - 31 mm/s. An increase in water-cement ratio resulted in a reduction in
compressive strength as well as permeability. The optimum water-cement ratio
ranges from 0.25 – 0.35 for a reasonable compressive strength, flexural
strength, porosity and permeability (Hesami et al.,2014; Bhutta et al., 2012;
Deo et al., 2011; Kevern et al., 2011; Huang et al., 2010; Neithalath et
al.,2010; Sumanasooriya et al., 2010 and Haselbach et al., 2006).
Figure 2.4 shows the effect of fiber dosage using polypropylene and
steel fibers. Fiber dosage ranging from 0.16% – 1%, results in compressive
strength from 7.5 – 22.5 MPa; flexural strength from 0.7 – 2.6 MPa; porosity
from 22 – 27.2% and permeability from 2.5 - 14 mm/s (Rehder et al., 2014;
Kevern et al., 2014; Hesami et al.,2014; Xiang et al., 2011 and Huang et al.,
2010).
2.1.1.1 Compressive strength
Research works by Sumanasooriya et al. (2012); Deo and Neithalath,
(2011); Neithalath et al. (2010); Sumanasooriya and Neithalath (2005) and
Bhutta et al. (2011) indicated that a reduction in the porosity of the pervious
26
concrete mixture would result in an increase in the compressive strength. This
result is supported by Agar-Ozbek et al. (2013) and Crouch et al. (2007) who
both noted that increasing the coarse aggregate content would result in a
decreasing amount of cement paste to fill up the pores and thus higher pore
contents in the pervious concrete matrix. As less cement paste is available for
aggregate bonding, the compressive strength would be lowered. Generally, a
10% increase in porosity approximately halves the compressive strength of
pervious concrete irrespective of the paste content and compaction procedure.
2.1.1.2 Flexural Strength
Nissoux et al. (1993) and Brite/Euram Report (1994) noted that a
flexural strength of about 3 MPa has been observed for a pervious concrete
proportioned using 6 to 10 mm aggregates and having 25% porosity. Bin
(2011) and Tennis et al. (2006) were both able to obtain flexural strength of
between 1.0 to 3.8 MPa.
2.1.1.3 Porosity
Porosity is highly dependent on several factors, that is, aggregate
gradation, cementitious material content, water-to-cementitious material ratio
and compactive effort (ACI Committee Report, 2010). Mulligan (2005) noted
that pervious concrete could achieve compressive strengths of approximately
17 MPa but with a reduction in porosity. This is supported by Schaefer et al.
(2008) who reported that the seven-day compressive strength decreased
linearly as porosity increased.
27
2.1.1.4 Permeability
The permeability of a material depends on the size and connectivity of
voids within its structure. It can be measured using the falling-head or the
constant-head permeameter method. In the falling head method, a fixed
amount of water is allowed to flow through the sample and the time taken for
all the water to flow through the sample is recorded. In the constant-head
permeameter method (Joung and Grasley, 2008; Delatte et al., 2007; Fortes
and Merighi, 2006; Olek et al., 2003), the sides of the pervious concrete
sample are sealed, a head (height) of water is maintained above the top end of
the sample and the volume of water that exits the lower end of the cylinder is
collected for a specified amount of time. The volume and the time taken are
measured, from which the permeability coefficient is determined.
Montes and Haselbach (2006) noted that the coefficient of
permeability of pervious concrete can range from 2 mm/s to 12 mm/s. It is
directly related to porosity and the pore sizes. Meininger (1988) has shown
that a minimum porosity of approximately 15% is required to achieve
significant permeability. For a porosity of 20% to 25% the coefficient of
permeability was reported to be approximately 10 mm/s (Brite/Euram Report,
1994).
2.1.2 Use of supplementary materials in pervious concrete mixes
Jing and Jiang (2003) reported that due to the presence of voids in
pervious concrete, it was difficult to obtain high strength by using common
material mix proportion. They found that the use of polymer superplasticer
and silica fume could enhance the strength of pervious concrete greatly. But it
28
was challenging to ensure good water permeability due to the polymer filling
up the pore spaces. They obtained a high compressive strength of about 50
MPa and a flexural strength 6 MPa but permeability was reduced to as low as
2.9 mm/s.
A study of pervious concrete incorporating lightweight aggregates was
performed by Kim and Lee (2010). They reported that samples with
lightweight aggregates had lower compressive strength compared to normal
weight aggregate samples.
Xiang et al. (2011) did a study on pervious concrete mixtures made
with latex and noted that these mixes exhibited lower porosity and
permeability but higher compressive and abrasion resistance than those
without latex. Results obtained from laboratory mixtures showed a low
permeability of 1.8 mm/s to 2 mm/s and compressive strength of 22 MPa to 30
MPa while field test mixtures gave a very low permeability of 0.2 mm/s but a
high compressive strength of 50 MPa.
Bhutta et al. (2011) evaluated high performance pervious concrete
(HPPC) properties using a thickening water-soluble cellulose based polymer
powder. The observed porosities were in the range of 18% - 23%, compressive
strength between 16 - 25 MPa, flexural strength between 3.5 – 4.8 MPa and
permeability between 2 –17 mm/s. They were able to obtain a high
compressive strength of 25 MPa and flexural strength of 4.8 MPa; however,
permeability was compromised and was around 2 mm/s.
It was concluded that the addition of polymer to pervious concrete
mixture would decrease the permeability but significantly increase the
29
compressive and flexural strengths. This is because of the strong bond
between the cement paste and aggregate resulting from the use of the polymer.
The use of recycled aggregates in pervious concrete was studied by
Sata et al. (2013). They reported that pervious concrete containing crushed
structural concrete materials and crushed clay brick gave lower compressive
strengths than those containing natural aggregates. A moderate compressive
strength of 13.6 MPa, low splitting tensile strength of 1.8 MPa but a high
permeability of 17.1 mm/s were recorded.
Last, the use of municipal solid waste incinerator bottom ash
(MSWIBA) in pervious concrete was investigated by Kuo et al. (2013). They
noted that there was no significant difference in compressive strength, porosity
and permeability between pervious concrete made with MSWIBA and those
made with natural aggregates. When MSWIBA was used in pervious concrete,
a low compressive strength but high permeability in the range of 4.8 – 12.7
MPa and 6 – 41 mm/s respectively were obtained.
From the above review, it can be noted that compressive strength and
flexural strength can be enhanced by using appropriate supplementary
materials but permeability and porosity would be compromised.
2.1.3 Fiber reinforcement for pervious concrete
Fibers can be made of synthetic and organic materials such as
polypropylene and cellulose; as well as steel. Joung (2008) noted that the use
of fibers has limited effect on the compressive strength of normal concrete but
a significant effect on the flexural strength of normal concrete. With sufficient
30
flexural strength and good permeability and porosity, fiber reinforced pervious
concrete can be used for pavements. Joung (2008) also concluded that
traditional straight fiber reinforcement such as polypropylene and cellulose
fibers will provide only minimal improvement in the flexural strength of
pervious concrete. Similarly, Kevern et al. (2014), Rehder et al. (2014), Xiang
et al. (2011), Schaefer and Kevern (2011) and Huang et al. (2010) found that
the use of polypropylene and cellulose fibers were unable to provide
satisfactory flexural strengths suitable for urban road usage.
Schaefer and Kevern (2011) noted that the addition of cellulose fibres
had limited effect on the initial workability of pervious concrete. Xiang et al.
(2011) tested pervious concrete with polypropylene fibers and obtained a
compressive strength of approximately 16 MPa and permeability of 3.4 mm/s,
which however do not satisfy the required performance for urban road usage.
Kevern et al. (2014) also studied polypropylene fibers at dosage rates of
0.16%, 0.33% and 0.49% per volume of concrete. They concluded that the
compressive and flexural strengths were also not significantly improved but
permeability decreased with the addition of cellulose fibers.
Hesami et al. (2014) did a study using steel fibers at a dosage rate of
0.5%. They reported a permeability ranging from 0.9 mm/s to 2.1 mm/s and a
flexural strength of about 2.7 MPa. They noted that the use of steel fibers
provided promising flexural strength and permeability.
In summary, polypropylene and cellulose fiber reinforced pervious
concrete did not give any strength enhancement, while steel fiber reinforced
31
pervious concrete appeared to be promising in meeting the target performance
for road use and need to be further studied.
2.2 Clogging characteristics of pervious concrete
The influx of stormwater containing suspended solid matter such as
dirt, fine sand and debris can lead to a gradual reduction in the drainage
capacity or permeability of pervious concrete when used as a surface course in
pavements or parking lots. The most common equipment used to study the
clogging characteristics of pavement material is the constant head or falling
head permeameter as mentioned in Section 2.1.1.4. Instead of using the
constant head permeameter to test for permeability, an adjustable wooden
flume machine to estimate the permeability of the specimen after clogging was
used by Haselbach et al. (2006).
The constant-head clogging method used in this study was referenced
from Tan et al. (2001), Mata, (2008), Joung et al. (2008) and Deo et al. (2009).
This clogging method was said to entail good repeatability of results. The
constant-head clogging test procedure involved the addition of clogging
material into the water which is then flushed through the specimen. The
permeability of the test specimen is measured after clogging and then
compared to a terminal permeability of 1 mm/s as recommended by Fwa et al.
(2002), Tan et al. (2000) and Fwa et al. (1998). If the terminal permeability is
not reached, the clogging cycles are continued until the permeability is smaller
than 1mm/s indicating that further addition of clogging material would cause a
negligible reduction in the permeability.
32
2.2.1 Effect of clogging materials
Runoff carrying with it a large amount of suspended particles is known
to be the main source that causes clogging of pore spaces in porous pavements
during their life time (Nielsen, 2007; Siriwardene et al. 2007 and Yong et al.
2008). Siriwardene et al. (2007) reported that clogging may also occur due to
the inorganic and organic particles from traffic activities and localized
vegetation or dust that is often found on roadways.
According to Cooley (1999), sand particles and solid materials are
pushed into the pores of the permeable pavement by the weight of the passing
vehicles which may also crush them into finer sizes. These sand and solid
particles can be brought into the pores by flowing water from a storm event. It
is possible that the vehicle weight may push materials into the pavement at the
front part of the tire, and the back part of the tire may create a suction to
remove some of the solids. Under certain conditions and depending on the
type and size of solids, once in the pores, the clogging materials may become
embedded and accumulate to cause clogging of the pores. When a significant
percentage of the pores in the permeable pavement are clogged, the
permeability of the pavement is reduced and water begins to pool on the
pavement surface. This will defeat the purpose of having a permeable
pavement.
Kayhanian et al. (2012) assessed the clogging of pervious pavements
in parking lots and reported that an important factor causing a reduction in
pavement permeability is the mass of fine particles less than 38 µm. The
presence of larger pore sizes due to large aggregates in the material resulted in
33
the easy entry of the clogging material through the pore structure, while
smaller pore sizes due to small aggregates inhibited the entry of the clogging
material into the pore structure. This was supported by works by Hasselbach et
al. (2006) and Taniguchi and Yoshida (2004) who reported that using smaller
aggregate sizes created smaller void spaces which was conducive to collecting
clogging material, which in turn gradually clogged the pores and rendered the
porous pavement impermeable.
Bean et al. (2007) investigated the influence of different clogging
materials such as sand sediments, fine grained sediments and a combination of
these materials on their deposition and subsequent reduction in the
permeability rates of pervious concrete pavements laid on either sandy soil,
silty soil or silty-sand soil. It was found that sand sediments were the most
detrimental clogging material. This finding was further supported by Deo et al.
(2010) who used fine sand of less than 0.84 mm in size and coarse sand
ranging from 0.84 mm to 1.80 mm in size to test for the permeability reduction
in pervious concretes due to clogging. When coarser sand was used as the
clogging material, the reduction in permeability was not substantial as the
coarse sand was larger than the pore size and thus unable to clog the pores of
the pervious concrete matrix.
Both Siriwardene et al. (2007) and Yong et al. (2008) concluded that
sand particles less than 6 μm in size was detrimental to pervious concrete.
Siriwardene et al. (2007) investigated the physical clogging of permeable
pavements and found that the main factor in the development of clogging was
the migration of particles less than 6 μm in diameter. Yong et al. (2008) also
used particles less than 6 μm present in the simulated stormwater to clog the
34
pavements. The accumulation of the particles less than 6 μm in diameter over
the 17.5 weeks resulted in significant clogging of the permeable pavement
when the flood storms were simulated.
In summary, from research done by Bean et al. (2007), Siriwardene et
al. (2007), Yong et al. (2008), Deo et al. (2010) and Kayhanian et al. (2012),
common sand sizes used in clogging tests are in the range of 6 μm to 1.80 mm.
2.2.2 Service life of pervious concrete pavements with clogging
A pervious concrete pavement upon opening to traffic may experience
an initial reduction in permeability as reported by Abbot and Comino-Mateos
(2006) who stated that clogging could occur within the first two years of
pavement construction and that pervious concrete pavement would experience
a reduction in permeability of up to 10% of its initial value in 2-3 years.
However, the pervious concrete pavement still retained its functionality in
years to come as Wingerter and Paine (1989) reported from a field
investigation conducted in Florida on pervious concrete pavements that
pervious concrete pavements showed small amounts of clogging after
approximately 13 years of service. Wanielista et al. (2007) also indicated that
pervious concrete pavement in Florida and other southeast United States
locations that were installed 10 to 15 years ago with no maintenance
requirements, were still operating in a satisfactory manner with insignificant
amounts of clogging.
35
2.3 Sound absorption properties of pervious concrete
Traffic noise reduction has become important especially to the
residential environment. To mitigate traffic noise, porous pavement materials
that can absorb sound waves over wide frequency ranges should be examined
(Mun, 2010).
An effective way to lower noise is to reduce noise generation at the
source. Pervious concrete is considered a quiet pavement (Rasmussen et al.
2008) as it produces noise level between 96 to 98 decibels dB(A) when tested
under normal traffic speed according to AASHTO TP76 Standard Method of
Test Measurement of Tire/Pavement Noise Using the On-Board Sound
Intensity (OBSI) Method (AASHTO 2010). For traditional concrete, the noise
level ranged from 100 to 110 dB(A) (National CP Tech Center, 2011).
When studying road noise due to vehicles travelling at normal traffic
speeds, most tires and road combinations show peaks within the range of 630 -
2000 Hz. This is particularly the case for car tires, but in many cases also for
truck tires (Sandberg, 2003). Most highway noise falls into a narrower
frequency range of 800 - 1200 Hz (Neithalath et al., 2005).
Wang and Lu (1999) and Voronina (1999) stated that in a rigid-framed
porous material, the pore walls are non-deforming, and thus acoustic
absorption occur primarily due to viscous losses and thermo-elastic damping
as the sound propagates through a large number of air cavities. Due to their
interconnected pores, pervious concrete and porous asphalt result in reduction
in tire-generated noise in two ways (Berhard, 2002). First, tire-pavement noise
generation is altered by a reduction in air pumping that occurs when air is
36
drawn into and pumped out of the gaps between tread blocks in the tires. This
allows air to escape through the pavement. Second, the reflection and
scattering of acoustic waves in the pores result in absorption and dissipation of
sound through internal friction (Neithalath et al., 2005).
In general, noise absorption characteristics are measured using the
impedance tube (Luong et al., 2014; Gonzalez et al., 2013; Izevbekhai, 2011;
Ahammed and Tighe, 2011; Kim and Lee, 2010; Seddeq, 2009; Park et
al.,2005; Tiwari et al., 2004 and Neithalath et al., 2005). For traffic noise, the
A-filter is used, which generally concentrates on the frequencies between 1000
and 4000 Hz; which are the frequencies for which human has the greatest
sensitivity as well as values in the 1/3 octave band. Values in which the A-
filter are used are referred to as “A-weighted decibels” or dB (A) (EUPAVE,
2015). Factors that affect the sound absorption capacity of a porous material
would be its porosity; tortuosity and thickness (Seddeq, 2009).
2.3.1 Acoustic properties of pervious concrete pavements
To measure sound pressure levels, a phonometer or the on-board sound
intensity method can be used. The phonometer is a device to measure the
sound intensity directly and this test method is different from the on-board
sound intensity (OBSI) test method which employs microphones attached to
the vehicle wheels.
From the sound level reading at a site test using a phonometer done by
Agostinacchio and Cuomo (2006), pervious concrete, normal concrete and
asphalt pavement each had a reading of 76.02 dB(A); 81.02 dB(A) and 79.90
dB(A) respectively. Based on sound absorption performance, pervious
37
concrete behaved better than conventional pavement materials such as normal
weight concrete and dense graded asphalt. When clogged, Izevbekhai (2011)
reported that the sound absorption capacity of pervious concrete pavements
was reduced.
For pervious concrete, the typical sound absorption coefficient (α)
ranges from 0.2 to 0.98 (Kim and Lee, 2010 and Park et al., (2005)), and from
0.1 to 0.90 for porous asphalt (Luong et al., 2014; Losa and Leandri, 2012;
Mun, 2010 and Meiarashi et al., 1995).
2.4 Target performances
Table 2.2 tabulates the target performances for pervious concrete.
Referring to AASHTO (1993) and FHWA (2011), a minimum flexural
strength of 3.5 MPa would be needed for pervious concrete pavement.
To be comparable to porous asphalt pavement in most countries in
Europe, USA and Asia, a minimum porosity of 20% is required for pervious
concrete (Belgian Road Research Center, 2000). As for the required
permeability, it is noted that for countries with temperate or drier climate,
permeability higher than 0.09 mm/s would be needed. However, due to South
East Asia’s tropical climate and the increasingly high intensity rainfall in
recent times, a permeability of more than 1.16 mm/s is necessary. Based on
the Brite/Euram Report (Brite-Euram Project, 1994) as well as to ensure
sufficient drainage in major pavements, a target permeability of more than 10
mm/s was therefore selected for this research.
38
Figures 2.5 and 2.6 show the target performance in terms of
compressive strength, flexural strength, porosity and permeability of pervious
concrete to be used in urban pavements, versus those of pervious concrete
investigated by various investigators. The latter include conventional as well
as fiber reinforced pervious concrete.
2.5 Summary
In this chapter, research works on pervious concrete, covering mixture
proportioning, compressive strength, flexural strength, porosity and
permeability, use of fiber reinforcement, clogging and sound absorption
characteristics were reviewed.
From the literature review on both pervious concrete and porous
asphalt mixes, satisfactory performance for pervious concrete for use in urban
pavements were set as having a flexural strength exceeding 3.5 MPa, porosity
more than 20% and permeability above 10 mm/s so as to ensure good
drainage.
For the study of clogging characteristics, common sand sizes used for
clogging tests range from less than 6 μm to 1.80 mm. The impedance tube
serves as the most appropriate sound absorption measurement method in the
laboratory and is widely used and adopted in this research. Porous pavement
materials provide higher sound absorption capacity over a wide frequency
range, thus aiding in tire/road noise reduction.
39
Table 2.1 Typical ranges of material proportions in pervious concrete
NRMCA
(2011)
ACI Committee 522
(2010)
Cementitious materials (kg /m3) 267 - 326 270 - 415
Aggregate (kg /m3) 1190 - 1480 1190 - 1480
w/cm (by mass) 0.27 – 0.36 0.27 – 0.34
Aggregate: cement ratio (by
mass) - 4 - 4.5
40
Table 2.2 Pervious concrete target requirements
Pervious
Concrete
Properties
Requirements Reference Remarks Target
Performance
Flexural
Strength
Normal Concrete
Pavement
3.5 MPa –
8.27 MPa
Normal Concrete
Pavement
AASHTO Guide
for design of
pavement
structures, 1993.
Specification
Pervious Concrete
Pavement
1.03 MPa
– 3.79
MPa.
0.60 MPa
– 4.80
MPa
Pervious Concrete
Pavement
FHWA, 2011,
Obla, 2007 and
Tennis et al.,
2004.
Various pervious
concrete
literature review:
Meininger 1988;
Xiang et al.,
2011; Huang et
al., 2010 and
Bhutta et al.,
2012.
General
property
Typical
laboratory
samples results
More than
3.5 MPa.
Porosity Pervious Concrete
Pavement
15 - 35%
13.0 -
32.6 %
Pervious Concrete
Pavement
ACI 522R-10
Report on
pervious
concrete
recommendation
Various pervious
concrete
literature review:
Meininger 1988;
Deo et al., 2011;
Neithalath et al.,
2010;
Sumanasooriya
et al., 2010;
Haselbach et al.,
2006; Huang et
al., 2010;
Kevern et al.,
2011 and Bhutta
et al., 2012.
General
property
Typical
laboratory
samples results
More than
20%.
41
Table 2.2 Pervious concrete target requirements (Cont’d)
Pervious
Concrete
Properties
Requirements Reference Remarks Target
Performance
Porosity
Asphalt porous
pavement
Europe
European
porous asphalt
mixes: at least
20% porosity.
United
Kingdom:
20% porosity
and 27.2 %.
Spain: 15 - 22
%.
Belgium: 19 –
25 %.
Switzerland:
14.6 - 21.1 %.
Netherlands:
minimum 20%
porosity.
Italy:
minimum 18 -
22 %.
Asphalt porous
pavement
Europe
Kandhal and
Mallick, 1998
Nicholls,
1998; Daines,
1986.
Ruiz et al.,
1990.
Van
Heystraeten
and Moraux,
1990.
Isenring et al.
1990.
Van der Zwan
et al., 1990.
Huber, 2000.
Specification
Specification
Specification
Specification
Specification
Specification
Specification
More than
20%.
Asia
Australia:
Porosity >
20% and 18 -
23 %.
Singapore: 20
- 26%.
Malaysia:
Porosity >
18%.
South Korea:
Porosity > 20
%.
South Africa:
5 - 6.5 %
Asia
Alderson, A,
1996, Leach
and Limb,
1986.
Land
Transport
Authority,
Guwe et al.,
2002.
JKR, 2008.
Hamzah et al.,
2004.
Liebenberg et
al., 2004.
Specification
Specification
Specification
Specification
Specification
42
Table 2.2 Pervious concrete target requirements (Cont’d)
Pervious
Concrete
Properties
Requirements Reference Remarks Target
Performance
Permeability
Pervious Concrete
Pavement
Singapore:
0.04 mm/s –
0.3 mm/s
1.35 mm/s –
12.2 mm/s
1.3 mm/s –
31 mm/s
10 mm/s for
a porosity of
20 – 25%
Pervious Concrete
Pavement
Chan et al.,
2012.
FHWA, 2011,
Obla, 2007 and
Tennis et al.,
2004.
Various
pervious
concrete
literature
review:
Meininger
1988;
Haselbach
et.al.,2006;
Mahboub et
al., 2009;
Xiang et al.,
2011; Huang
et al., 2010 and
Bhutta et al.,
2012.
Brite/Euram
Report , 1994.
Rainfall
intensity
General
Property
Typical
laboratory
samples
results
Typical
laboratory
samples
results
More than
10 mm/s.
.
Asphalt porous
pavement
USA
Georgia:
0.45 mm/s –
0.92 mm/s.
Arizona:
0.09 mm/s –
0.54 mm/s.
North
Carolina:
Permeability
> 1.16 mm/s.
Mississippi:
Permeability
> 0.35 mm/s.
Asphalt porous
pavement
USA
Santha, 1997.
Hossain et al.,
1992.
Putman and
Kline, 2012.
Putman and
Kline, 2012.
Specification
Specification
Specification
Specification
43
Table 2.2 Pervious concrete target requirements (Cont’d)
Pervious
Concrete
Properties
Requirements Reference Remarks Target
Performance
Permeability
Europe
European
porous
asphalt mix >
1.2 mm/s.
United
Kingdom:
5.43 mm/s –
7.79 mm/s
(laboratory
test); 11.3
mm/s to 50.9
mm/s (actual
road test).
Switzerland:
0.76 mm/s –
3.48 mm/s.
Europe
Watson et
al., 1998.
Daines,
1986.
Isenring et
al. 1990.
Specification
Laboratory
results and
actual road
tests
Specification
More than
10 mm/s. Asia
Singapore: 5–
8 mm/s.
Malaysia:
Permeability
> 1.16 mm/s.
South Korea:
Permeability
> 1 mm/s.
Asia
Guwe et
al., 2002.
Mallick,
2000 and
Hamzah et
al., 2010.
Hamzah et
al., 2004.
Typical
laboratory
samples
results
Specification
Specification
South Africa:
0.01 mm/s –
0.06 mm/s.
Liebenberg
et al., 2004.
Specification
44
Figure 2.1 Effect of cement content
45
Figure 2.2 Effect of coarse aggregate content
46
Figure 2.3 Effect of water-cement ratio
47
Figure 2.4 Effect of fiber dosage
48
Figure 2.5 Compressive strength (MPa) versus porosity (%)
Figure 2.6 Flexural strength (MPa) versus permeability (mm/s)
0
5
10
15
20
25
30
0 10 20 30 40
Com
pre
ssiv
e S
tren
gth
MP
a
Porosity %
Meininger (1988)
Huang et.al (2010)
Huang et.al (2010)
Polypropylene fibers
Deo et.al (2011)
Bhutta et al (2012)
Hesami et al (2014)
Target research area
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 5 10 15 20 25 30 35 40
Fle
xura
l S
tren
gth
MP
a
Permeability mm/s
Meininger (1988)
Huang et.al (2010)
Huang et.al (2010)
Polypropylene fibers
Xiang et.al (2011)
Xiang et.al (2011)
Polypropylene fibers
Bhutta et al (2012)
Hesami et al (2014)
Target research area
49
CHAPTER 3 PHYSICAL AND MECHANICAL PROPERTIES OF
PERVIOUS CONCRETE
An extensive test programme was carried out on the physical and
mechanical properties of pervious concrete. Part I of the test program covered
unreinforced pervious concrete with different mix proportions, while Part II
explored steel fiber reinforced pervious concrete. For Part I, the objective was
to achieve a mix design that provides adequate strength in pervious concrete
without compromising on porosity and permeability. The test variables studied
were coarse aggregate to cement ratio, w/c ratio, cement content and coarse
aggregate size. For Part II, the properties of pervious concrete reinforced with
discrete steel fibers were investigated. To satisfy traffic loading requirements
for major road pavements, the steel fiber-reinforced pervious concrete must
have adequate strength and be reasonably permeable to provide good drainage.
Hook-end steel fibers having different end configurations and in dosages from
1% to 2.5% by volume were considered.
3.1 Test programme
The mix proportions for pervious concrete in Part I of this
experimental study took into account existing practices as well as
recommendations from ACI Committee Report 522R-10. An earlier study by
Ang (2005) indicated that a coarse aggregate content of 1560 kg/m3 and water-
cement ratio of 0.3 resulted in a good permeability of 37.3 mm/s and porosity
of 25%.Therefore, the same aggregate content and water-cement were used as
the basis for the present study. Also, as a higher cement content would lower
both the permeability and porosity of pervious concrete, a moderate cement
50
content of 367 kg/m3 was selected. The increased coarse aggregate content of
1560 kg/m3 as compared to the recommended coarse aggregate range of 1190
– 1480 kg/m3 (ACI committee report 522, 2010) would also help to create
larger pores which are conducive in enhancing permeability and increasing
porosity.
Table 3.1 shows the type of tests conducted. They included tests for
compressive strength, flexural strength, porosity and permeability. For each
test three samples were used. The compressive strength test was carried out in
accordance with BS EN 12390-3: 2009 while the flexural strength test
followed ASTM C78-10. The porosity and permeability were determined
using methods employed in previous research works.
Table 3.2 shows the mix proportions of the samples. A total of 62
mixes were studied. Part I of the study consisted of Series R, A, B and C
specimens. Series R represents the reference mix with a w/c ratio of 0.3,
cement content at 367 kg/m3, coarse aggregate content at 1560 kg/m
3 and
water content at 110.1 kg/m3; Series A consisted of mixes with blended coarse
aggregates, that is, the CA/C ratio was kept at 6.45 and w/c ratio at 0.3 while
the ratios of small to large aggregates were varied and denoted by 0 : 1 (a), 1 :
3 (x), 1 : 1 (y), 3 : 1 (z) and 1 : 0 (b). In Series B, the water-cement ratio was
varied with other parameters kept the same as mix R. In Series C, the cement
content was varied.
Part II of the study consisted of the remaining three series, D, E and F,
specimens of which were cast with 3D-S, 4D and 5D discrete steel fibers (as
described in Section 3.1.1) respectively, with dosage varying from 1% to
2.5%. In these fiber-reinforced pervious concrete mixes, the w/c ratio, cement
51
content, coarse aggregate content and water were kept at 0.3, 367 kg/m3, 1560
kg/m3 and 110.1 kg/m
3 respectively.
3.1.1 Materials
ASTM Type I ordinary Portland cement with chemical composition
and physical properties complying with ASTM C 150-12 requirements was
used. Coarse aggregates were natural crushed granite complying with the
grading requirements of ASTM C 33-11a and having a specific gravity of
2.65. Table 3.3 shows the gradation of small and large size coarse aggregates.
The small coarse aggregates complied to Size 89 (9.5 to 1.18 mm) while the
large coarse aggregates complied to Size 67 (19.0 to 4.75 mm). A
conventional superplasticier meeting the requirements of ASTM C494 Type F
and G with a dosage of 1300 ml/ 100 kg of cement was used in Series A. The
conventional superplasticier belongs to the sulfonated naphthalene-
formaldehyde condensates polymer group. A comb polymer superplasticizer
(SP-C) formulated with carboxylated acrylic ester copolymers
(polycarboxylates), containing no added chloride and meeting the
requirements of ASTM C494 Type G superplasticier was used to improve
workability and in turn enhance the bonding between aggregates and cement
in all other series. The dosage of the superplasticier was 800 ml/ 100 kg of
cement.
Figure 3.1 shows the configurations and Table 3.4 tabulates the
properties of the steel fibers. The 3D steel fibers had 1 hook-end; while 4D
and 5D fibers had 1.5 and 2 hook-ends, respectively. The length and diameter
of the steel fibers range from 30 to 65 mm and 0.5 mm to 0.92 mm
52
respectively; the aspect ratio ranges from 60 to 80 and the tensile strength
from 1130 to 2250 MPa.
3.1.2 Test specimens
Figure 3.2 show the various types of test specimens. They were cast
and cured according to ASTM C192/C192M-15. Concrete cubes of 100 mm
side dimensions were used to study the compressive strengths; whilst prisms
measuring 100 mm by 100 mm in cross-section and 400 mm in length, were
used for the flexural tests. The cylindrical samples for porosity and
permeability tests had a diameter of 150 mm and a height of 50 mm. The
moulds were filled with freshly mixed concrete in three layers of
approximately equal volume. Each layer was tamped 25 times. After casting,
the samples were covered with a non-absorptive, non-reactive sheet of tough,
durable impervious plastic for 24 + 8 hours, after which they were demolded
9and cured in a fog room for 1, 7 or 28 days.
3.1.3 Test methodology
The Avery Denison test machine was used to obtain the compressive
and flexural strengths. The compressive strength test was determined
according to BS EN 12390-3: 2009 while the flexural strength test according
to ASTM C78-10.
The porosity of the hardened pervious concrete samples was
determined based on Archimedes principle by taking the difference in weight
between the oven-dry and water saturated submerged samples. It is given by
(Sonebi and Bassuoni, 2013; Bhutta et al., 2012, Lian et al, 2011; Goede, 2009
and Montes et al, 2005):
53
Vr = [ 1 − W2−W1
ρw V ] x 100% (3.1)
where: Vr = total void ratio in %; W1 = weight of sample immersed in water;
W2 = weight of sample in air; ρw = density of water and V = volume of
sample.
The above test method was initially proposed by Montes et al. (2005),
and was later incorporated into ASTM C1754/C1754M – 12; “Standard test
method for density and void content of hardened pervious concrete”.
The NUS constant head permeameter (Singapore Patent number
67286, 2001) was used to determine the permeability of the specimens. As
shown in Figure 3.3, a submersible pump provided a constant inflow of water
into the inlet cylinder such that a constant head of water was maintained at the
desired water head in the inlet cylinder. The flow of water was controlled
using valves. The flow rate of water was determined by measuring the volume
of water collected from the in-flow hose. The permeability samples were
sealed with waterproof thread tape to prevent side-flow of water, thus ensuring
1-D flow only. Plasticine was used to seal off any leakage that would occur in
the setup. During the test, the amount of outflow water was measured and the
permeability coefficient computed from the modified Darcy’s equation (Fwa
et al., 2002, Tan et al., 2000 and Fwa et al., 1998):
v = k . in (3.2)
in which
v = Q
t A (3.3)
i = H
L (3.4)
54
whereby k = permeability coefficient in mm/s; i = hydraulic gradient, n =
experimental coefficient; L = thickness of specimen in mm; Q = amount of
water collected in mm3; t = test duration in seconds; A = cross-sectional area
of the specimen and H = constant water head in mm. For the given test
materials and test conditions, n can be taken as a constant of 0.7 without any
significant error of practical significance (Fwa et al., 2002, Tan et al., 2000
and Fwa et al., 1998).
The ASTM C1688/C1688M – 12 method was used to determine the
density of fresh pervious concrete. The volume measure was first weighed and
recorded to the nearest gram. The freshly mixed pervious concrete was then
put into the container (Figure 3.4) and the cylinder was then weighed again to
the nearest gram. The density was calculated from:
D = (Mc – Mm)/Vm (3.5)
where: D = density (unit weight) of concrete, kg/m3; Mc = mass of the measure
filled with concrete, kg; Mm = mass of the measure, kg; Vm = volume of the
measure, m3.
3.1.4 Workability
Currently, there is no specification on the slump for pervious concrete.
To check for the workabiltiy of pervious concrete, the “Ball test”
recommended by Amde and Rogge (2013) and Goede (2009) was carried out.
The fresh pervious concrete for each mix gave good workability as shown in
Figure 3.5. The incorporation of steel fibers in the pervious concrete mix did
not cause any difference in workability of the fresh concrete. This can also be
55
observed from Figure 3.5. Both pictures (with and without steel fibers) show
good workability using the Ball Test.
The conventional slump test was also conducted as shown in Figure
3.6 to complement the “Ball test”. Zero or near zero slump was obtained for
all the test mixes. The use of steel fibers did not cause a change in the
workability and the slump was zero or near zero for both mixes with and
without steel fibers.
3.2 Test results and discussion
The test results for the physical and mechanical properties of all the
mixes at ages of 1, 7 and 28 days are listed in Table 3.5. The permeability test
results were only for the 28-day test. From the graphs of Series A to F shown
in Figure 3.7, there is an evident trend of compressive and flexural strengths
increasing and porosity decreasing over the period of 28 days. Pertaining to
the compressive strength trend, there was a significant increase in strength
from 1 to 7 days, while the compressive strength increase from 7 to 28 days
was not substantial. The increase in flexural strength was marginal while the
porosity values showed a consistent decline over the 28-days test period.
3.2.1 Unreinforced pervious concrete
Table 3.6 summarizes the 28-day test results for compressive strength,
flexural strength, permeability, porosity and density.
Effect of CA/C ratio. Specimens R1a and R1b both had a CA/C ratio of
4.25, within the ACI 522R-10 recommended range for pervious concrete. The
porosity was above 20%. The compressive and flexural strengths were
56
approximately 12.3 MPa and 2.7 MPa respectively. As shown in Figure 3.8(a),
Mix A1a and A1b with coarse aggregate-to-cement (CA/C) ratio of 6.45 had a
high porosity of about 30%. The large amount of coarse aggregates in the
specimens resulted in large pore gaps and thus higher porosities. However the
corresponding compressive strength was less than 10 MPa. As the pervious
concrete mixes are near zero slumps, mixes with smaller coarse aggregates
performed marginally better than mixes with larger coarse aggregates due to
the regular and more even arrangement of the aggregates in the concrete
matrix.
Mixes with a blend of coarse aggregates, that is, mix A1x, A1y, A1z
with small and large coarse aggregate in proportion of 1 : 3, 1 : 1 and 3 : 1
respectively, had lower permeability and porosity in comparison to mixes with
100% small coarse aggregates and 100% large coarse aggregates, as shown in
Figure 3.8(b).
The combined aggregate grading curves was plotted as shown in
Figure 3.8(c). The three blended gradations for mixes (A1x, A1y, A1z) fall
outside the upper and lower limits of ASTM C33 and thus these aggregate
gradations were not selected for further studies, and therefore only mixes with
(a) small coarse aggregates and (b) large coarse aggregates were examined in
the study.
Effect of w/c ratio. In Series B and as shown in Figure 3.9, the water-
cement ratio was varied from 0.2 to 0.35, although the recommended ACI
522R-10 range is between 0.27 to 0.34. With a water-cement ratio of 0.25, as
in Specimens B1a and B1b, the mix became too dry and brittle despite using a
57
higher dosage of the new range superplasticier (SP-C). As a result, a
comparatively low compressive strength of less than 15 MPa was obtained.
Permeability on the other hand increased to approximately 20 mm/s. The
permeability of the other Series B mixes was also reasonably high, i.e. more
than 20 mm/s, but the strengths were low, being 10 to 14 MPa in compression
and 2 to 3 MPa in flexure.
Effect of cement content. In Series C, the cement content was varied
from 242 kg/m3 to 495 kg/m
3, with water-cement ratio and coarse aggregate
content the same as Mixes R1a and R1b, that is, at 0.3 and 1560 kg/m3
respectively. Both the compressive and flexural strengths increased with
higher cement content regardless of whether small or large coarse aggregates
were used; however, the permeability reduced to as low as 4.25 mm/s as
shown in Figure 3.10. For practical use, the cement content should be around
400 kg/m3 to ensure a minimum flexural strength of 3 MPa and permeability
of more than 10 mm/s.
3.2.2 Steel fiber reinforced pervious concrete
Regardless of the use of small or large coarse aggregates in the mixes,
inclusion of steel fibers resulted in increasing compressive and flexural
strengths without compromising the permeability and porosity as shown in
Figures 3.11 to 3.14 for Series D, E and F mixes. No significant difference in
permeability, porosity, and compressive and flexural strengths were observed
58
between mixes reinforced with short or long 3D steel fibers, as shown in
Figure 3.15.
With increasing number of hooks at the ends of the steel fibers, the
flexural and compressive strengths were found to increase due to further
interlocking between the fibers and the cement paste, up to fiber dosage of
2.25%, as shown in Figures 3.11 and 3.12. However, the difference in flexural
strength were not significantly different among 3D, 4D and 5D steel fibers. A
minimum fiber dosage of 1.5% was needed to achieve the target flexural
strength of 3.5 MPa.
The use of 3D, 4D and 5D hook-end steel fibers showed some
differences in permeability and porosity, as shown in Figures 3.13 and 3.14.
The difference in permeability was more pronounced for the large coarse
aggregate mix as shown in Figure 3.13(b). This could be due to the irregular
settlement of the large coarse aggregates in the pervious concrete matrix
which thus led to a larger variation in permeability. With a higher fiber
content, improvement in permeability and porosity was not expected, due to
the balling effect and the uneven spread of fibers.
Figure 3.16 compares the observed flexural strength and permeability
of mixes with target performance indices. Regardless of the size of coarse
aggregates and fiber type, the permeability in general decreased with
increasing flexural strength. Mixes with smaller coarse aggregates and steel
fibers of multiple hook ends performed better than the others.
The target permeability is 10 mm/s and flexural strength is 3.5 MPa, as
recommended by AASHTO (1993) for road pavements. It is seen that mixes
satisfying the target performance were those using small coarse aggregates
59
with a fiber dosage of at least 1.5% for 3D fibers and 1% for 4D and 5D
fibers. For mixes using large coarse aggregates, the mixes meeting the targets
had between 1.5 and 2.25% of 3D fibers, or between 1 and 1.5% of 4D fibers.
Figure 3.17 shows the results for the compressive strength and
porosity. In general, the compressive strength decreased with increasing
porosity of the mix. The target porosity is 20% and compressive strength is 12
MPa. These were achieved in mixes with small coarse aggregates having 3D
or 4D fibers up to 2.25% or 5D fibers up to 2%. For mixes using large coarse
aggregates, the target compressive strength and porosity were achieved if the
fibre dosage is not more than 1.75%, 1.5% and 1%, respectively, for 3D, 4D
and 5D fibers.
From the above observations, the recommended fiber dosages to
ensure adequate flexural strength and reasonable permeability and porosity for
pavement use are summarized in Table 3.7. In general, a dosage of 1.5%
appeared to be the optimal. The most favourable mix (which has the best
combination of good porosity, permeability and flexural strength) would be
using small aggregates with 2% 5D steel fibers.
Figures 3.18 and 3.19 compare the current test results data with those
of other researchers. The flexural strength decreases with an increase in
porosity as well as permeability. Some of the current test results fall in the
upper right corner of the graphs and these results aid in the improvement of
pervious concrete mix design.
60
3.3 Summary
The first part of the test programme was carried out to investigate the
effect of mix proportion on the mechanical (compressive and flexural) and
physical (porosity and permeability) properties of pervious concrete. To
achieve a highly permeable and porous pavement with reasonable compressive
and flexural strengths, the CA/C ratio should be in the region of 4.25, water-
cement ratio of around 0.3 and cement in the range of 360 kg/m3 to 400 kg/m
3.
However, without the use of steel fibers, the target performances were not
achieved.
The second part of the test programme was conducted to investigate
the mechanical and physical properties of steel fiber-reinforced pervious
concrete for road pavement. It was noted that the steel fibers were effective in
increasing the compressive and flexural strengths of pervious concrete without
compromising on permeability and porosity. A minimum dosage of 1.5% steel
fiber by volume would be required to achieve the target flexural strength of
3.5 MPa, permeability of 10 mm/s and porosity of 20%.
The current study test results that fall in the upper right corner of the
graphs shown in Figure 3.18 and 3.19, aid in the improvement of pervious
concrete mix design done by past researchers: Hesami et al., (2014), Bhutta et
al., (2012), Xiang et al., (2011), Huang et al., (2010) and Meininger (1998).
61
Table 3.1 Types of tests and various test samples
Mechanical
and drainage
Properties
Destructive
test
Age at time
of testing of
concrete
(days)
No. of
specimen
for each
test
Test
method/standard/
references
Compressive
strength Yes 1,7 and 28 3 cubes
BS EN 12390-3:
2009
Flexural
strength Yes 7 and 28 3 prisms ASTM C78-10
Porosity No 1,7 and 28 3 cylinders
(Sonebi and
Bassuoni, 2013,
Bhutta et al.,
2012, Lian et al,
2011 and Goede,
2009)
Permeability No 28 3 cylinders
Modified Darcy’s
equation – (Fwa
et al., 2002, Tan
et al., 2000 and
Fwa et al., 1998)
62
Table 3.2(a) Mix proportion design (Part 1)
Mix Test
Variable
w/c
ratio
Cement
(C)/
[kg/m3]
Water/
[kg/m3]
Coarse
Aggregate
(CA)/
[kg/m3]
CA/C Additives
Part
I
Ra,b Reference
0.3
367 110.1
1560
4.25 SP-C
A1a,b,
x,y,z
CA/C
ratio 242 72.6 6.45
Conventional
SP
B1a,b
w/c ratio
0.2
367
73.4
4.25
SP-C
B2a,b 0.25 91.8
B3a,b 0.33 121.1
B4a,b 0.35 128.5
C1a,b
Cement
Content 0.3
242 72.6 6.45
C2a,b 300 90.0 5.20
C3a,b 400 120.0 3.90
C4a,b 430 129.0 3.63
C5a,b 495 148.5 3.15
* a: denotes small coarse aggregates (9.5mm); b: denotes large coarse aggregates
(19.5 mm) being used in the mix.
- x: denotes blended coarse aggregates with small and large coarse aggregates in
proportion of 1:3.
- y: denotes blended coarse aggregates with small and large coarse aggregates in
proportion of 1:1.
- z: denotes blended coarse aggregates with small and large coarse aggregates in
proportion of 3:1.
Table 3.2 (b) Mix proportion design (Part II)
Mix
Test
Variable
Steel fiber dosage by
volume of concrete (%)
Part
II
D1a,b
3D-S
Fibers
1.0
D2a,b 1.50
D3a,b 1.75
D4a,b 2.0
D5a,b 2.25
D6a,b 2.50
D7a 3D-L
Fibers 2.0
E1a,b
Steel 4D
Fibers
1.0
E2a,b 1.50
E3a,b 1.75
E4a,b 2.0
E5a,b 2.25
E6a,b 2.50
F1a,b
Steel 5D
Fibers
1.0
F2a,b 1.50
F3a,b 1.75
F4a,b 2.0
F5a,b 2.25
F6a,b 2.50
Note = All mixes in Part II had a w/c
ratio: 0.3, cement content: 367kg/m3,
water content: 110.1kg.m3, coarse
aggregate content: 1560 kg/m3, CA/C
ratio: 4.25 and used SP-C
superplasticier.
63
Table 3.3 (a) Gradation of small and large coarse aggregates
Size
(mm)
Large Coarse Aggregate
(% by mass)
Small Coarse Aggregate
(% by mass)
Cumulative
passing
Grading
requirement
Cumulative
passing
Grading
requirement
19.0 95 90 - 100 - -
12.5 - - - -
9.5 38 20 - 55 95 90 - 100
4.75 5 0 - 10 38 20 - 55
2.36 3 0 - 5 18 5 - 30
1.18 - - 5 0 - 10
0.30 - - 3 0 - 5
Pan 0 0 0 0
(b) Gradation of small and large aggregates in graphical form
Table 3.4 Properties of steel fibers
Steel Fibers
Type
Length
(mm)
Diameter
(mm)
Aspect
Ratio
Tensile Strength
(MPa)
3D-S 30 0.50 60 1130
3D-L 60 0.75 80 1100
4D 60 0.92 65 1500
5D 65 0.92 65 2250
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100
Per
cen
tage
Pass
ing (
%)
Sieve Size (mm)
Large Coarse AggregateLarge CA Lower limitLarge CA Upper limitSmall Coarse AggregateSmall CA Lower limitSmall CA Upper limit
64
Table 3.5: Physical and mechanical properties of pervious concrete
Test
Variable
Compressive Strength
MPa
Flexural Strength
MPa Porosity %
Permeability
mm/s
1-day 7-day 28-day 7-day 28-day 1-day 7-day 28-day 28-day
R1a Reference
4.22 10.3 11.9 1.85 2.68 27.0 24.3 22.1 13.8
R1b 5.12 10.7 12.6 2.78 2.75 26.9 24.2 21.6 13
Part
I
A1a
CA/C
ratio
4.24 5.20 8.4 NA NA 38.20 36.70 31.1 37.5
A1b 5.11 5.60 8.6 NA NA 42.10 40.40 35.5 39.8
A1x 4.22 6.10 8.9 NA NA 34.70 32.10 29.2 32.4
A1y 5.01 6.00 8.8 NA NA 35.30 33.60 30.8 34.7
A1z 4.25 6.20 9.1 NA NA 33.60 31.30 27.9 28.1
B1a
w/c ratio
4.22 9.7 11.6 1.41 1.98 32.2 25.8 23.0 23.5
B1b 5.01 10.4 11.7 1.53 1.86 28.0 25.1 22.2 17.1
B2a 4.25 10.3 11.8 2.11 2.54 29.2 25.8 22.6 22.4
B2b 5.08 11.2 12.0 2.09 2.78 27.7 25.1 21.8 14.0
B3a 4.40 10.1 13.1 2.29 2.82 25.6 20.5 18.3 12.1
B3b 5.25 11.0 14.2 2.69 2.88 21.9 19.7 17.4 11.0
B4a 4.62 11.2 13.9 2.69 2.90 20.0 17.7 15.5 11.2
B4b 5.36 11.8 14.3 2.48 2.93 18.8 17.0 14.8 9.7
C1a
Cement
content
2.60 6.0 8.4 1.12 1.58 43.5 34.8 31.1 35.9
C1b 3.01 6.4 8.6 1.39 1.69 44.7 40.1 35.5 37.8
C2a 3.01 7.4 9.7 2.10 2.53 32.3 28.5 25.0 20.8
C2b 3.61 8.0 10.3 2.00 2.66 39.1 35.4 30.8 26.3
C3a 6.42 14.9 20.7 2.57 3.02 18.3 14.7 13.1 7.7
C3b 8.12 17.2 23.2 3.03 3.11 17.8 15.9 14.1 9.5
C4a 8.96 22.0 28.9 3.01 3.23 16.6 14.7 12.9 6.2
C4b 12.53 27.9 35.8 2.80 3.25 9.4 8.5 7.4 4.0
C5a 11.04 25.6 35.6 3.18 3.58 11.8 9.4 8.4 4.8
C5b 14.63 30.9 39.8 3.34 3.52 6.6 5.9 5.2 3.7
Part II
D1a
3D-S Fibers
4.25 10.4 13.7 2.85 3.31 33.3 29.4 25.8 13.4
D1b 5.22 11.6 14.9 2.59 3.32 29.5 26.7 23.2 11.7
D2a 4.84 11.2 15.6 2.48 3.49 34.6 27.7 24.7 12.9
D2b 5.60 11.8 16.0 2.87 3.50 28.0 25.1 22.2 11.4
D3a 5.61 13.8 16.5 2.92 3.52 30.4 26.9 23.6 12.6
D3b 6.83 15.2 17.0 2.66 3.55 26.0 23.6 20.5 10.9
D4a 6.29 14.6 17.5 2.54 3.58 32.1 25.6 22.9 12.3
D4b 7.63 16.1 17.8 2.95 3.60 24.2 21.7 19.2 10.3
D5a 6.36 15.6 18.5 2.99 3.60 27.7 24.5 21.5 11.8
D5b 7.81 17.4 18.9 2.72 3.62 22.9 20.7 18.0 10.1
D6a 6.39 14.8 19.6 2.56 3.61 27.7 22.2 19.8 11.2
D6b 7.88 16.7 20.5 2.98 3.64 21.2 19.0 16.8 9.5
- N.A – results not available.
65
Table 3.5: Physical and mechanical properties of pervious concrete (cont’d)
Test Variable
Compressive Strength
MPa
Flexural
Strength MPa Porosity %
Permeability
mm/s
1-day 7-day 28-day 7-day 28-
day 1-day 7-day 28-day 28-day
Part
II
D7a 3D-L
Fibers 5.29 15.1 17.1 2.97 3.58 14.8 13.1 23.3 11.5
E1a
4D Fibers
4.24 11.8 15.1 2.62 3.33 30.1 27.3 23.7 13.1
E1b 4.19 11.0 15.3 2.49 3.34 29.3 23.4 20.9 10.8
E2a 4.45 12.4 16.7 2.91 3.55 29.0 26.0 23.0 12.3
E2b 4.97 13.1 17.2 2.95 3.55 25.9 22.9 20.1 10.5
E3a 5.48 15.2 17.3 2.73 3.64 28.2 25.5 22.2 12.0
E3b 5.72 15.0 17.8 2.56 3.60 27.0 21.6 19.3 9.4
E4a 5.70 15.8 18.4 3.08 3.76 27.3 24.5 21.7 11.2
E4b 6.41 16.9 18.8 3.05 3.68 24.0 21.2 18.6 8.9
E5a 6.12 17.0 19.3 2.87 3.83 24.1 21.9 19.0 10.9
E5b 6.27 16.5 20.1 2.63 3.71 23.9 19.2 17.1 8.3
E6a 5.94 16.5 20.5 3.21 3.91 22.1 19.8 17.5 10.8
E6b 6.79 17.9 21.1 3.17 3.82 20.4 18.0 15.8 7.2
F1a
5D Fibers
5.05 14.0 17.1 2.67 3.36 29.1 26.3 22.9 13.0
F1b 5.06 13.3 17.5 2.50 3.35 28.8 23.1 20.6 9.7
F2a 5.41 15.0 18.8 3.08 3.75 28.4 25.4 22.5 12.1
F2b 5.57 14.7 18.3 2.99 3.60 25.0 22.1 19.4 8.0
F3a 6.49 18.0 19.1 3.04 3.87 27.3 24.7 21.5 11.6
F3b 6.27 16.5 18.5 2.66 3.76 26.6 21.3 19.0 6.6
F4a 6.82 18.9 20.6 3.58 4.00 26.8 24.1 21.3 11.5
F4b 7.16 18.8 20.2 3.34 3.97 23.7 21.0 18.4 6.1
F5a 7.50 20.8 21.0 3.30 4.06 23.7 21.5 18.7 10.8
F5b 7.11 18.7 20.5 2.95 4.02 22.8 18.3 16.3 5.9
F6a 7.19 20.0 21.3 3.62 4.12 21.4 19.2 17.0 10.7
F6b 7.65 20.1 20.8 3.51 4.08 19.5 17.2 15.1 5.4
66
Table 3.6 Summary of test results
Mix Test
Variable
Compressive
Strength
[MPa]
Flexural
Strength
[MPa]
Permeability
[mm/s]
Porosity
[%]
Density
[kg/m3]
Part
I
R1a Reference
11.9 2.68 13.8 22.1 1890
R1b 12.6 2.75 13 21.6 2002
A1a
CA/C
ratio
8.4 N.A 37.5 31.1 N.A
A1b 8.6 N.A 39.8 35.5 N.A
A1x 8.9 N.A 32.4 29.2 N.A
A1y 8.8 N.A 34.7 30.8 N.A
A1z 9.1 N.A 28.1 27.9 N.A
B1a
w/c ratio
11.6 1.98 23.5 23.0 1710
B1b 11.7 1.86 17.1 22.2 1840
B2a 11.8 2.54 22.4 22.6 1814
B2b 12.0 2.78 14.0 21.8 1956
B3a 13.1 2.82 12.1 18.3 1923
B3b 14.2 2.88 11.0 17.4 2082
B4a 13.9 2.90 11.2 15.5 1978
B4b 14.3 2.93 9.7 14.8 2105
C1a
Cement
Content
8.4 1.58 35.9 31.1 1820
C1b 8.6 1.69 37.8 35.5 1900
C2a 9.7 2.53 20.8 25.0 1855
C2b 10.3 2.66 26.3 30.8 1943
C3a 15.7 3.02 7.7 13.1 2050
C3b 16.2 3.11 9.5 14.1 2040
C4a 20.9 3.23 6.2 12.9 2061
C4b 22.8 3.25 4.0 7.4 2080
C5a 35.6 3.58 4.8 8.4 2175
C5b 39.8 3.52 3.7 5.2 2196
Part
II
D1a
3D-S
Fibers
13.7 3.31 13.4 25.8 1825
D1b 14.9 3.32 11.7 23.2 1963
D2a 15.6 3.49 12.9 24.7 1830
D2b 16.0 3.50 11.4 22.2 1975
D3a 16.5 3.52 12.6 23.6 1855
D3b 17.0 3.55 10.9 20.5 1986
D4a 17.5 3.58 12.3 22.9 1872
D4b 17.8 3.60 10.3 19.2 1990
D5a 18.5 3.60 11.8 21.5 1923
D5b 18.9 3.62 10.1 18.0 2012
D6a 19.6 3.61 11.2 19.8 1951
D6b 20.5 3.64 9.5 16.8 2094
D7a 3D-L
Fibers 17.1 3.58 11.5 23.3 1892
E1a
4D Fibers
15.1 3.33 13.1 23.7 1831
E1b 15.3 3.34 10.8 20.9 1963
E2a 16.7 3.55 12.3 23 1846
E2b 17.2 3.55 10.5 20.1 1991
E3a 17.3 3.64 12.0 22.2 1875
E3b 17.8 3.60 9.4 19.3 2009
E4a 18.4 3.76 11.2 21.7 1905
E4b 18.8 3.68 8.9 18.6 2015
E5a 19.3 3.83 10.9 19.0 1933
E5b 20.1 3.71 8.3 17.1 2027
E6a 20.5 3.91 10.8 17.5 1965
E6b 21.1 3.82 7.2 15.8 2056
67
Table 3.6 Summary of test results (Cont’d)
Mix Test
Variable
Compressive
Strength
[MPa]
Flexural
Strength
[MPa]
Permeability
[mm/s]
Porosity
[%]
Density
[kg/m3]
Part
II
F1a
5D Fibers
17.1 3.36 13.0 22.9 1840
F1b 17.5 3.35 9.7 20.6 1979
F2a 18.8 3.75 12.1 22.5 1854
F2b 18.3 3.60 8.0 19.4 2030
F3a 19.1 3.87 11.6 21.5 1863
F3b 18.5 3.76 6.6 19.0 2051
F4a 20.6 4.00 11.5 21.3 1931
F4b 20.2 3.97 6.1 18.4 2086
F5a 21.0 4.06 10.8 18.7 1986
F5b 20.5 4.02 5.9 16.3 2097
F6a 21.3 4.12 10.7 17.0 2012
F6b 20.8 4.08 5.4 15.1 2103
Table 3.7 Recommended steel fiber dosages
Maximum size of
coarse aggregates
(mm)
3D Fibers 4D Fibers 5D Fibers
9.5 1.5 – 2.25% 1 – 2.25% 1 – 2 %
19.0 1.5 – 1.75% 1 – 1.5% Nil
68
Figure 3.1 Steel 3D-S, 3D-L, 4D and 5D hook-end fibers (Dramix)
(a) Compressive test specimen (b) Permeability test specimen
(c) Flexural test specimen
Figure 3.2 Test samples
5D Fiber (2 hook-end)
3D-S Fiber (1 hook-end)
3D-L Fiber (1 hook-end)
4D Fiber (1.5 hook-end)
69
Figure.3.3 Constant-head permeability test set-up
Figure 3.4 Volume measure with fresh pervious concrete for density test
70
(a) Too little water (b) Appropiate amount of water (c) Too much water
Without steel fiber With steel fiber
(d) Current study
Figure 3.5 Ball test for workability of pervious concrete (Sonebi and Bassuoni,
2013)
(a) Without steel fiber (b) With steel fiber
Figure 3.6 Slump test
71
(a) Series A – blend ratio
(b) Series B – w/c ratio
Figure 3.7: Physical and mechanical properties of pervious concrete
0
5
10
15
20
25
30
35
1-day 7-day 28-day 1-day 7-day 28-day 28-day
Compressive Strength (MPa) Porosity (%) Permeability
(mm/s)
A1a A1b A1x A1y A1z
0
5
10
15
20
25
30
35
1-day 7-day 28-day 7-day 28-day 1-day 7-day 28-day 28-day
Compressive Strength (MPa) Flexural Strength (MPa) Porosity (%) Permeability
(mm/s)
B1a B1b B2a B2b R1a R1b B3a B3b B4a B4b
72
(c) Series C – cement content
(d) Series D – 3D-S fibers
Figure 3.7: Physical and mechanical properties of pervious concrete (cont’d)
0
5
10
15
20
25
30
35
40
45
50
1-day 7-day 28-day 7-day 28-day 1-day 7-day 28-day 28-day
Compressive Strength (MPa) Flexural Strength (MPa) Porosity (%) Permeability
(mm/s)
C1a C1b C2a C2b R1a R1b C3a C3b C4a C4b C5a C5b
0
5
10
15
20
25
30
35
40
1-day 7-day 28-day 7-day 28-day 1-day 7-day 28-day 28-day
Compressive Strength (MPa) Flexural Strength (MPa) Porosity (%) Permeability
(mm/s)
D1a D1b D2a D2b D3a D3b D4a D4b D5a D5b D6a D6b D7a
73
(e) Series E – 4D fibers
(f) Series F – 5D fibers
Figure 3.7: Physical and mechanical properties of pervious concrete (cont’d)
0
5
10
15
20
25
30
35
1-day 7-day 28-day 7-day 28-day 1-day 7-day 28-day 28-day
Compressive Strength (MPa) Flexural Strength (MPa) Porosity (%) Permeability
(mm/s)
E1a E1b E2a E2b E3a E3b E4a E4b E5a E5b E6a E6b
0
5
10
15
20
25
30
35
1-day 7-day 28-day 7-day 28-day 1-day 7-day 28-day 28-day
Compressive Strength (MPa) Flexural Strength (MPa) Porosity (%) Permeability
(mm/s)
F1a F1b F2a F2b F3a F3b F4a F4b F5a F5b F6a F6b
74
* R: denotes the reference mix, a: denotes small coarse aggregates (9.5mm);
b: denotes large coarse aggregates (19.5 mm) being used in the mix.
(a) Effect of size
(b) Effect of blend ratio
0
10
20
30
40
50
60
R1a A1a R1b A1b
Pro
per
ties
Mix
Compressive Strength [MPa] Flexural Strength [MPa]
Permeability [mm/s] Porosity [%]
xx xx
0
10
20
30
40
50
60
A1a A1x A1y A1z A1b
Pro
per
ties
0 : 1 1 : 3 1 : 1 3 : 1
Compressive Strength [MPa]
Permeability [mm/s]
Porosity [%]
1 : 0
Small to
large
aggregate
ratio
75
(c)
Figure 3.8 Effect of coarse aggregate size in unreinforced pervious concrete
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100
Per
cen
tage
Pass
ing (
%)
Sieve Size (mm)
Large CA Lower limit
Large CA Upper limit
Small CA Lower limit
Small CA Upper limit
A1x 1:3
A1y 1:1
A1z 3:1
76
(a) Mixes with small coarse aggregates
(b) Mixes with large coarse aggregates
Figure 3.9 Effect of water-cement ratio in unreinforced pervious concrete
0
5
10
15
20
25
30
0.2 0.25 0.3 0.33 0.35
Pro
per
ties
w/c ratio
Compressive Strength (MPa) Flexural Strength (MPa)
Permeability (mm/s) Porosity (%)
0
5
10
15
20
25
30
0.2 0.25 0.3 0.33 0.35
Pro
per
ties
w/c ratio
Compressive Strength (MPa) Flexural Strength (MPa)
Permeability (mm/s) Porosity (%)
77
(a) Mixes with small coarse aggregates
(b) Mixes with large coarse aggregates
Figure 3.10 Effect of cement content in unreinforced pervious concrete
0
10
20
30
40
50
60
242 300 367 400 430 495
Pro
per
ties
Cement Content (kg/m3)
Compressive Strength (MPa) Flexural Strength (MPa)Permeability (mm/s) Porosity (%)
0
10
20
30
40
50
60
242 300 367 400 430 495
Pro
per
ties
Cement Content (kg/m3)
Compressive Strength (MPa) Flexural Strength (MPa)Permeability (mm/s) Porosity (%)
78
(a) Small coarse aggregates
(b) Large coarse aggregates
Figure 3.11 Compressive strength of fiber reinforced pervious concrete
10
12
14
16
18
20
22
24
1 1.5 1.75 2 2.25 2.5
Com
pre
ssiv
e S
tren
gth
(M
Pa)
Volume fraction of steel fiber (%)
5D
4D
3D-S
10
12
14
16
18
20
22
24
1.0 1.5 1.8 2.0 2.3 2.5
Com
pre
ssiv
e S
tren
gth
(M
Pa)
Volume fraction of steel fiber (%)
5D
4D
3D-S
79
(a) Small coarse aggregates
(b) Large coarse aggregates
Figure 3.12 Flexural strength results of fiber reinforced pervious concrete
0
1
2
3
4
5
1 1.5 1.75 2 2.25 2.5
Fle
xura
l S
tren
gth
(M
Pa)
Volume fraction of steel fibers (%)
5D
4D
3D-S
0
1
2
3
4
5
1.0 1.5 1.8 2.0 2.3 2.5
Fle
xura
l S
tren
gth
(M
Pa)
Volume fraction of steel fibers (%)
5D
4D
3D-S
80
(a) Using small coarse aggregates
(b) Using large coarse aggregates
Figure 3.13 Permeability results of fiber reinforced pervious concrete
0
2
4
6
8
10
12
14
1.0 1.5 1.8 2.0 2.3 2.5
Per
mea
bil
ity (
mm
/s)
Volume fraction of steel fibers (%)
3D-S
4D
5D
0
2
4
6
8
10
12
14
1.0 1.5 1.8 2.0 2.3 2.5
Per
mea
bil
ity (
mm
/s)
Volume fraction of steel fibers (%)
3D-S
4D
5D
81
(a) Using small coarse aggregates
(b) Using large coarse aggregates
Figure 3.14 Porosity results of fiber reinforced pervious concrete
10
12
14
16
18
20
22
24
26
28
1.0 1.5 1.8 2.0 2.3 2.5
Poro
sity
(%
)
Volume fraction of steel fibers (%)
3D-S
4D
5D
10
12
14
16
18
20
22
24
26
28
1.0 1.5 1.8 2.0 2.3 2.5
Poro
sity
(%
)
Volume fraction of steel fibers (%)
3D-S
4D
5D
82
Figure 3.15 Effect of fiber length in fiber reinforced pervious concrete
0
5
10
15
20
25
30
Compressive
Strength (MPa)
Flexural Strength
(MPa)
Porosity (%) Permeability
(mm/s)
3D short 3D Long
83
Figure 3.16 Flexural strength versus permeability of test mixes
Figure 3.17 Compressive strength versus porosity of test mixes
84
Figure 3.18 Relationship between flexural strength and porosity of pervious
concrete
Figure 3.19 Relationship between flexural strength and permeability of
pervious concrete
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 10 20 30 40
Fle
xura
l S
tren
gth
MP
a
Porosity %
Meininger (1988)
Huang et.al (2010)
Huang et.al (2010)
Polypropylene fibers
Bhutta et al (2012)
Hesami et al (2014)
Lim et al. (2013a,b)
Present study-Steel
fibers mix
AASHTO
Recommendation
Target research area
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 5 10 15 20 25 30 35 40
Fle
xura
l S
tren
gth
MP
a
Permeability mm/s
Meininger (1988)
Huang et.al (2010)
Huang et.al (2010)
Polypropylene fibersXiang et.al (2011)
Xiang et.al (2011)
Polypropylene fibersBhutta et al (2012)
Hesami et al (2014)
Lim et al. (2013a,b)
Present study-Steel
fibers mix
AASHTO
Recommendation
Target research area
85
CHAPTER 4 CLOGGING CHARACTERISTICS OF PERVIOUS
CONCRETE
The clogging resistance of pervious concrete pavement governs its
functional durability and its service life. In this study, the clogging
characteristics of pervious concrete was investigated using four types of sand
with sizes ranging from less than 75 µm to 1.18 mm, which are most
commonly found on Singapore’s roads. The critical sand size was adopted to
further compare the clogging characteristics of pervious concrete with porous
asphalt.
4.1 Evaluation of clogging characteristics and porosity
While it is important to design a porous pavement with a high level of
porosity and permeability, it is equally important to ensure that the pores are
not easily clogged up so that a sufficiently high level of permeability could be
maintained throughout the service life of the pavement. Thus it is important to
evaluate the initial permeability of a porous pavement material as well as the
reduction in permeability caused by clogging.
In practice, porous asphalt and pervious concrete may be considered.
The laboratory study was therefore carried out to compare the permeability
and clogging characteristics of a pervious concrete mixture with a porous
asphalt mixture with various mixture porosities. The test program considered
four target porosity levels, 10%, 15%, 20% and 25%, which cover the
practical range of porosity. Permeability coefficient (i.e. hydraulic
conductivity) was selected as the drainage parameter to characterize the
drainage capacity of porous materials. The permeability coefficient was
86
determined by a constant head permeameter, and the clogging performance
was determined using a constant-head permeameter. The clogging
characteristics was studied by introducing clogging materials into the porous
materials and measuring the decrease in permeability coefficient of the test
materials at different stages of clogging.
4.1.1 Measurement of permeability coefficient
A constant-head test apparatus was used to measure the coefficient of
permeability as described in Chapter 3 and shown schematically in Figure 3.3.
An upstream inflow reservoir was used to maintain a constant upper water
level, while a downstream outflow weir was used to establish a constant lower
water level. The apparatus consisted of an open-ended vertical cylinder with
an internal diameter of 150 mm to receive a 150 mm diameter specimen. A
submersible pump provides a constant inflow of water into the inlet cylinder.
In the present study, a constant hydraulic head of 41.5 cm was maintained
throughout the test.
4.1.2 Clogging procedure
To establish the clogging permeability deterioration trend, clogging
materials were introduced in ten cycles so that a sufficient number of data
points could be obtained before the test specimen was fully clogged. A series
of trial clogging tests were conducted to determine an appropriate amount of
clogging material to apply at each cycle, and it was found that applying 5.3 g
(i.e. an application amount of 2000 g per square m) per cycle would allow 10
clogging cycles to be conducted before the specimen was rendered fully
clogged and reached terminal clogging state. The adopted clogging procedure
87
is described as follows: 5.3 gram of clogging material in the form of fine-
grained soil was brought into each specimen by means of water that was
repeatedly fed through the 150 mm diameter cylinder of the constant head
permeameter. Permeability coefficient measurements were performed
repeatedly at an interval of three minutes until the change in the measured
permeability value was negligible. To establish the deterioration in
permeability as clogging developed, the permeability of the specimen was
measured after each and every of the ten cycles of the clogging process.
To find out the amount of soil retained in the specimen, the specimen was
weighed before and after each clogging stage. The entire test procedure,
including the clogging process and permeability coefficient measurements,
took 3 to 3.5 hours per specimen.
4.1.3 Clogging materials
The soils deposited from dirty wheels of vehicles, or vehicles carrying
earth or construction materials have been the major sources of clogging
materials on porous pavements. For this study, sand was used as a clogging
material because it is commonly found on urban roads. Residual soil was also
used as it is the common subgrade soil that pavements in Singapore are
constructed upon and spillage of this material has been known to clog the
pores of porous asphalt pavements. Their sizes usually range from less than 75
μm to 1.18 mm. Figure 4.1 shows the gradations of typical residual soils and
construction sands commonly found on Singapore roads and used as clogging
materials in this study. Earlier studies by Fwa et al. (2002), Tan et al. (2000)
and Fwa et al. (1998), found that of the various sizes of these clogging
88
materials, fines smaller than 75 µm had insignificant effect in inducing
clogging as compared to the larger size materials, and that the component with
sizes between 600 µm and 1.18 mm were the most detrimental in creating
clogging in porous materials. Hence, this component of the residual soil was
employed in the clogging procedure in the present study.
4.1.4 Measurement of porosity
The pervious concrete porosity test was determined from equation
(3.1) given in Chapter 3. The porosity test method was initially originally
proposed by Montes et al. (2005), and later incorporated into ASTM
C1754/C1754M – 12: standard test method for density and void content of
hardened pervious concrete.
The asphalt porosity test follows ASTM: D1188 – 07, whereby the
asphalt specimens were wrapped with parafilm and the porosity of the asphalt
specimens determined as follows:
% air void = D− Sm
D x 100 (4.1)
with
D = Wagg+WbitWagg
2.63+
Wbit1.05
(4.2)
Wbit = WA
100−WA x Wagg (4.3)
Sm = A𝑎𝑖𝑟
A𝑎𝑖𝑟−B (g/ml) (4.4)
89
whereby Aair = mass of dry specimen in air, g; B = mass of specimen
immersed in water, g; Wbit = Weight of bitumen, g; Wagg = Weight of
aggregate, g.
4.2 Pavement mixtures
The first part of this research was to study how pervious concrete and
porous asphalt mixtures differ in their permeability and clogging
characteristics. For each of the two mixture types, four sets were prepared to
achieve approximately the following levels of porosity: 10%, 15%, 20% and
25%. The second part was to examine how steel fiber pervious concrete
mixtures with varying fiber dosages perform. The fiber dosage studied were:
1%, 1.5%, 2% and 2.5%.
4.2.1 Pervious Concrete Mixtures
Details of the pervious concrete and steel fibers can be found in
Section 3.2.1. To produce specimens of the target porosity levels as well as
with different steel fiber dosages, specimens were prepared using different
mix proportions as shown in Table 4.1. The water-cement ratio was held
constant at 0.3 and the coarse aggregate content at 1560 kg/m3. Triplicate
samples were produced for each mix design. The mixtures with the “F” in its
designation contained steel fibers.
4.2.2 Porous Asphalt Mixtures
The asphalt mixtures were the porous asphalt mixtures used in
Singapore road construction. Table 4.2 shows the aggregate gradations and
90
mix proportions of three open-graded/porous asphalt paving mix designs for
pavement wearing course: mix PA-13 with porosity (i.e. air void content)
ranging from 8 to 12% approximately, mix PA-16 having porosity from 15%
to 20% approximately, and PA-20 with porosity from around 20% to more
than 25%. Crushed granite stone aggregate, which was the common type of
road making aggregate in Singapore, was used for the mixes. The asphalt
binder was a polymer modified binder of grade PG76-22. The porosity of each
mix could be varied by adjusting the binder content within the allowable range
of 4.5 to 5.5% by weight of total mix.
4.3 Test results and discussion
4.3.1 Effect of different clogging materials
Four types of clogging materials were used to determine the most
detrimental sand size for pervious concrete as well as porous asphalt. A porous
mix (PC20) of 20% porosity was chosen as reference, as this is commonly
adopted in construction.
Figure 4.2 shows the deterioration in permeability of pervious concrete
and porous asphalt over ten cycles of clogging with four different types of
clogging materials. In general, clogging increased with the size of the clogging
material. Medium to coarse sand (600 μm to 1.18 mm) was most detrimental
in causing clogging. This is because this type of sand consists of a large
proportion of relatively large size sand particles, which are less likely to pass
through the pore structure thus causing a blockage.
The amount of residual soil that adhered to pervious concrete was
insignificant. The residual soil was observed to pass through the specimen
91
almost immediately after being added into the inlet cylinder of the constant
head permeameter. Residual soil (less than 75 μm) is therefore least
detrimental in clogging pervious concrete.
4.3.2 Comparison of permeability
Table 4.3 presents the initial porosity and permeability coefficient of
both pervious concrete and porous asphalt specimens. Figure 4.3 shows that
for both pervious concrete and porous asphalt mixtures, the initial
permeability coefficient increases exponentially with the porosity level, as
represented by the following two regression equations:
for pervious concrete: k = 0.949e0.132P
R2 = 0.922 (4.5)
for porous asphalt: k = 0.627e0.126P
R2 = 0.898 (4.6)
where k = permeability coefficient in mm/s, and P = porosity in percent. It is
therefore beneficial to raise the initial porosity as much as practical, without
compromising on the strength of the material.
Table 4.4 shows that the permeability coefficient, k and rate of
permeability, ∆k/ ∆P, increase with porosity. Pervious concrete had a higher
permeability coefficient than porous asphalt with the same porosity; the
difference being larger with higher porosity. The difference in permeability
coefficient increased from 1.3 mm/s at a porosity of 10% to 11.1 mm/s at a
porosity of 25%. The rate of increase of permeability coefficient with porosity
was thus higher for pervious concrete than for porous asphalt. Thus higher
gains in permeability coefficient from increasing mix porosity can be achieved
in pervious concrete compared to porous asphalt.
92
4.3.3 Comparison of clogging behaviour
As described earlier, clogging material was added in ten equal amounts of
5.3g each so that the changes in permeability could be monitored as clogging
developed. Therefore, including the initial permeability value, there were
eleven data points of permeability measurements that defined the permeability
deterioration trend caused by clogging.
Figure 4.4 shows the clogging test results of the pervious concrete and
porous asphalt mixes. For each of the four permeability deterioration curves
(corresponding to four porosity levels), the range of measured permeability
values at each of the ten stages of the clogging process is also indicated. The
variation of the measured permeability coefficient values obtained from three
replicate test specimens is represented by the range bars indicated in Figure
4.4. Pervious concrete always performed better than porous asphalt with the
same initial porosity at each stage of clogging development.
Excluding the pervious concrete with 20% porosity, the higher the porosity
level, the higher was the variation among the measured permeability
coefficient data. This could be because a mixture with a higher porosity would
have more flow channels, and there would be more possible patterns of
clogging development than a mixture with a lower porosity, thus leading to
larger variations in the resulting permeability coefficient values in the
clogging tests of replicate specimens.
The deterioration in permeability of both porous materials can be described
by exponential relation obtained from regression analysis:
93
For pervious concrete with:
10% Porosity: k = 2.453e-0.338N
R2 = 0.996 (4.7)
15% Porosity: k = 13.019e-0.271N
R2 = 0.948 (4.8)
20% Porosity: k = 15.790e-0.304N
R2 = 0.989 (4.9)
25% Porosity: k = 17.117e-0.062N
R2 = 0.952 (4.10)
For porous asphalt with:
10% Porosity: k = 2.127e-0.291N
R2 = 0.992 (4.11)
15% Porosity: k = 4.927e-0.416N
R2 = 0.978 (4.12)
20% Porosity: k = 7.668e-0.290N
R2 = 0.992 (4.13)
25% Porosity: k = 15.272e-0.211N
R2 = 0.992 (4.14)
where k = permeability coefficient in mm/s, and N = number of clogging
cycle. The residuals for equations (4.7) to (4.14) were normally distributed as
the P-value was more than 0.05 using the Anderson-Darling Normality Test as
shown in Annex A.
For porous asphalt mixtures, Figure 4.4(b) shows that the relative
permeability of specimens of the four target porosity levels remained
unchanged throughout the clogging process. Generally, differences in
permeability coefficients of different target porosity levels decreased as the
clogging process progressed. This is also the case for the test results of
pervious concrete specimens shown in Figure 4.4(a).
94
The permeability deterioration curves in Figure 4.4 suggest that, for both
pervious concrete and porous asphalt, there was a significant improvement in
permeability performance when the mixture porosity was increased from 20%
to 25%.
The permeability deterioration curves of pervious concrete and porous
asphalt are compared in Figure 4.5. The difference between the two material
types was smallest (in the order of about 2 mm/s) for a porosity of 10%, and
largest (approximately of the order of 5 mm/s) for a porosity of 25%.
Clogging was reached when the deterioration in permeability began to
level off and there was negligible change in the permeability coefficient
between successive clogging stages. As shown in Figure 4.5, except for
pervious concrete and porous asphalt specimens with an initial porosity of
25%, all specimens with lower initial porosity reached the terminal state
before the 10th
stage of clogging. This finding further reinforces the need to
design for a porosity of more than 20% for porous pavement mixes in practice.
Hypothesis testing using the T-test: Two-samples assuming unequal
variances statistical analysis was conducted for the permeability deterioration
of the eight porous mixtures, namely: PC10, PC15, PC20, P25, PA10, PA15,
PA20 and PA25, for clogging cycles 0 to 10. The result are shown in Annex B
Table B-1. Based on the analysis, most of the results were accepted at the 95%
confidence level as most of their p-values were less than 0.05. The null
hypothesis was rejected in favor of the alternative hypothesis. For values
highlighted in bold, their p-value was greater than 0.05, therefore the results
were not statistically significant at the 95% significance level. The null
hypothesis was not rejected and the results were not statistically different.
95
Figure 4.6 shows the appearance of the pervious concrete and porous
asphalt specimens after clogging tests. Test results suggested that pervious
concrete was superior to the porous asphalt in resistance to clogging. Based on
past studies (Shimeno et al., 2010; Fwa et al., 2002, Tan et al., 2000 and Fwa
et al., 1998 and FCPA, 1990), the factors that affect the clogging behaviors of
a porous material include (i) type of clogging materials, (ii) gradation of
aggregates in the mixture, and (iii) the type of binder. Factor (i) was ruled out
in this study because the same type of clogging material was used for the
clogging tests. As for factor (ii), the use of large size aggregates is known to
improve permeability and clogging resistance, but is unlikely to be a main
reason in the present study even though the coarse aggregate gradation of
pervious concrete varied from those of the porous asphalt mixtures. The most
likely reason was probably due to the properties of the binders used and
Manning roughness coefficient. The Manning roughness coefficient is based
on the empirical Manning formula, estimating the average velocity of a liquid
flowing in a conduit that does not completely enclose the liquid. The Manning
coefficient is dependent on many factors including surface roughness and
sinuosity (FHWA, 2005). Serving as walls for flow channels in the porous
mixture, asphalt and concrete would exhibit different flow resistance. Their
clogging resistance would be affected by their adhesion properties with
clogging materials. In this instance, the Manning roughness coefficients for
asphalt and concrete would be different, thereby contributing to different
resistance to flows.
So far no other research has been done to evaluate how the properties of
the binders affect the clogging behaviour. However it was noted that when
96
exposed to higher temperature, the asphalt becomes more viscous and more
fine particles are attracted to it. Further research is needed to study in detail
the effects of these factors on the different clogging-resistance characteristics
of the two porous materials.
4.3.4 Effect of steel fibers on clogging behaviour
Figure 4.7 shows the appearance of pervious concrete with steel fibers
after they were subjected to clogging tests. The steel fiber dosage is given in
Table 4.1 and the measured porosity of the specimens in Table 4.5. The steel
fiber reinforced pervious concrete had a water-cement ratio of 0.3, cement
content of 367 kg/m3, water content of 110.1 kg/m
3, coarse aggregate content
of 1560 kg/m3 and steel fiber dosage varying from 1% to 2.5%, in the mixture
proportion.
The reduction in coefficient of permeability in steel fiber reinforced
pervious concrete due to the introduction of clogging materials is shown in
Figure 4.8. All mixes have porosity of around 20% (see Table 4.5), that is,
ranging from 23% with 1% fiber, to 17% with 2.5% fiber. The initial
permeability coefficient was around 13 mm/s for Mix F1 (with 1% fiber)
decreasing to 11 mm/s for Mix F2.5 (with 2.5% fiber), compared to about 15
mm/s for the pervious concrete mix PC20/F0 without steel fibers. For
comparison, the results for a porous asphalt mix PA20 with a porosity of 20%
and initial permeability of about 9 mm/s is also shown in Figure 4.8.
The reduction in permeability coefficient was similar for mixes
containing fibers up to about 2%. With higher steel fiber dosage, the reduction
was higher especially in the initial few cycles. The permeability coefficient of
97
previous concrete was higher than that of porous asphalt at all stages,
especially where the steel fiber content was less than 2%, indicating that it is
less susceptible to clogging. After ten cycles of clogging, however, the
permeability coefficient of all samples reduced to below 1 mm/s.
4.4 Evaluation of clogging potential of porous materials
The Kozeny-Carmen equation (Tan et al., 2003) has been used widely
in the modelling of the clogging mechanisms of various media. The equation
is given by:
k0 = (λ ρw g/ηw)[np3/(1- np)
2] (1/ sv
2) (4.15)
where,
k0 : initial permeability of permeable medium (m/s),
λ : shape factor function of tortuosity of medium,
ρw : density of water (kg/m3),
g : acceleration due to gravity (m/s2),
ηw : viscosity of water (kg/m.s),
np : porosity of permeable medium,
sv : volumetric specific surface area of permeable medium
= 6/dp for spherical particles (m-1
)
= 4/df for fibers (m-1
),
dp : mean particle diameter (m), and
df : fiber diameter (m).
The effect of clogging can be considered by introducing a term known
as the specific deposit of the clogging material, σ which is given by
σ = Vc / VT (4.16)
in which
98
Vc = mc / ρc (4.17)
where
VT : volume of specimen (m3),
Vc : clogging material retained within the specimen (m3),
mc : mass of clogging material retained in specimen (kg), and
ρc : density of clogging material (kg/m3).
Based on Kozeny-Carmen equation, Giroud (1996) derived a
theoretical model for the reduction in the permeability of geotextiles due to
soil clogging. Blazejeski and Sadzide (1997) used the Kozeny-Carmen
equation to study the effect of permeability on sand due to clogging. Later on,
Wu and Huang (2000) also modified the Kozeny-Carmen equation to study
the effects of sediment clogging gravel beds.
Tan et al. (2003) earlier formulated a theoretical model to study the
clogging behavior of permeable bases. According to the model, the reduced
permeability caused by clogging can be expressed as a function the initial
permeability k0 as follows:
k = 𝑘0 (1−𝑛)2
𝑛3
(𝑛− ∝𝑐𝜎)3
[1−(𝑛−∝𝑐𝜎)]2 (4.18)
where,
k : permeability of specimen (mm/s),
k0 : initial permeability of specimen (mm/s),
np : porosity of specimen,
σ : specific deposit of clogging material, and
αc : empirical constant.
99
The empirical constant αc is a positive value which is related to the rate
of deterioration of permeability caused by clogging. A higher αc would
indicate a more rapid decrease in permeability for the porous material tested.
In the current study, the experimental empirical constant αc was
determined from Equation (4.18) for pervious concrete and porous asphalt.
4.4.1 Analysis of permeability reduction due to clogging
Figure 4.9 shows the average amount of soil retained with respect to
permeability from three samples for pervious concrete and porous asphalt after
clogging tests.
By rearranging equation (4.18), a non-linear system with c on both
sides of the equation is formed and shown in equation (4.19). By performing
iterative substitution, the c values can be obtained. Figure 4.10 depict the c
factor of the pervious concrete and porous asphalt specimens with target
porosities at 10%, 15%, 20% and 25%.
𝑘
𝑘0
𝑛3
(1−𝑛)2 [1 − (𝑛 −∝𝑐 𝜎)]2 = (𝑛 −∝𝑐 𝜎)3 (4.19)
The properties of pervious concrete mixtures that affect the value of αc
include the initial porosity, the gradation of aggregates and the cement
content; whilst the properties of porous asphalt mixtures that affect the values
of αc are the initial porosity, the gradation of aggregates and the type and
grade of asphalt binder.
100
Figure 4.11 illustrates that pervious concrete had lower permeability
deterioration factor c compared to porous asphalt at all porosity levels. This
implies that pervious concrete has better clogging resistance performance as
compared to porous asphalt.
Figure 4.12 shows pervious concrete reinforced with 2% steel had
comparable permeability deterioration factor c as unreinforced pervious
concrete with an initial porosity of 20%. This indicates that the incorporation
of fibers did not affect the clogging resistance of pervious concrete.
It is of interest to note that when the initial porosity is less than 10% or
more than 24%, the deterioration c factor would be lower. At low porosity, it
is difficult for the clogging materials to find their way into the test specimen,
resulting in a low deterioration rate of permeability. As the initial porosity
increases, more clogging materials could be brought into and trapped within
the specimen to result in clogging, and hence a higher rate of permeability
deterioration. However when the initial porosity of the specimen becomes
sufficiently high, the flow channels in the specimen are wide and the flow
velocity is high enough to carry the clogging materials through the specimen
without causing much clogging.
4.5 Summary
The results of a laboratory clogging study have been reported and
analysed in this chapter. The study compared the permeability and clogging
characteristics of two types of porous pavement materials at four levels of
porosity: 10%, 15%, 20% and 25%. The two porous materials studied were
101
pervious concrete and porous asphalt. Three replicate specimens were
prepared at each target porosity level for each of the two test materials. In the
clogging test of each test specimen, a laboratory clogging procedure was
adopted to introduce a fixed amount of clogging material in ten stages by
means of a constant-head apparatus. This procedure allowed permeability
coefficient to be measured at each stage and thus enabled deterioration in
permeability to be determined as clogging progressed.
For both pervious concrete and porous asphalt mixtures, the
permeability and clogging resistance increased substantially when the mixture
porosity was increased beyond 20%. These findings provide supporting
experimental evidence to the common practice of specifying a porosity of
more than 20% for porous pavement materials. Also, at all four porosity
levels, the pervious concrete specimens gave higher initial permeability than
the porous asphalt specimens. The difference became larger as the porosity
increased.
Comparing the deterioration in permeability of pervious concrete with
porous asphalt specimens, it was found that for the same porosity, pervious
concrete always performed better than porous asphalt throughout the entire
clogging process. Again, the difference between the performances of the two
material types increased with porosity.
Incorporation of steel fibers dosage up to 2% did not affect the
clogging resistance of pervious concrete. The current study is of significance
as a comparison of the permeability and clogging characteristics of pervious
102
concrete and porous asphalt at four levels of porosity: 10%, 15%, 20% and
25% was made.
103
Table 4.1 Mixture design of pervious concrete
Mix w/c
ratio
Cement/
[kg/m3]
Water/
[kg/m3]
Coarse
Aggregate/
[kg/m3]
Target
porosity level
[%]
Steel Fiber
dosage
[%]
PC10
0.3
495 148.5
1560
10
- PC15 400 120.0 15
PC20* 367 110.1 20
PC25 300 90.0 25
F1
367 110.1 20
1.0
F1.5 1.5
F2 2.0
F2.5 2.5
* Reference mix
104
Table 4.2 Aggregate gradations and mix composition of porous asphalt mix
designs
Mix Design Porous Asphalt
PA-13
Porous Asphalt
PA-16
Porous Asphalt
PA-20
Sieve Size (% passing) (% passing) (% passing)
20mm - - 100
16mm - 100 95
13.2mm 100 70 85
9.5mm 85 59 72
4.75mm 45 33 22
2.36mm 30 22 18
1.18mm 25 16 -
600um 20 10 13
300um 13 6 9
150um 10 4 7
75um 4 3 6
Asphalt Binder
Content (% by
Weight of
Total Mix)
4.5 to 5.5
Air void
content (%) 8 to 12 15 to 20 20 to 25 or
more
105
Table 4.3 Porosity and permeability coefficient of pervious concrete and
porous asphalt specimens
Target
Porosity
Porous Asphalt Pervious Concrete
Actual
Specimen
Porosity (%)
Permeability
Coefficient
(mm/s)
Actual Specimen
Porosity (%)
Permeability
Coefficient
(mm/s)
10%
8.82 2.68 9.95 4.70
11.4 2.49 7.30 1.94
10.8 2.26 7.24 1.58
15%
14.0 3.19 16.2 8.79
16.2 3.60 16.2 11.4
16.4 3.45 15.5 9.81
20%
18.5 9.72 21.6 14.6
18.6 8.79 20.7 15.2
21.6 8.64 19.3 14.6
25%
24.6 13.5 24.1 26.2
23.8 11.5 26.3 23.4
26.6 21.1 26.7 25.3
106
Table 4.4 Rates of increase of permeability coefficient with porosity for
porous asphalt and pervious concrete mixtures
Porosity
(%)
Permeability
coefficient, k (mm/s)
∆k/ ∆P
Difference
between k
of Porous
Asphalt
and
Pervious
Concrete
(mm/s)
Porous
Asphalt
Pervious
concrete
Porous
Asphalt
Pervious
concrete
10 2.2 3.6 0.40 0.66 1.3
15 4.2 6.9 0.72 1.28 2.7
20 7.8 13.3 1.36 2.48 5.5
25 14.6 25.7 - - 11.1
107
Table 4.5 Measured porosity of steel fiber pervious concrete specimens
Target
Porosity Mix
5D Steel Fiber
Dosages (%)
Initial
Porosity
(%)
Average Porosity (%)
20%
F1 1
23.9
22.9 23.4
21.4
F1.5 1.5
23.5
22.5 24.1
19.9
F2 2
22.4
21.3 20.5
21.0
F2.5 2.5
18.0
17.2 17.0
17.2
108
Figure 4.1 Gradations of common clogging materials on Singapore roads
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10
Per
cent
Pas
sing (
%)
Particle Size (mm)
Medium-coarse sand
Fine-medium sand
Fine to coarse sand
Residual Soil
109
(a) Pervious Concrete
(b) Porous Asphalt
Figure 4.2 Permeability versus clogging stages of pervious concrete and
porous asphalt at 20% porosity.
0
2
4
6
8
10
12
14
16
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity,
k (
mm
/s)
Clogging Cycle
Residual Soil (Less than 75µm)
Fine to medium sand (150µm to 600µm)
Fine to coarse sand (75µm to 1.18mm)
Medium to coarse sand (600µm to 1.18mm)
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity,
k (
mm
/s)
Clogging Cycle
Residual Soil (Less than 75µm)Fine to medium sand (150µm to 600µm)Fine to coarse sand (75µm to 1.18mm)Medium to coarse sand (600µm to 1.18mm)
110
Figure 4.3 Relationship between porosity and permeability coefficient
Pervious concrete:
y = 0.949e0.132P
R² = 0.922
Porous asphalt:
y = 0.627e0.126P
R² = 0.898
02468
1012141618202224262830
0 5 10 15 20 25 30
Per
mea
bil
ity c
oef
fici
ent,
k (
mm
/s)
Porosity, P (%)
Pervious Concrete
Porous Asphalt
111
(a) Pervious Concrete with Target Porosity P%.
(b) Porous Asphalt with Target Porosity P%.
Figure 4.4 Effect of clogging cycle on permeability coefficients
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity C
oef
fici
ent,
k (
mm
/s)
Clogging Cycle
PC 10% PC 15%
PC 20% PC 25%
0
2
4
6
8
10
12
14
16
18
20
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity C
oef
fici
ent,
k (
mm
/s)
Clogging Cycle
PA 10% PA 15%PA 20% PA 25%
112
Figure 4.5 Comparison of permeability deterioration curves of porous asphalt
and pervious concrete mixtures
0123456789
101112131415161718192021222324252627
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity C
oef
fici
ent,
k (
mm
/s)
Clogging Cycle
PA 10% PA 15%PA 20% PA 25%PC 10% PC 15%PC 20% PC 25%
Legend:
PA = Porous Asphalt
PC = Pervious Concrete
Numerical values indicate porosity %
PC 25%
PC 20%
PA 25%
PC 15%
PA 20% PA 15%
PC 10%
PA 10%
113
(i) 10% (ii) 15%
(iii) 20% (iv) 25%
(a) Pervious Concrete
(i) 10% (ii) 15%
(iii) 20% (iv) 25%
(b) Porous Asphalt
Figure 4.6 Pervious concrete and porous asphalt mixes of different porosities
after clogging effect
114
Figure 4.7 Clogged fiber reinforced pervious concrete specimen
Figure 4.8 Clogging characteristics of steel fiber reinforced pervious concrete
specimens
0123456789
10111213141516
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity C
oef
fici
ent,
k (
mm
/s)
Clogging Stage
PC20 F1 F1.5
F2 F2.5 PA20
PC20/F0
F2
F1.5
F1
F2.5
PA20
115
(a) Pervious concrete
(b) Porous Asphalt
Figure 4.9 Average soil retained for pervious concrete and porous asphalt
samples with different porosities
0
2
4
6
8
10
12
14
16
18
20
22
0 500 1000 1500 2000
Per
mea
bil
ity,
k (
mm
/s)
Soil retained (g/m2)
10% 15% 20% 25%
0
2
4
6
8
10
12
14
16
18
0 500 1000 1500 2000
Per
mea
bil
ity,
k (
mm
/s)
Soil retained (g/m2)
10% 15% 20% 25%
116
(a) Pervious concrete
(b) Porous Asphalt
Figure 4.10 Permeability deterioration factor (αc)
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity d
eter
iora
tion f
acto
r, α
c
Clogging cycle
PC10 PC15 PC20 PC25
0
2
4
6
8
10
12
14
16
18
20
22
24
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity d
eter
iora
tion f
acto
r, α
c
Clogging cycle
PA10 PA15 PA20 PA25
117
(a) 10% porosity
(b) 15% porosity
Figure 4.11 Permeability deterioration factor (αc) for pervious concrete and
porous asphalt specimens
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity d
eter
iora
tion f
acto
r, α
c
Clogging cycle
PC10 PA10
0
1
2
3
4
5
6
7
8
9
10
11
12
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity d
eter
iora
tion f
acto
r, α
c
Clogging cycle
PC15 PA15
118
(c) 20% porosity
(d) 25% porosity
Figure 4.11 Permeability deterioration factor (αc) for pervious concrete and
porous asphalt specimens (Cont’d)
0
2
4
6
8
10
12
14
16
18
20
22
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity d
eter
iora
tion f
acto
r, α
c
Clogging cycle
PC20 PA20
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity d
eter
iora
tion f
acto
r, α
c
Clogging cycle
PC25 PA25
119
Figure 4.12 Permeability deterioration factor (αc) for unreinforced pervious
concrete and fiber reinforced pervious concrete specimens
0
1
2
3
4
5
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity d
eter
iora
tion f
acto
r, α
c
Clogging cycle
F2 PC20
120
CHAPTER 5 SOUND ABSORPTION CAPACITY OF PERVIOUS
CONCRETE
Due to the rapid rate of urbanisation throughout the world, road traffic
noise has become a significant public concern as over exposure to noise over
an extended period of time can cause serious health problems such as sleeping
disturbance, hypertension, immunity decline and psychological imbalance.
There are two ways to mitigate road traffic noise: (i) to reduce the volume of
traffic on the roads, (ii) to install sound absorption barriers and (iii) to reduce
tire-pavement noise through selection of pavement wearing course materials.
In this study, the focus is on method (iii) by increasing the sound
absorption capacity of the road pavement. This is a measure that targets the
problem of road traffic noise emission at the source. Pervious concrete
pavement has the capacity to absorb and dissipate sound in view of the voids
in the matrix of its porous structure. However a durability issue to note is that
over time, clogging of the pores in the pervious concrete pavement will reduce
its capacity for sound absorption. Therefore, it is of interests to study the
following issues in evaluating the sound absorption capacity of pervious
concrete:
1. The sound absorption performance of pervious concrete compared to
other common road materials such as normal weight concrete, dense
graded asphalt and porous asphalt mixtures;
2. The effect of the initial porosity of the pavement in relation to the
sound absorption capacity of pervious concrete;
121
3. The effect of the thickness of the pavement on the sound absorption
capacity of pervious concrete; and
4. The effect of clogging on the sound absorption capacity of pervious
concrete.
5.1 Experimental Program
Table 5.1 shows the experimental program for the present study. A
total of 32 mixes grouped into four series “A” to “D” were studied. Series “A”
consisted of specimens with different road materials; Series “B” comprised
pervious concrete and porous asphalt mixes with different porosities; Series
“C” consisted of mixes with different sample thickness and Series “D”
considered specimens subjected to different degrees of clogging. The “degree
of clogging” (% clogged) is defined as percentage of original porosity
retained, that is, % clogged = ( Pclogged / Poriginal ) x 100%.
5.1.1 Pavement materials
Table 5.2 shows the coarse and fine aggregate gradations for pervious
concrete, normal weight concrete and lean concrete. Lean concrete is a
concrete with high water content and low cement content. It is usually used as
the sub-base in pavement construction. For the pervious concrete and normal
weight concrete mixtures, the cement, coarse aggregates and 5D hooked-end
steel fibers were the same as those specified in Section 3.1.1.
The fine aggregates used for the normal weight concrete and lean
concrete mixes were natural sand complying with the requirements of ASTM
C 33-11a and having specific gravity of 2.60. Table 5.3 details all the concrete
122
mix proportions used in this sound absorption study. The 28-day compressive
strength for the normal weight concrete mixture and lean concrete mixture
were 40.1 MPa and 7.8 MPa respectively.
The asphalt mixtures were those used in Singapore road construction.
Table 5.4 shows the aggregate gradations and mix proportions of one dense
graded asphalt mix (W3B) and three open-graded/porous asphalt paving mix
designs (PA-13, PA-16 and PA-20) for pavement wearing course. W3B has
porosity ranging from 3% to 4%, mix PA-13 has porosity ranging from 8% to
12% approximately, mix PA-16 has porosity from 15% to 20% approximately,
and mix PA-20 has porosity from around 20% to more than 25%. Crushed
granite stone aggregate, which was the common type of road making
aggregate in Singapore, was used for the mixes. The asphalt binder was a
polymer modified binder of grade PG76-22. The porosity of each mix could
be varied by adjusting the binder content within the allowable range of each
mix design. Three replicate specimens for each kind of mix (same porosity
and thickness) were compacted and analyzed. The results of the three replicate
tests samples were then averaged to give the results presented in this study.
The bituminous mixtures had been compacted in samples of approximately 6.3
cm in height using a Marshall compactor.
5.1.2 Test specimens and conditioning
The samples in Series A, B and C had a diameter of 100 mm, while
those in Series D had a diameter of 150 mm. The samples in Series A, B and
D were 50 mm thick. For Series C, the test variable is the effect of thickness of
sample layer, therefore three sample thicknesses were explored: 63 mm, 100
123
mm and 200 mm. Figure 5.1 shows schematically the 100 mm diameter and
150 diameter moulds used to hold the specimens during testing. The holes in
the plates are to ensure that the sample mould/holder could be secured tightly
to the impedance tube by screws.
Medium to coarse sand (600 um to 1.18 mm) in size was used as
clogging material in Series D specimens. The clogging procedure was the
same as that described in Chapter 4. The clogged specimens of five different
degrees of clogging can be seen from Figure 5.2 and 5.3.
5.1.3. Acoustic absorption measurement
The acoustic absorption coefficient of a test specimen was measured
using a Bruel & Kjaer (B&K) impedance tube for a frequency range from 100
to 2000 Hz following the BS EN ISO 10534-2 (2001) specification.
Figure 5.4 show the sound absorption test setup with low and high
frequency impedance tubes. Measurements were carried out according to the
standing wave method in which a loudspeaker sets up a sound field in a tube
which was terminated by the sample at the far end. A pure tone signal is
supplied to the loudspeaker and a plane wave is generated in the tube in the
direction of the sample. The wave is partially reflected from the sample and
the interference between the incident and reflected waves gives rise to a
standing wave pattern. By measuring the ratio between the maximum and
minimum sound pressure, the absorption coefficient of the sample for zero
degree incident sound can be calculated. Since the sample was the only
absorbing material, the measured absorption coefficient α is very closely
related to its sound absorbing properties.
124
By means of a clamping device, the sample holder was fastened to one
end of the measuring tube; the other end of which was screwed onto the box
containing the loudspeaker. The probe microphone was supported by a small
gliding carriage. Through an axial hole in the loud speaker, the probe
microphone was then inserted into it.
The sample was laterally coated with a thin film of silicone to eliminate
the air gap between the specimens and the tube. This is because if the sample
is not well insulated inside the impedance tube, the absorption measurements
could be affected by the air that escaped from an open pore on the sides of the
specimen.
Frequencies of 100 Hz to 500 Hz are considered to be in the low frequency
range while 600 Hz to 2000 Hz to be in the high frequency range. For the low
frequencies; 100, 150, 200, 250, 300, 350, 400 and 500 Hz, the impedance
tube was 100 mm in diameter and 1 metre in length. For the high frequencies;
600, 700, 800, 900, 1000, 1250, 1500, 1750 and 2000 Hz, the impedance tube
was 29 mm in diameter and 0.28 metre in length. The averages of three
readings were taken for each frequency.
Figure 5.5 illustrates why the diameter of the impedance tube has to be
smaller for higher frequencies so as to be able to sustain a standing wave in
the tube (Allard, 1993). Take for instance at 1000 Hz, the wavelength is 3 cm
for which the pressure would not be uniform across a diameter of 100 mm.
Therefore to maintain a plane wave across the diameter of the tube, a smaller
diameter of 29 mm is needed. At 2000 Hz, the wavelength is about 1.5 cm for
which the pressure would not be uniform across a diameter of 100 mm.
125
Therefore to maintain a plane wave across the diameter of the tube, a smaller
diameter of 29 mm is still needed.
The frequency range of interest was limited to 100 Hz to 2000 Hz in
this study. A 100 Hz threshold was used as the lowest limit because at lower
frequencies, the acoustic pressure was hard to stabilize. The higher limit of
2000 Hz was used because tire-pavement noise is most prevalent to the human
ear at frequencies of 800 – 1200 Hz. In the case of a material that absorbs
sound waves perfectly, the absorption coefficient, α, would be 1.0, whereas a
material that does not absorb sound at all would have an absorption
coefficient, α, equal to 0 (Neithalath et al., 2006).
5.2 Test results and discussion
5.2.1 Effect of different road materials (Test Series A)
The measured sound absorption coefficient for Test Series A (see
Table 5.1), covering eight road materials, namely: pervious concrete (PC);
steel fiber-reinforced pervious concrete (PF); normal weight concrete (NC),
steel fiber-reinforced normal weight concrete (NF), lean concrete (LC), porous
asphalt (PA), open-graded asphalt (OG) and dense asphalt (NA), are
summarised in Table 5.5 and plotted in Figure 5.6. The following can be
deduced from the test results:
Effect of steel fibers. The sound absorption capacities of both pervious
concrete and normal weight concrete, with and without fibers, did not differ
significantly for the entire frequency range. It thus can be said that the use of
steel fibers do not affect the sound absorption properties of the mixes.
126
Pervious concrete versus normal concrete. Pervious concrete had
better sound absorption capacity compared to normal weight concrete for the
entire frequency range. Notably, the maximum value of sound absorption
coefficients, α, for pervious concrete and normal weight concrete were 0.92
and 0.12 respectively. The lowest sound absorption coefficients for pervious
concrete and normal weight concrete were 0.40 and 0.07 respectively.
Normal weight concrete versus lean concrete. The sound absorption
coefficient curves for normal weight concrete and lean concrete were
comparable as both their porosities were in the range of 3% to 4% and their
surfaces were impermeable.
Pervious concrete versus lean concrete. Pervious concrete also had
better sound absorption capacity compared to lean concrete for the entire
frequency range. In particular, the maximum value of sound absorption
coefficients α for pervious concrete and lean concrete were 0.92 and 0.11
respectively. The lowest sound absorption coefficients for pervious concrete
and normal weight concrete were 0.40 and 0.06 respectively.
Pervious concrete versus porous asphalt. Pervious concrete had
marginally better sound absorption capacity when compared to porous asphalt.
Both their peak sound absorption coefficients occurred at the frequency of 800
Hz but their values differed. The sound absorption coefficient α value for
pervious concrete was highest at 0.92 whereas porous asphalt was at 0.83. The
sound absorption coefficient α value was lowest at 0.40 for pervious concrete
and 0.30 for porous asphalt.
127
Porous asphalt versus open-graded asphalt versus dense asphalt.
Comparing the three types of asphalt mixes, porous asphalt had better sound
absorption capacity than open-graded asphalt which in turn performed better
than dense graded asphalt. The difference in sound absorption capacity for the
three mixes could be attributed to differences in their porosities. Porous, open-
graded and dense asphalt had porosities of 20%, 10% and 3% - 4%
respectively. The peak sound absorption coefficient for porous, open-graded
and dense asphalt mixes were 0.83, 0.67 and 0.18 respectively. The lowest
sound absorption coefficient for porous, open-graded and dense asphalt mixes
were 0.30, 0.22 and 0.12 respectively.
Overall, pervious concrete had the best sound absorption capacity
amongst the eight types of mixes tested. The use of steel fibers had no effect
on the sound absorption capacity of the mix.
5.2.2 Effect of porosity (Test Series B)
Four different porosities ranging from 10% to 25% at intervals of 5%
were considered for the sound absorption tests of pervious concrete and
porous asphalt specimens respectively. Table 5.6 shows the measured porosity
of the test samples and Figures 5.7 and 5.8 show graphically the sound
absorption coefficients of pervious concrete and porous asphalt at various
frequencies. Increasing the porosity slightly increased the frequencies from
500 Hz to 600 Hz at which the maximum sound absorption occurred, for both
pervious concrete and porous asphalt.
Table 5.7 shows the peak sound absorption coefficient for pervious
concrete and porous asphalt. For both pervious concrete and porous asphalt,
128
mix with a porosity of 10% had a lower sound absorption coefficient than the
corresponding mixtures with a porosity of 15%. When the porosity increased
from 15% to 20%, there was no change in the maximum values of the sound
absorption coefficient, but there was a shift in the peaks of frequency from 500
Hz to 600 Hz.
As the porosity was increased from 20% to 25%, the maximum sound
absorption coefficient decreased. This is in line with the findings by Neithalath
et al. (2005) who researched with the porosity ranging from 15% to 35% and
indicated that the results seemed counter-intuitive. It has been experimentally
shown that an increase in pore size reduces the maximum absorption
coefficient (Marolf et al., 2004). This reduction in maximum acoustic
absorption coefficient occurs because for a system with large-size pores, the
fictional losses are low and a considerable portion of the acoustic waves that
enter the pore system gets reflected. The sound absorption coefficient (α) of
pervious concrete were higher than porous asphalt by about 0.1 throughout the
entire frequency range.
It should be noted that porosity is influenced by the pore size, pore to
aperture size ratio and pore length, in addition to aperture length, and it is the
combined effect of all these factors that result in different acoustic absorption
(Neithalath et al., 2005).
5.2.3 Effect of thickness (Test Series C)
Figure 5.9 shows the test samples with three thicknesses, 20 cm, 10 cm
and 6.3 cm. Table 5.8 records the measured sound absorption coefficients for
all the test specimens and Figure 5.10 show the variations in sound absorption
coefficients of pervious concrete and porous asphalt for various pavement
129
thicknesses. For both materials, an increase in specimen thickness led to a
reduction in the frequencies at which the maximum sound absorption
coefficient value occurred. There were very slight increases in the maximum
value of absorption coefficient.
The sound energy has been absorbed by the upper surface section of
the pervious concrete and porous asphalt and thus increasing their thickness
has marginal effect in increasing their sound absorption capacity. On the other
hand, Ahammed and Tighe (2011) who did a study on conventional dense
concrete with varying thickness of 260 mm, 200 mm and 76 mm, noted no
significant effect in sound energy absorption and concluded that increasing the
thickness of the pavement was not beneficial in terms of reducing road noise.
From Figure 5.11, the graphs show that pervious concrete had improved sound
absorption capacity as compared to porous asphalt at all target sample
thickness and frequencies.
5.2.4 Effect of clogging (Test Series D)
Table 5.9 shows the measured sound absorption coefficients for the
pervious concrete and porous asphalt samples with clogging percentage of 0%,
25%, 50%, 75% and 100%. These results are plotted in Figure 5.12. Since the
original pervious concrete and porous asphalt samples had a target porosity of
20%, the porosity of the clogged samples would correspondingly equal to
20%, 15%, 10%, 5% and 1%. For the sample that was 100% clogged, a 0%
porosity is unrealistic as not all the pores in the porous materials can be
clogged up. Three samples were tested at each clogging percentage and their
130
average values are plotted over different frequencies ranging from 100 to 2000
Hz in Figure 5.12.
Table 5.10 details the target and actual porosity of the samples and
Table 5.11 summarizes the highest α value and the frequency at which it
occurred for each porosity level. The peak value of (α) of both pervious
concrete and porous asphalt decreased with percent clogging and this is in line
with the findings of Neithalath et al. (2005). This is because sound waves
enter the matrix of the porous material through the surface pores and travel
around the pore structure; as a result, the sound energy is later converted into
heat energy. The sound energy can be said to be dampened by the porous
material. Therefore with more pores available, more sound waves can be
dampened by the porous material. As such samples with higher porosity have
higher α value.
Traffic noise caused by tire-pavement interaction occurs within the 800
Hz to 1200 Hz range (Neithalath et al., 2005 and Sandberg, 1999). From
Figure 5.12, pervious concrete and porous asphalt samples with 20% initial
porosity can still have relatively good sound absorption capacity even after
their pores are 50% clogged. This can be seen by the marginal decrease in α
value from 0.92 for the 20% porosity sample to 0.78 for the 10% porosity
sample in the case of pervious concrete, and from 0.83 to 0.67 in the case of
porous asphalt. However, further clogging beyond 50% will have a significant
reduction in sound absorption capacity. When fully clogged, the sound
absorption capacities of pervious concrete and porous asphalt were
comparable to the normal weight concrete and dense asphalt respectively.
131
5.3 Sound pressure level dB(A)
The sound pressure level equations commonly used in acoustics
calculations (Munjal, 2013; Ver and Beranek, 2006; Moser, 2009; Fahy, 2001
and Allen and Berkley, 1979) can be used to calculate the overall sound
pressure level (SPL) for each mix. The equivalent continuous A-weighted
sound pressure level (SPL), LAT of the dB(A) is defined by:
LAT = 10log10{[ (1/T) ∫ 𝑃𝐴2 (𝑡)𝑑𝑡]/𝑝𝑟𝑒𝑓
2 }𝑇
0 (5.1)
where,
PA(t) : instantaneous A-weighted SPL in Pa,
pref : reference SPL = 20 x 10-6
Pa,
T: specified time interval in seconds.
The A-weighted sound power level (PWL), LWA is defined by:
LWA = 10log10 (WA/Wref) (5.2)
where,
WA : A-weighted PWL in watts
Wref : reference (PWL), internationally agreed upon as 10-12
watts.
To evaluate traffic noise data efficiently, the overall SPL is calculated
from the A-weighted SPL at an individual centre frequency in accordance to
the 1/3 octave band spectrum as follows:
LAT (overall) = 10log10 (∑ 10𝐿𝐴𝑇,𝑖/10𝑁
𝑖=1) (5.3)
where,
N: total number of centre frequencies,
i : subscript denoting an individual centre frequency.
132
According to Sandberg and Ejsmont (2002), because human hearing
responds not linearly but logarithmically to sound stimulus, the acoustic
parameters are expressed as the logarithm to the base ten of the ratio of the
measured value to a reference quantity. The A-weighted sound level dB(A)
correlates reasonably well with the subjective response of the loudness of
traffic noise.
Using Equation 5.3, the 1/3 octave frequency sound pressure for all
test specimens in Test Series A, B, C and D are summarised in Table 5.12 and
the overall sound pressure level for the specimens are shown in Table 5.13.
Figures 5.13 to 5.16 plot the sound pressure level dB(A) for individual
frequencies of the 1/3 octave band centre frequency (ranging from 100 Hz to
2000 Hz) as well as the overall sound pressure level for the type of mix tested.
For porous asphalt, open-graded asphalt and dense graded asphalt, the LAT
values were referenced from the overall OBSI at 80 km/hr measured from
actual roads in a project with the Land Transport Authority of Singapore
(LTA). For normal weight concrete, LAT values were referenced from
(Donavan, 2011). For pervious concrete, LAT values were assumed similar to
porous asphalt, and for lean concrete, LAT values were assumed similar to
normal weight concrete.
As seen from Figure 5.13, pervious concrete and steel fiber pervious
concrete had comparable sound pressure levels of about 96 dB(A). A
comparison of sound pressure levels between pervious concrete and normal
weight concrete shows a substantial reduction of 4.8 dB(A), which is why
pervious concrete can be classified as a quiet pavement. The difference
between pervious concrete and porous asphalt was marginal at 0.3 dB(A) and
133
when comparing porous asphalt with dense graded asphalt, a significant
reduction of 4.2 dB(A) was noted and this difference in sound pressure level
can be perceived by the human ear. Comparing porous asphalt with open-
graded asphalt, there was an overall sound pressure reduction of 1.2 dB(A).
From Figure 5.14, based on the overall sound pressure levels, pervious
concrete and porous asphalt with porosity ranging from 10% to 25% are all
comparable and in the range of 95 to 96 dB(A). The T-test: Two-samples
assuming unequal variances statistical analysis was conducted and shown in
Annex B Table B-2. Based on the analysis, not all the results was accepted at
the 95% confidence level as most of their P-values were more than 0.05.
Therefore there is not sufficient evidence to reject the null hypothesis and the
results are not statistically different. The results between PC25 and PA10 can
be accepted at the 95% confidence level as the P-values were less than 0.05.
The null hypothesis was rejected in favor of the alternative hypothesis. The
difference in overall sound pressure level between pervious concrete and
porous asphalt was about 0.6 dB(A).
Figure 5.15 demonstrates that when pervious concrete and porous
asphalt sample thicknesses were varied from 63 mm to 200 mm, their overall
sound pressure levels were also in the order of 96 dB(A). That is to say,
increasing sample thickness for porous mixes does not significantly aid in
sound reduction. The sound energy would have been dissipated in the top
layer of the sample. Therefore, in terms of cost efficiency, there is little benefit
in increasing pavement surface course thickness for the purpose of noise
reduction. A T-test: Two-samples assuming unequal variances analysis was
also conducted and shown in Annex B Table B-3. Based on the analysis, not
134
all the results can be accepted at the 95% confidence level as most of their P-
values were more than 0.05. Therefore there was not sufficient evidence to
reject the null hypothesis and the results were not statistically different. The
results between PC6 and PA as well as PC6 and PA4 can be accepted at the
95% confidence level as their p-values were less than 0.05. The null
hypothesis was rejected in favor of the alternative hypothesis. The difference
in overall sound pressure level between pervious concrete and porous asphalt
was in the range of 0.3 to 0.4 dB(A).
Figure 5.16 shows that when fully clogged, pervious concrete and
porous asphalt had comparable overall sound pressure level results of 97.1
dB(A) and 97.3 dB(A) respectively. The effect of clogging on noise reduction
is not significant. After fully clogged, the sound pressure levels of both
pervious concrete and porous asphalt were increased by only 1 dB(A).
5.4 Summary
Comparing the sound absorption capacity, pervious concrete
performed slightly better than porous asphalt and open-graded asphalt, and
significantly better than dense graded asphalt, normal weight concrete and
lean concrete. The use of steel fibers in either pervious concrete or normal
weight concrete had no effect on their sound absorption capacities.
An increase in porous specimen porosity and thickness did not
significantly aid in improving sound absorption capacity. Clogging affected
the sound absorption capacities of both pervious concrete and porous asphalt
in the order of about 1 dB(A) increment even when they were fully clogged.
135
Other researchers (Luong et al., 2014; Gonzalez et al., 2013;
Izevbekhai, 2011; Ahammed and Tighe, 2011; Kim and Lee, 2010; Seddeq,
2009; Park et al.,2005; Tiwari et al., 2004 and Neithalath et al., 2005) have
researched on pervious concrete and porous asphalt separately. The current
study is of significance as it makes a comparison of both the sound absorption
capacity and sound pressure level dB(A) for both pervious concrete and
porous asphalt.
136
Table 5.1 Sound Absorption Test Program
Series Test
Variable Type
Mix
ID
Sample
Thickness
(mm)
Target
Porosity
(%)
Remarks
A
Type of
Pavement
Material
Pervious
Concrete PC
63
20 -
Pervious
Concrete PF 20
2% 5D
steel fiber
Normal weight
Concrete NC 1-2
Mix
commonly
used on
roads - No
Steel fiber
Normal weight
Concrete NF 1-2
2% 5D
steel fiber
Lean Concrete LC 1-2 -
Dense Asphalt NA 3-4
W3B -
Mix
commonly
used on
roads
Open-graded
Asphalt OG 10
OGW-
Mix
commonly
used on
roads
Porous Asphalt PA 20 -
B
Porosity of
Pavement
Material
Pervious
Concrete
PC10
63
10 -
PC15 15
PC20 20
Same as
PC
(Series A)
PC25 25 -
Open-graded
Asphalt
PA10 10
Same as
OG
(Series A)
PA15 15 -
Porous Asphalt PA20 20
Same as
PA
(Series A)
PA25 25 -
C
Thickness
of
Pavement
Layer
Pervious
Concrete
PC 63
20
Same as
PC
(Series A)
PC4 100 -
PC6 200
Porous Asphalt
PA 63
20
Same as
PA
(Series A)
PA4 100 -
PA6 200
137
Table 5.1 Sound Absorption Test Program (Cont’d)
Series
Test Variable Type
Sample
Thickness
(mm)
Target
Porosity
(%)
Remarks
D
Degree of
Clogging
Pervious
Concrete
50
20 0% clogged
15 25% clogged
10 50% clogged
5 75% clogged
2-3 100% clogged
Porous
Asphalt
20 0% clogged
15 25% clogged
10 50% clogged
5 75% clogged
2-3 100% clogged
138
Table 5.2 Gradation analysis for coarse and fine aggregates
Mix Small Coarse Aggregate
Fine
aggregate Pervious
concrete
Normal weight
concrete
Lean
Concrete
Sieve
Size (% passing) (% passing) (% passing) (% passing)
25 mm - - 100 -
19 mm - - 85 -
9.5 mm 95 95 - -
4.75 mm 38 38 50 95
2.36 mm 18 18 - 80
1.18 mm 5 5 - 65
0.60 mm - - - 58
0.475
mm - - 23 -
0.30 mm 3 3 - 38
0.15 mm - - - 8
0.075
mm - - 8 -
Pan 0 0 0 0
139
Table 5.3 Mix proportions of concrete samples
Mix
Target
Porosity
Level
[%]
Water/
Cement
Ratio
Cement
[kg/m3]
Water
[kg/m3]
Coarse
Aggregate
[kg/m3]
Sand
[kg/m3]
5D Steel
fibers
dosage
[%]
PC 10 10
0.3
495 148.5
1560 -
-
PC 15 15 400 120.0
PC 20
(Reference) 20 367 110.1
PC 25 25 300 90.0
Steel fiber
pervious
concrete
(PF)
20 367 110.1 2.0
Normal
weight
concrete
(NC)
3-4
0.4 430 172 437.6 705.9
-
Steel fiber
normal
weight
concrete
(NF)
2.0
Lean
concrete
(LC)
1.1 220 242 1143.5 - -
140
Table 5.4 Aggregate gradation and mix composition of asphalt mix designs
Mix Design
Dense graded
Asphalt
W3B
Porous
Asphalt
PA-13
Porous
Asphalt
PA-16
Porous
Asphalt
PA-20
Sieve Size (% passing) (% passing) (% passing) (% passing)
20 mm 100 - - 100
16 mm - - 100 95
13.2 mm 90 100 70 85
9.5 mm - 85 59 72
6.3 mm 63 - - -
4.75 mm - 45 33 22
3.35mm 45 - - -
2.36mm - 30 22 18
1.18mm 26 25 16 -
600um - 20 10 13
300um 14 13 6 9
150um - 10 4 7
75um 6 4 3 6
Asphalt Binder
Content (% by
Weight of
Total Mix)
4.5 to 5.5
Air void
content (%) 3 to 4 8 to 12 15 to 20 20 to 25 or
more
141
Table 5.5 Measured sound absorption coefficients for Series A with different
material types
Frequency
(Hz)
Sound absorption coefficient (α) – PC and PF
PC-1 PC-2 PC-3 Average PF-1 PF-2 PF-3 Average
100 0.38 0.43 0.4 0.40 0.41 0.37 0.37 0.38
150 0.47 0.42 0.41 0.43 0.43 0.39 0.41 0.41
200 0.43 0.46 0.45 0.45 0.45 0.41 0.42 0.43
250 0.46 0.48 0.43 0.46 0.45 0.42 0.43 0.44
300 0.52 0.53 0.5 0.52 0.47 0.43 0.44 0.45
350 0.51 0.54 0.47 0.51 0.51 0.46 0.49 0.49
400 0.59 0.57 0.52 0.56 0.57 0.50 0.55 0.54
500 0.66 0.7 0.65 0.67 0.67 0.62 0.65 0.65
600 0.79 0.78 0.74 0.77 0.76 0.73 0.75 0.75
700 0.9 0.85 0.88 0.88 0.88 0.83 0.85 0.86
800 0.93 0.91 0.92 0.92 0.93 0.88 0.90 0.90
900 0.75 0.7 0.67 0.71 0.70 0.67 0.69 0.69
1000 0.63 0.58 0.56 0.59 0.58 0.55 0.57 0.57
1250 0.55 0.53 0.5 0.53 0.52 0.49 0.50 0.51
1500 0.53 0.5 0.46 0.50 0.52 0.46 0.45 0.48
1750 0.48 0.47 0.44 0.46 0.48 0.40 0.44 0.44
2000 0.5 0.46 0.46 0.47 0.47 0.42 0.47 0.45
142
Table 5.5 Measured sound absorption coefficients for Series A with different
material types (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – NC and NF
NC-1 NC-2 NC-3 Average NF-1 NF-2 NF-3 Average
100 0.11 0.10 0.09 0.10 0.10 0.09 0.06 0.08
150 0.11 0.12 0.10 0.11 0.11 0.10 0.08 0.10
200 0.10 0.09 0.08 0.09 0.10 0.06 0.05 0.07
250 0.12 0.13 0.11 0.12 0.12 0.09 0.09 0.10
300 0.11 0.13 0.09 0.11 0.11 0.09 0.08 0.09
350 0.11 0.11 0.08 0.10 0.09 0.10 0.05 0.08
400 0.10 0.09 0.08 0.09 0.08 0.07 0.05 0.07
500 0.07 0.05 0.06 0.06 0.07 0.06 0.03 0.05
600 0.09 0.08 0.07 0.08 0.08 0.06 0.05 0.06
700 0.07 0.06 0.05 0.06 0.07 0.04 0.04 0.05
800 0.11 0.10 0.09 0.10 0.11 0.06 0.07 0.08
900 0.11 0.12 0.10 0.11 0.10 0.09 0.07 0.09
1000 0.12 0.10 0.09 0.10 0.10 0.08 0.06 0.08
1250 0.12 0.12 0.09 0.11 0.11 0.09 0.07 0.09
1500 0.12 0.10 0.09 0.10 0.10 0.08 0.06 0.08
1750 0.12 0.11 0.10 0.11 0.11 0.09 0.07 0.09
2000 0.11 0.09 0.07 0.09 0.09 0.07 0.05 0.07
143
Table 5.5 Measured sound absorption coefficients for Series A with different
material types (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – LC and NA
LC-1 LC-2 LC-3 Average NA-1 NA-2 NA-3 Average
100 0.11 0.09 0.07 0.09 0.15 0.09 0.09 0.11
150 0.11 0.10 0.08 0.10 0.17 0.1 0.09 0.12
200 0.11 0.07 0.06 0.08 0.16 0.13 0.16 0.15
250 0.11 0.12 0.10 0.11 0.2 0.16 0.12 0.16
300 0.10 0.11 0.09 0.10 0.13 0.11 0.15 0.13
350 0.10 0.11 0.06 0.09 0.21 0.14 0.13 0.16
400 0.10 0.08 0.06 0.08 0.22 0.16 0.16 0.18
500 0.07 0.06 0.03 0.05 0.17 0.15 0.19 0.17
600 0.09 0.07 0.06 0.07 0.2 0.16 0.18 0.18
700 0.07 0.04 0.04 0.05 0.25 0.17 0.18 0.2
800 0.12 0.07 0.08 0.09 0.24 0.13 0.2 0.19
900 0.11 0.10 0.08 0.10 0.22 0.15 0.14 0.17
1000 0.11 0.09 0.07 0.09 0.15 0.1 0.23 0.16
1250 0.11 0.11 0.08 0.10 0.18 0.17 0.16 0.17
1500 0.10 0.09 0.07 0.09 0.16 0.11 0.12 0.13
1750 0.12 0.10 0.08 0.10 0.2 0.15 0.07 0.14
2000 0.10 0.08 0.06 0.08 0.18 0.13 0.08 0.13
144
Table 5.5 Measured sound absorption coefficients for Series A with different
material types (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – OG and PA
OG-1 OG-2 OG-3 Average PA-1 PA-2 PA-3 Average
100 0.24 0.20 0.22 0.22 0.33 0.28 0.30 0.30
150 0.32 0.29 0.30 0.30 0.41 0.35 0.35 0.37
200 0.39 0.34 0.35 0.36 0.39 0.36 0.38 0.38
250 0.39 0.35 0.36 0.37 0.40 0.35 0.38 0.38
300 0.45 0.37 0.41 0.41 0.43 0.40 0.42 0.42
350 0.46 0.40 0.43 0.43 0.48 0.41 0.45 0.45
400 0.50 0.46 0.48 0.48 0.52 0.45 0.50 0.49
500 0.61 0.53 0.59 0.58 0.62 0.57 0.58 0.59
600 0.71 0.65 0.64 0.67 0.70 0.65 0.69 0.68
700 0.60 0.56 0.58 0.58 0.80 0.75 0.78 0.78
800 0.54 0.50 0.51 0.52 0.85 0.80 0.83 0.83
900 0.50 0.45 0.48 0.48 0.60 0.52 0.55 0.56
1000 0.46 0.40 0.43 0.43 0.55 0.48 0.50 0.51
1250 0.40 0.35 0.40 0.38 0.53 0.40 0.46 0.46
1500 0.40 0.36 0.36 0.37 0.45 0.38 0.42 0.42
1750 0.37 0.33 0.34 0.35 0.40 0.36 0.39 0.38
2000 0.33 0.26 0.32 0.30 0.35 0.31 0.33 0.33
145
Table 5.6 Porosity of specimens for Series B on materials type
Target
Porosity
(%)
Measured Porosity (%)
Pervious Concrete Porous Asphalt
10 Average (11.5, 12.9, 13.2) = 12.5 Average (11.9, 12.3, 13.1) =12.4
15 Average (16.23, 17.14, 17.86) = 17.1 Average (16.1, 16.8, 17.3) =16.7
20 Average (20.31, 21.56, 22.05) = 21.3 Average (20.9, 21.8, 22.0) = 21.5
25 Average (25.13, 25.41, 26.05) = 25.5 Average (25.4, 25.9, 26.1) = 25.8
Table 5.7 Peak sound absorption coefficient for pervious concrete and porous
asphalt specimens for Series B test with different porosities
Porosity
(%)
Peak sound absorption coefficient (α)
Pervious Concrete Porous Asphalt
10 0.80 at 500 Hz 0.75 at 500 Hz
15 0.93 at 500 Hz 0.83 at 500 Hz
20 0.92 at 600 Hz 0.82 at 600 Hz
25 0.84 at 600 Hz 0.77 at 600 Hz
146
Table 5.8 Measured sound absorption coefficients for Series C with different
thicknesses of pavement layer
Frequency
(Hz)
Sound absorption coefficient (α) – thickness: 63 mm
PC-1 PC-2 PC-3 Average PA-1 PA-2 PA-3 Average
100 0.40 0.35 0.37 0.37 0.3 0.32 0.35 0.32
150 0.43 0.37 0.39 0.40 0.41 0.35 0.37 0.38
200 0.46 0.41 0.41 0.43 0.36 0.39 0.38 0.38
250 0.43 0.38 0.40 0.40 0.33 0.38 0.35 0.35
300 0.51 0.45 0.44 0.47 0.42 0.43 0.4 0.42
350 0.53 0.46 0.50 0.50 0.45 0.48 0.41 0.45
400 0.57 0.50 0.55 0.54 0.52 0.5 0.45 0.49
500 0.83 0.70 0.77 0.77 0.68 0.62 0.55 0.62
600 0.92 0.85 0.85 0.87 0.8 0.85 0.82 0.82
700 0.85 0.75 0.80 0.80 0.75 0.7 0.8 0.75
800 0.70 0.64 0.68 0.67 0.6 0.62 0.65 0.62
900 0.60 0.54 0.58 0.57 0.55 0.5 0.52 0.52
1000 0.53 0.47 0.50 0.50 0.45 0.42 0.4 0.42
1250 0.50 0.42 0.45 0.46 0.4 0.45 0.37 0.41
1500 0.44 0.38 0.38 0.40 0.33 0.36 0.36 0.35
1750 0.39 0.34 0.36 0.36 0.28 0.31 0.26 0.28
2000 0.42 0.34 0.38 0.38 0.33 0.32 0.35 0.33
147
Table 5.8 Measured sound absorption coefficients for Series C with different
thicknesses of pavement layer (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – thickness: 100 mm
PC4-1 PC4-2 PC4-3 Average PA4-1 PA4-2 PA4-3 Average
100 0.34 0.27 0.36 0.32 0.25 0.26 0.28 0.26
150 0.42 0.34 0.39 0.38 0.36 0.31 0.3 0.32
200 0.41 0.34 0.39 0.38 0.28 0.33 0.35 0.32
250 0.46 0.37 0.40 0.41 0.42 0.31 0.32 0.35
300 0.60 0.48 0.54 0.54 0.62 0.47 0.36 0.48
350 0.75 0.61 0.72 0.69 0.71 0.64 0.55 0.63
400 0.90 0.83 0.82 0.85 0.8 0.8 0.77 0.79
500 0.91 0.86 0.89 0.89 0.83 0.85 0.8 0.83
600 0.84 0.79 0.82 0.82 0.76 0.79 0.81 0.79
700 0.78 0.71 0.74 0.74 0.68 0.65 0.72 0.68
800 0.66 0.56 0.61 0.61 0.41 0.57 0.67 0.55
900 0.54 0.41 0.46 0.47 0.35 0.4 0.48 0.41
1000 0.45 0.35 0.39 0.40 0.26 0.3 0.36 0.31
1250 0.36 0.29 0.34 0.33 0.25 0.26 0.3 0.27
1500 0.34 0.28 0.27 0.30 0.22 0.24 0.25 0.24
1750 0.36 0.30 0.34 0.33 0.26 0.3 0.32 0.29
2000 0.49 0.41 0.44 0.45 0.38 0.35 0.43 0.39
148
Table 5.8 Measured sound absorption coefficients for Series C with different
thicknesses of pavement layer (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – thickness: 200 mm
PC6-1 PC6-2 PC6-3 Average PA6-1 PA6-2 PA6-3 Average
100 0.34 0.31 0.31 0.32 0.25 0.28 0.25 0.26
150 0.57 0.47 0.52 0.52 0.56 0.36 0.46 0.46
200 0.77 0.70 0.72 0.73 0.76 0.66 0.6 0.67
250 0.94 0.89 0.89 0.91 0.85 0.86 0.83 0.85
300 0.90 0.86 0.89 0.88 0.84 0.83 0.8 0.82
350 0.88 0.80 0.82 0.83 0.76 0.7 0.68 0.71
400 0.83 0.72 0.79 0.78 0.74 0.6 0.65 0.66
500 0.66 0.61 0.63 0.63 0.6 0.55 0.57 0.57
600 0.58 0.52 0.55 0.55 0.5 0.5 0.48 0.49
700 0.54 0.46 0.51 0.50 0.45 0.48 0.4 0.44
800 0.50 0.46 0.49 0.48 0.4 0.41 0.37 0.39
900 0.49 0.39 0.47 0.45 0.4 0.38 0.3 0.36
1000 0.48 0.41 0.49 0.46 0.35 0.45 0.4 0.40
1250 0.46 0.40 0.40 0.42 0.3 0.33 0.32 0.32
1500 0.46 0.39 0.37 0.41 0.29 0.35 0.4 0.35
1750 0.39 0.33 0.37 0.36 0.27 0.33 0.31 0.30
2000 0.36 0.32 0.33 0.34 0.26 0.27 0.3 0.28
149
Table 5.9 Target porosity and measured porosity of the samples for Series D
with different degrees of clogging
Target
Porosity (%)
Pervious Concrete Porous Asphalt
Measured
Porosity (%)
Mean
Porosity (%)
Measured
Porosity (%)
Mean
Porosity (%)
20
20.15
20.64
20.60
19.53 22.35 19.01
19.41 18.97
15
14.68
14.88
14.46
14.21 16.01 14.20
13.95 13.96
10
9.96
9.54
9.09
9.08 10.46 8.97
8.19 9.19
5
6.45
6.27
4.16
4.77 6.03 5.42
6.33 4.72
1
1.86
1.83
1.79
1.62 1.67 1.59
1.97 1.47
150
Table 5.10 Measured sound absorption coefficients for Series D with different
degrees of clogging
Frequency
(Hz)
Sound absorption coefficient (α) – 0% clogged
PC-1 PC-2 PC-3 Average PA-1 PA-2 PA-3 Average
100 0.38 0.43 0.4 0.40 0.28 0.33 0.3 0.30
150 0.47 0.42 0.41 0.43 0.41 0.35 0.35 0.37
200 0.43 0.46 0.45 0.45 0.36 0.39 0.38 0.38
250 0.46 0.48 0.43 0.46 0.38 0.4 0.35 0.38
300 0.52 0.53 0.5 0.52 0.42 0.43 0.4 0.42
350 0.51 0.54 0.47 0.51 0.45 0.48 0.41 0.45
400 0.59 0.57 0.52 0.56 0.52 0.5 0.45 0.49
500 0.66 0.7 0.65 0.67 0.58 0.62 0.57 0.59
600 0.79 0.78 0.74 0.77 0.7 0.69 0.65 0.68
700 0.9 0.85 0.88 0.88 0.8 0.75 0.78 0.78
800 0.93 0.91 0.92 0.92 0.85 0.83 0.8 0.83
900 0.75 0.7 0.67 0.71 0.6 0.55 0.52 0.56
1000 0.63 0.58 0.56 0.59 0.55 0.5 0.48 0.51
1250 0.55 0.53 0.5 0.53 0.53 0.46 0.4 0.46
1500 0.53 0.5 0.46 0.50 0.45 0.42 0.38 0.42
1750 0.48 0.47 0.44 0.46 0.4 0.39 0.36 0.38
2000 0.5 0.46 0.48 0.48 0.35 0.31 0.33 0.33
151
Table 5.10 Measured sound absorption coefficients for Series D with different
degrees of clogging (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – 25% clogged
PC-1 PC-2 PC-3 Average PA-1 PA-2 PA-3 Average
100 0.35 0.37 0.34 0.35 0.27 0.29 0.26 0.27
150 0.39 0.41 0.38 0.39 0.33 0.35 0.32 0.33
200 0.42 0.47 0.43 0.44 0.35 0.4 0.36 0.37
250 0.44 0.5 0.48 0.47 0.36 0.42 0.4 0.39
300 0.5 0.54 0.52 0.52 0.4 0.44 0.42 0.42
350 0.5 0.56 0.53 0.53 0.42 0.48 0.45 0.45
400 0.57 0.56 0.55 0.56 0.5 0.49 0.48 0.49
500 0.63 0.68 0.68 0.66 0.55 0.6 0.6 0.58
600 0.79 0.75 0.8 0.78 0.7 0.66 0.64 0.67
700 0.85 0.8 0.83 0.83 0.75 0.7 0.73 0.73
800 0.74 0.7 0.73 0.72 0.66 0.62 0.6 0.63
900 0.69 0.61 0.6 0.63 0.58 0.5 0.49 0.52
1000 0.58 0.53 0.51 0.54 0.5 0.45 0.43 0.46
1250 0.51 0.49 0.48 0.49 0.44 0.42 0.38 0.41
1500 0.47 0.48 0.45 0.47 0.39 0.4 0.37 0.39
1750 0.46 0.43 0.43 0.44 0.38 0.35 0.35 0.36
2000 0.43 0.42 0.44 0.43 0.32 0.31 0.33 0.32
152
Table 5.10 Measured sound absorption coefficients for Series D with different
degrees of clogging (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – 50% clogged
PC-1 PC-2 PC-3 Average PA-1 PA-2 PA-3 Average
100 0.31 0.34 0.33 0.33 0.2 0.22 0.24 0.22
150 0.38 0.4 0.37 0.38 0.3 0.32 0.29 0.30
200 0.41 0.46 0.42 0.43 0.34 0.39 0.35 0.36
250 0.44 0.43 0.47 0.45 0.36 0.35 0.39 0.37
300 0.51 0.5 0.52 0.51 0.41 0.4 0.42 0.41
350 0.52 0.58 0.55 0.55 0.4 0.46 0.43 0.43
400 0.55 0.57 0.57 0.56 0.48 0.5 0.46 0.48
500 0.61 0.69 0.67 0.66 0.53 0.61 0.59 0.58
600 0.77 0.76 0.81 0.78 0.68 0.67 0.65 0.67
700 0.7 0.68 0.66 0.68 0.6 0.58 0.56 0.58
800 0.64 0.61 0.6 0.62 0.54 0.51 0.5 0.52
900 0.61 0.56 0.59 0.59 0.5 0.45 0.48 0.48
1000 0.54 0.51 0.48 0.51 0.46 0.43 0.4 0.43
1250 0.47 0.47 0.45 0.46 0.4 0.4 0.35 0.38
1500 0.44 0.48 0.44 0.45 0.36 0.4 0.36 0.37
1750 0.38 0.44 0.34 0.39 0.37 0.34 0.33 0.35
2000 0.38 0.35 0.33 0.35 0.33 0.3 0.28 0.30
153
Table 5.10 Measured sound absorption coefficients for Series D with different
degrees of clogging (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – 75% clogged
PC-1 PC-2 PC-3 Average PA-1 PA-2 PA-3 Average
100 0.26 0.24 0.21 0.24 0.23 0.21 0.18 0.21
150 0.31 0.32 0.28 0.30 0.25 0.26 0.22 0.24
200 0.31 0.35 0.33 0.33 0.24 0.28 0.26 0.26
250 0.38 0.38 0.33 0.36 0.3 0.3 0.25 0.28
300 0.41 0.39 0.38 0.39 0.31 0.29 0.28 0.29
350 0.44 0.45 0.45 0.45 0.32 0.33 0.33 0.33
400 0.43 0.44 0.47 0.45 0.36 0.35 0.38 0.36
500 0.46 0.48 0.5 0.48 0.38 0.4 0.42 0.40
600 0.44 0.45 0.47 0.45 0.35 0.36 0.37 0.36
700 0.4 0.43 0.4 0.41 0.3 0.33 0.3 0.31
800 0.38 0.4 0.35 0.38 0.28 0.3 0.25 0.28
900 0.4 0.38 0.33 0.37 0.29 0.27 0.22 0.26
1000 0.33 0.36 0.31 0.33 0.25 0.28 0.23 0.25
1250 0.33 0.31 0.32 0.32 0.26 0.24 0.22 0.24
1500 0.33 0.3 0.28 0.30 0.25 0.25 0.2 0.23
1750 0.26 0.29 0.24 0.26 0.25 0.24 0.19 0.23
2000 0.26 0.25 0.22 0.24 0.24 0.23 0.2 0.22
154
Table 5.10 Measured sound absorption coefficients for Series D with different
degrees of clogging (Cont’d)
Frequency
(Hz)
Sound absorption coefficient (α) – 100% clogged
PC-1 PC-2 PC-3 Average PA-1 PA-2 PA-3 Average
100 0.2 0.19 0.18 0.19 0.15 0.13 0.12 0.13
150 0.22 0.22 0.2 0.21 0.16 0.14 0.15 0.15
200 0.25 0.22 0.23 0.23 0.18 0.15 0.16 0.16
250 0.27 0.27 0.25 0.26 0.21 0.19 0.17 0.19
300 0.28 0.26 0.27 0.27 0.21 0.18 0.2 0.20
350 0.29 0.29 0.26 0.28 0.2 0.2 0.22 0.21
400 0.3 0.29 0.29 0.29 0.23 0.22 0.24 0.23
500 0.28 0.27 0.27 0.27 0.2 0.19 0.22 0.20
600 0.27 0.26 0.25 0.26 0.18 0.17 0.2 0.18
700 0.29 0.28 0.26 0.28 0.19 0.18 0.21 0.19
800 0.28 0.26 0.24 0.26 0.18 0.16 0.19 0.18
900 0.28 0.25 0.23 0.25 0.17 0.16 0.18 0.17
1000 0.24 0.2 0.25 0.23 0.16 0.14 0.18 0.16
1250 0.22 0.22 0.23 0.22 0.15 0.15 0.16 0.15
1500 0.24 0.23 0.25 0.24 0.16 0.16 0.17 0.16
1750 0.18 0.2 0.19 0.19 0.15 0.17 0.14 0.15
2000 0.19 0.2 0.18 0.19 0.14 0.15 0.13 0.14
155
Table 5.11 Peak α values for different porosity and the frequency that they
occur at for clogging series D
Final target
porosity
(%)
Percentage
clogging
(%)
Pervious
concrete
peak
sound
absorption
coefficient
(α)
Porous
asphalt
peak
sound
absorption
coefficient
(α)
Frequency at
which peak α
occurs
(Hz)
20 0 0.92 0.83 800
15 25 0.83 0.78 700
10 50 0.78 0.69 600
5 75 0.48 0.40 500
1 100 0.29 0.22 400
156
Table 5.12 1/3 octave frequency sound pressures for all test specimens (Series
A, B, C and D)
Type of
Pavement
Material
(Series A)
1/3 octave band centre frequency sound pressure dB(A)
Frequency (Hz) PC PF NC NF LC NA OG PA
100 68.0 68.1 73.8 73.8 73.8 67.3 67.5 68.3
125 75.6 75.7 74.8 74.8 74.8 73.2 74.2 75.9
160 76.8 76.9 75.8 75.8 75.8 75.6 75.8 77.0
200 80.6 80.6 77.8 77.9 77.8 82.7 81.2 80.8
250 83.1 83.1 78.7 78.8 78.8 83.8 83.0 83.3
315 85.4 85.6 79.7 79.8 79.8 85.1 84.7 85.7
400 86.6 86.6 80.8 80.8 80.8 86.2 85.8 86.8
500 90.0 90.1 83.9 83.9 83.9 89.8 89.1 90.3
630 87.0 87.1 85.8 85.9 85.9 90.9 88.3 87.4
800 85.3 85.4 93.8 93.8 93.8 92.1 88.7 85.7
1000 85.2 85.3 95.8 95.8 95.8 93.4 88.9 85.4
1250 84.1 84.2 91.8 91.8 91.8 92.2 87.9 84.3
1600 83.0 83.1 93.8 93.8 93.8 91.1 86.7 83.2
2000 81.8 81.8 89.8 89.9 89.9 89.8 85.6 82.1
Porosity of
Pavement
Material
(Series B)
1/3 Octave band centre frequency sound pressure dB(A)
Frequency (Hz) PC10 PC15 PC20 PC25 PA10 PA15 PA20 PA25
100 68.2 68.0 68.1 68.2 68.3 68.2 68.4 68.5
125 75.7 75.5 75.7 75.8 75.9 75.8 76.0 76.0
160 76.9 76.7 76.9 76.9 77.0 77.0 77.2 77.2
200 80.4 80.5 80.6 80.6 80.8 80.8 80.8 80.9
250 82.9 83.0 83.0 83.1 83.1 83.2 83.3 83.4
315 85.3 85.4 85.4 85.4 85.4 85.6 85.6 85.7
400 85.9 85.7 86.5 86.5 86.2 86.1 86.5 86.8
500 89.6 89.1 90.0 90.0 89.7 89.4 90.2 90.3
630 87.2 87.0 86.6 87.3 87.4 87.4 87.0 87.2
800 86.3 86.3 86.0 86.3 86.5 86.6 86.3 86.7
1000 85.6 85.3 85.3 85.4 85.8 85.7 85.6 85.7
1250 84.4 84.1 84.2 84.3 84.6 84.5 84.5 84.6
1600 83.2 82.9 83.0 83.1 83.5 83.3 83.3 83.4
2000 82.0 81.6 81.9 82.1 82.2 82.0 82.1 82.2
157
Table 5.12 1/3 octave frequency sound pressures for all test specimens (Series
A, B, C and D) (Cont’d)
Thickness of
Pavement Layer
(Series C)
1/3 octave band centre frequency sound pressure dB(A)
Frequency (Hz) PC PC 4 PC 6 PA PA 4 PA 6
100 68.1 68.3 68.3 68.3 68.4 68.4
125 75.7 75.8 75.8 75.8 76.0 76.0
160 76.9 77.0 76.5 77.0 77.1 76.7
200 80.6 80.8 79.7 80.8 80.9 79.9
250 83.2 83.2 81.6 83.4 83.4 81.8
315 85.5 85.3 84.3 85.7 85.5 84.5
400 86.6 85.6 85.8 86.8 85.8 86.2
500 89.7 89.2 90.1 90.2 89.5 90.3
630 86.9 87.0 87.9 86.9 87.1 88.1
800 86.2 86.4 86.8 86.4 86.6 87.0
1000 85.5 85.8 85.6 85.7 86.0 85.8
1250 84.3 84.7 84.4 84.5 84.8 84.7
1600 83.3 83.5 83.2 83.4 83.6 83.4
2000 82.0 81.8 82.1 82.1 82.0 82.3
158
Table 5.12 1/3 octave frequency sound pressures for all test specimens (Series
A, B, C and D) (Cont’d)
Degree of
Clogging -
Pervious
Concrete
(Series D)
1/3 octave band centre frequency sound pressure dB(A)
Frequency
(Hz) PC 0% PC 25% PC 50% PC 75% PC 100%
100 68.0 68.2 68.2 68.5 68.6
125 75.6 75.7 75.8 76.0 76.2
160 76.8 76.9 76.9 77.1 77.4
200 80.6 80.6 80.6 80.9 81.1
250 83.1 83.0 83.1 83.3 83.6
315 85.4 85.4 85.4 85.8 86.1
400 86.6 86.6 86.6 86.9 87.3
500 90.0 90.0 90.1 90.6 91.1
630 87.1 87.1 87.1 88.2 88.6
800 85.3 86.0 86.4 87.1 87.4
1000 85.2 85.4 85.4 85.9 86.2
1250 84.1 84.2 84.3 84.7 84.9
1600 83.0 83.1 83.2 83.6 83.7
2000 81.7 81.9 82.1 82.4 82.5
Degree of
Clogging -
Porous
Asphalt
(Series D)
1/3 octave band centre frequency sound pressure dB(A)
Frequency
(Hz) PA 0% PA 25% PA 50% PA 75% PA 100%
100 68.3 68.4 68.5 68.5 68.7
125 75.9 75.9 76.1 76.1 76.3
160 77.0 77.1 77.1 77.3 77.5
200 80.8 80.8 80.8 81.1 81.3
250 83.3 83.2 83.3 83.5 83.8
315 85.7 85.7 85.7 86.0 86.3
400 86.8 86.8 86.8 87.1 87.5
500 90.3 90.3 90.3 90.8 91.3
630 87.4 87.5 87.5 88.4 88.8
800 85.7 86.4 86.7 87.3 87.6
1000 85.4 85.6 85.7 86.1 86.4
1250 84.3 84.5 84.5 84.9 85.1
1600 83.2 83.3 83.3 83.6 83.9
2000 82.1 82.2 82.2 82.4 82.6
159
Table 5.13 Overall sound pressures for all specimens (Series A, B, C and D)
Type of Pavement Material (Series A) Overall sound pressure dB(A)
PC 96.0
PF 96.1
NC 100.8
NF 100.8
LC 100.8
NA 100.5
OG 97.4
PA 96.3
Porosity of Pavement Material (Series B) Overall sound pressure dB(A)
PC10 96.2
PC15 96.0
PC20 96.0
PC25 95.8
PA10 96.4
PA15 96.3
PA20 96.2
PA25 96.1
Thickness of Pavement Layer (Series C) Overall sound pressure dB(A)
PC 96.1
PC 4 96.1
PC 6 96.0
PA 96.4
PA 4 96.3
PA 6 96.2
Degree of Clogging (Series D) Overall sound pressure dB(A)
PC 0% 96.0
PC 25% 96.1
PC 50% 96.2
PC 75% 96.7
PC 100% 97.1
PA 0% 96.3
PA 25% 96.4
PA 50% 96.5
PA 75% 96.9
PA 100% 97.3
160
(a) 100 mm diameter sample
(b) 150 mm diameter sample
Figure 5.1 Sample holder for acoustic absorption tests
ϕ 100 mm
ϕ 150 mm
161
(a) 0% clogged (b) 25% clogged
(Final target porosity of 20%) (Final target porosity of 15%)
(c) 50% clogged (d) 75% clogged
(Final target porosity of 10%) (Final target porosity of 5%)
(e) 100% clogged
(Final target porosity of 0%)
Figure 5.2 Pervious concrete samples – (a) 0% clogged; (b) 25% clogged;
(c) 50% clogged; (d) 75% clogged; (e) 100% clogged
162
(a) 0% clogged (b) 25% clogged
(Final target porosity of 20%) (Final target porosity of 15%)
(c) 50% clogged (d) 75% clogged
(Final target porosity of 10%) (Final target porosity of 5%)
(e) 100% clogged
(Final target porosity of 0%)
Figure 5.3 Porous asphalt samples – (a) 0% clogged; (b) 25% clogged;
(c) 50% clogged; (d) 75% clogged; (e) 100% clogged
163
(a)
(b)
Figure 5.4 (a) Impedance tube setup for frequencies 100 -500 Hz;
(b) Impedance tube setup for frequencies 600 - 2000 Hz
164
Figure 5.5 Low and high frequency sound waves
Note: PC = Pervious concrete; PF = Steel fiber reinforced pervious concrete; NC =
Normal weight concrete; NF = Steel fiber reinforced normal weight concrete; LC =
Lean concrete; PA = Porous asphalt; OG = Open-graded asphalt and NA = Dense
asphalt.
Figure 5.6 Sound absorption coefficient values for eight road materials
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
NC NF LCPC PF NAOG PA
Low frequency
sound wave
Impedance tube
diameter (100 mm)
High frequency
sound wave
Impedance tube
diameter (29 mm)
165
(a) Pervious Concrete
(b) Porous Asphalt
Figure 5.7 Sound absorption coefficient values for (a) pervious concrete (b)
porous asphalt at varying porosities in Test Series B
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
So
un
d A
bso
rpti
on
Co
effi
cien
t (α
)
Frequency (Hz)
PC10 PC15
PC20 PC25
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
PA10 PA15
PA20 PA25
166
(a) Pervious Concrete and Porous Asphalt with Porosity 10%
(b) Pervious Concrete and Porous Asphalt with Porosity 15%
Figure 5.8 Comparison of sound absorption coefficient values for pervious
concrete and porous asphalt at individual target porosities in Test
Series B
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
PC10 PA10
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
PC15 PA15
167
(c) Pervious Concrete and Porous Asphalt with Porosity 20%
(d) Pervious Concrete and Porous Asphalt with Porosity 25%
Figure 5.8 Comparison of sound absorption coefficient values for pervious
concrete and porous asphalt at individual target porosities in Test
Series B (Cont’d)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
PC20 PA20
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
PC25 PA25
168
Figure 5.9 Sample thicknesses
(a) 200 mm
(b) 100 mm
(c) 63 mm
169
Note: PC = 63 mm; PC 4 = 100 mm and PC 6 = 200 mm.
(a) Pervious concrete
Note: PA = 63 mm; PA 4 = 100 mm and PA 6 = 200 mm.
(b) Porous Asphalt
Figure 5.10 Sound absorption coefficient values for pervious concrete and
porous asphalt at different thicknesses in Test Series C
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound a
bso
rpti
on c
oef
fici
ent
(α)
Frequency (Hz)
PC
PC 4
PC 6
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound a
bso
rpti
on c
oef
fici
ent
(α)
Frequency (Hz)
PA
PA 4
PA 6
170
(a) Thickness = 63 mm
(b) Thickness = 100 mm
Figure 5.11 Comparison of pervious concrete and porous asphalt by thickness
in Test Series C
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound a
bso
rpti
on c
oef
fici
ent
(α)
Frequency (Hz)
PA PC
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound a
bso
rpti
on c
oef
fici
ent
(α)
Frequency (Hz)
PA 4 PC 4
171
(c) Thickness = 200 mm
Figure 5.11 Comparison of pervious concrete and porous asphalt by thickness
in Test Series C (Cont’d)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound a
bso
rpti
on c
oef
fici
ent
(α)
Frequency (Hz)
PA 6 PC 6
172
(a) Pervious concrete
(b) Porous Asphalt
Figure 5.12 Sound absorption coefficient values for pervious concrete and
porous asphalt at varying clogging percentages in Test Series D
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
PC 0% clogged
PC 25% clogged
PC 50% clogged
PC 75% clogged
PC 100% clogged
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Sound A
bso
rpti
on C
oef
fici
ent
(α)
Frequency (Hz)
PA 0% cloggedPA 25% cloggedPA 50% cloggedPA 75% cloggedPA 100% clogged
173
(a) Sound pressure levels of different road materials in Test Series A
b) Overall sound pressure levels of different road materials in Test Series A
Figure 5.13 (a) Sound pressure levels dB(A) at 1/3 octave frequencies and (b)
overall sound pressure levels dB(A) for different road
materials in Test Series A
0
10
20
30
40
50
60
70
80
90
100
110
100 125 160 200 250 315 400 500 630 800 1000125016002000
Sound L
evel
dB
(A)
1/3 Octave Band Centre Frequency (Hz)
PC PF NC NF LC NA OG PA
0
10
20
30
40
50
60
70
80
90
100
110
PC PF NC NF LC NA OG PA
Over
all
Sound L
evel
dB
(A)
Different Road Materials
174
(a) Sound pressure levels for pervious concrete of different porosities
in Test Series B
(b) Sound pressure levels for porous asphalt of different porosities in
Test Series B
Figure 5.14 Sound pressure levels dB(A) at 1/3 octave frequencies for (a)
pervious concrete (b) porous asphalt and (c) overall sound pressure
levels dB(A) for pervious concrete (PC) and porous asphalt (PA)
of varying porosity
0
10
20
30
40
50
60
70
80
90
100
Sound L
evel
dB
(A)
1/3 Octave Band Centre Frequency (Hz)
PC10 PC15 PC20 PC25
0
10
20
30
40
50
60
70
80
90
100
Sound L
evel
dB
(A)
1/3 Octave Band Centre Frequency (Hz)
PA10 PA15 PA20 PA25
175
(c) Overall sound pressure levels of pervious concrete and porous
asphalt of different porosities in Test Series B
Figure 5.14 Sound pressure levels dB(A) at 1/3 octave frequencies for (a)
pervious concrete (b) porous asphalt and (c) overall sound pressure
levels dB(A) for pervious concrete (PC) and porous asphalt (PA)
of varying porosity (Cont’d)
90.0
91.0
92.0
93.0
94.0
95.0
96.0
97.0
PC10 PC15 PC20 PC25 PA10 PA15 PA20 PA25
Over
all
Sou
nd
Lev
el d
B(A
)
Porosity
176
(a) Sound pressure levels for pervious concrete and porous asphalt
materials of different thicknesses in Test Series C
(b) Sound pressure levels for pervious concrete and porous asphalt
materials of different thicknesses in Test Series C
Figure 5.15 (a) Sound pressure levels dB(A) at 1/3 octave frequencies and (b)
overall sound pressure levels dB(A) for pervious concrete (PC)
and porous asphalt (PA) of varying thickness in Test Series C
0
10
20
30
40
50
60
70
80
90
100
Sound L
evel
dB
(A)
1/3 Octave Band Centre Frequency (Hz)
PC PC 4 PC 6 PA PA 4 PA 6
90.0
91.0
92.0
93.0
94.0
95.0
96.0
97.0
PC PC 4 PC 6 PA PA 4 PA 6
Over
all
Sou
nd
Lev
el d
B(A
)
Thickness
177
(a) Sound pressure levels for pervious concrete of different degrees of
clogging in Test Series D
(b) Sound pressure levels for porous asphalt of different degrees of
clogging in Test Series D
Figure 5.16 Sound pressure levels dB(A) at 1/3 octave frequencies for (a)
pervious concrete (b) porous asphalt and (c) overall sound
pressure levels dB(A) for pervious concrete (PC) and porous
asphalt (PA) of varying clogging percentage in Test Series D
0
10
20
30
40
50
60
70
80
90
100
Sound L
evel
dB
(A)
1/3 Octave Band Centre Frequency (Hz)
PC0% PC25% PC50% PC75% PC100%
0
10
20
30
40
50
60
70
80
90
100
Sound L
evel
dB
(A)
1/3 Octave Band Centre Frequency (Hz)
PA0% PA25% PA50% PA75% PA100%
178
(c) Overall sound pressure levels for pervious concrete and porous asphalt
of different clogging percentages in Test Series D
Figure 5.16 Sound pressure levels dB(A) at 1/3 octave frequencies for (a)
pervious concrete (b) porous asphalt and (c) overall sound
pressure levels dB(A) for pervious concrete (PC) and porous
asphalt (PA) of varying clogging percentage Test Series D
(Cont’d)
90
91
92
93
94
95
96
97
98
PC
0%
PC
25%
PC
50%
PC
75%
PC
100%
PA
0%
PA
25%
PA
50%
PA
75%
PA
100%
Over
all
Sound L
evel
dB
(A)
Clogging Percentage
179
CHAPTER 6 CONCLUSION
6.1 Review of work done
In this study, the physical and mechanical properties, clogging and
sound absorption characteristics of pervious concrete with and without steel
fibers were investigated. Tests were carried out to examine the effect of
cement content, coarse aggregate size, water-cement ratio and fiber content on
the compressive and flexural strength as well as the porosity and permeability
of pervious concrete. A steel fiber-reinforced pervious concrete mix was
established, giving the desired flexural strength, permeability and porosity for
use in urban road liable to flash flooding. The clogging effects of residual soils
in pervious concrete were also studied and compared to those in porous
asphalt. In addition, the sound absorption characteristics of pervious concrete
was determined experimentally and compared to other pavement materials
including porous asphalt.
6.2 Summary of main findings
From the studies carried out on pervious concrete, the following conclusions
can be drawn:
6.2.1 Physical and mechanical properties of pervious concrete
(a) To achieve a highly permeable and porous pavement with reasonable
compressive and flexural strengths, the CA/C ratio is recommended to
be in the region of 4.0, water-cement ratio of around 0.3 to 0.35 and
cement in the range of 360 kg/m3 to 400 kg/m
3. Mixes with smaller
coarse aggregates performed marginally better than mixes with larger
180
coarse aggregates due to the regular and more even arrangement of the
aggregates in the concrete matrix.
(b) Steel fibers aid in increasing the compressive and flexural strengths of
pervious concrete. The hook end configuration of the steel fibers did
not lead to significant differences in permeability and porosity of
pervious concrete.
(c) A minimum dosage of 1.5% steel fiber per volume of concrete is
recommended to achieve the target flexural strength of 3.5 MPa,
permeability of 10 mm/s and porosity of 20%.
6.2.2 Clogging characteristics of pervious concrete
(a) The permeability and clogging resistance of pervious concrete
increased substantially when the mixture porosity was more than 20%.
Pervious concrete specimens gave higher initial permeability than the
porous asphalt specimens with the same porosity.
(b) Pervious concrete was less susceptible to clogging compared to porous
asphalt with the same porosity, and the incorporation of steel fibers up
to about 2% did not affect the results.
6.2.3 Sound absorption capacity of pervious concrete
(a) Pervious concrete performed comparatively better than porous asphalt,
open-graded asphalt, dense asphalt, normal weight concrete and lean
concrete. The use of steel fibers in pervious concrete and normal
weight concrete did not affect their sound absorption capacity
significantly.
181
(b) An increase in porous specimen porosity and thickness did not
significantly aid in improving sound absorption capacity.
(c) Even with increased clogging, the sound absorption capacity of
pervious concrete was not significantly compromised.
(d) Based on the overall sound pressure level, pervious concrete with or
without steel fibers were comparable in performance and these mixes
achieved a significant overall sound pressure reduction of more than
4.5 dB(A) when compared to normal weight concrete and dense graded
asphalt mixes.
6.3 Recommendations for further research
Further work may be carried out in the following areas.
1. The test results obtained in this study could be calibrated with actual
pervious concrete road site construction and field testing.
2. Fatigue testing of pervious concrete slabs incorporating wet and dry
cycles can be done to mimic actual road conditions.
3. With a view in the reduction of urban heat island effect (ACI
Committee Report 522, 2010), thermal conductivity test can be carried
out on pervious concrete.
4. A possible problem with the use of steel fibers in pervious concrete is
the corrosion of the steel fibers which would then affect the long
performance of the pervious concrete. A study on the effect of
corrosion of steel fibers in pervious concrete can be carried out.
182
5. With the prospect that repeated traffic loadings may cause wear and
polishing of the pervious concrete surface, the Los Angeles Abrasion
test can be carried out.
183
LIST OF PUBLICATIONS
Journals:
1. T. F. Fwa, Lim E. and K. H. Tan. (2015). Comparison of Permeability
and Clogging Characteristics of Porous Asphalt and Pervious
Concrete Pavement Materials, Journal of the Transportation Research
Board (TRB), No. 2511, pp 72-80.
2. Lim, E., Tan, K.H and Fwa, T.F. (2013). Effect of Mix Proportion on
Strength and Permeability of Pervious Concrete for Use in Pavement,
EASTS/ ATS Journal, Volume 10, pp. 1565-1575.
3. Lim, E., Tan, K.H and Fwa, T.F. (2013). High-strength high-porosity
pervious concrete pavement, Advanced Material Research Journal,
Vol. 723, pp. 361-367.
Conferences:
1. Tan, K.H, Lim, E and Fwa, T.F. (2015). Steel fiber-reinforced pervious
concrete for urban roads, USMCA 14th
International Symposium on
New Technology for Urban Safety of Mega Cities in Asia, October 29
– 31, Kathmandu, Nepal.
2. Lim, E., Tan, K.H and Fwa, T.F. (2015). Laboratory Evaluation of
Clogging Behavior of Pervious Concrete Pavements, EASTS Eastern
Asia Society for Transportation Studies Conference, September 11 -
14, Cebu, Philippines.
3. Lim, E., Tan, K.H and Fwa, T.F. (2015). Laboratory Evaluation of
Clogging Behavior of Porous Asphalt Pavement, 6th International
conference bituminous mixtures and pavements, June 10 - 12,
Thessaloniki, Greece.
184
4. Lim, E., Tan, K.H and Fwa, T.F. (2013). Effect of Mix Proportion on
Strength and Permeability of Pervious Concrete for Use in Pavement,
EASTS Eastern Asia Society for Transportation Studies Conference,
September 9 – 12, Taiwan Taipei.
5. Lim, E., Tan, K.H and Fwa, T.F. (2013). High-strength high-porosity
pervious concrete pavement, 8th ICPT International Committee on
Road and Airfield Pavement Technology Conference, 14 – 18 July,
Taiwan, Taipei.
6. Lim, E., Tan, K.H and Fwa, T.F. (2013). Pervious concrete pavement
mix design, 18th Singapore Symposium on Pavement Technology
Conference (SPT), 31 May, National University of Singapore.
185
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211
ANNEX A: Residual Normality Analysis
Assumptions for regression model:
Fitting a regression model requires several assumptions. Estimation of
the model parameters requires assumption that the errors are uncorrelated
random variables with mean zero and constant variance. Test of hypotheses
and interval estimation require that the errors be normally distributed. In
addition, it is assumed that the order of the model is correct, that is if a simple
linear regression model is fitted, it is assumed that the phenomenon usually
behaves in a linear or first-order manner. The residuals from the regression
model are defined as ei = yi – yn, i = 1,2,…,n (Montgomery et al., 2011 and
2006).
The residuals for the equations shown below are normally distributed
as the P-value were more than 0.05 using the Anderson-Darling Normality
Test as shown in Figures A.9 to A.16 below.
For pervious concrete with:
10% Porosity: k = 2.453e-0.338N
R2 = 0.996 (4.7)
15% Porosity: k = 13.019e-0.271N
R2 = 0.948 (4.8)
20% Porosity: k = 15.790e-0.304N
R2 = 0.989 (4.9)
25% Porosity: k = 17.117e-0.062N
R2 = 0.952 (4.10)
For porous asphalt with:
10% Porosity: k = 2.127e-0.291N
R2 = 0.992 (4.11)
15% Porosity: k = 4.927e-0.416N
R2 = 0.978 (4.12)
20% Porosity: k = 7.668e-0.290N
R2 = 0.992 (4.13)
25% Porosity: k = 15.272e-0.211N
R2 = 0.992 (4.14)
212
Regression method:
k = a1eb1N
(A.1)
ln(k) = ln(a) + b1(N) (A.2)
Figure A.1 Porous Asphalt 10%
Figure A.2 Porous Asphalt 15%
y = -0.2904x + 0.1628
R² = 0.9919
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
)
Clogging Cycle
Porous Asphalt 10%
y = -0.4109x + 0.9707
R² = 0.9738
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
)
Clogging Cycle
Porous Asphalt 15%
213
Figure A.3 Porous Asphalt 20%
Figure A.4 Porous Asphalt 25%
y = -0.293x + 1.4759
R² = 0.9909
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
)
Clogging Cycle
Porous Asphalt 20%
y = -0.2128x + 2.1971
R² = 0.9885
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
)
Clogging Cycle
Porous Asphalt 25%
214
Figure A.5 Pervious Concrete 10%
Figure A.6 Pervious Concrete 15%
y = -0.3382x + 0.3143
R² = 0.996
-5.5
-5.0
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
) Clogging Cycle
Pervious Concrete 10%
y = -0.2704x + 1.9552
R² = 0.9491
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
)
Clogging Cycle
Pervious Concrete 15%
215
Figure A.7 Pervious Concrete 20%
Figure A.8 Pervious Concrete 25%
y = -0.3109x + 2.2825
R² = 0.9805
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
)
Clogging Cycle
Pervious Concrete 20%
y = -0.0839x + 2.5085
R² = 0.9668
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity l
n k
(m
m/s
)
Clogging Cycle
Pervious Concrete 25%
216
Normality Plots
Figure A.9 Porous Asphalt 10% residuals
The normality assumption is acceptable as the residuals plot for PA10 show
that they are normally distributed since they have a p-value of 0.868 which is
greater than 0.05.
Figure A.10 Porous Asphalt 15% residuals
The normality assumption is acceptable as the residuals plot for PA15 show
that they are normally distributed since they have a p-value of 0.884 which is
greater than 0.05.
217
Figure A.11 Porous Asphalt 20% residuals
The normality assumption is acceptable as the residuals plot for PA20 show
that they are normally distributed since they have a p-value of 0.250 which is
greater than 0.05.
Figure A.12 Porous Asphalt 25% residuals
The normality assumption is acceptable as the residuals plot for PA25 show
that they are normally distributed since they have a p-value of 0.333 which is
greater than 0.05.
218
Figure A.13 Pervious Concrete 10% residuals
The normality assumption is acceptable as the residuals plot for PC10 show
that they are normally distributed since they have a p-value of 0.429 which is
greater than 0.05.
Figure A.14 Pervious Concrete 15% residuals
The normality assumption is acceptable as the residuals plot for PC15 show
that they are normally distributed since they have a p-value of 0.252 which is
greater than 0.05.
219
Figure A.15 Pervious Concrete 20% residuals
The normality assumption is acceptable as the residuals plot for PC20 show
that they are normally distributed since they have a p-value of 0.913 which is
greater than 0.05.
Figure A.16 Pervious Concrete 25% residuals
The normality assumption is acceptable as the residuals plot for PC25 show
that they are normally distributed since they have a p-value of 0.394 which is
greater than 0.05.
220
ANNEX B: Statistical analysis using T-Test: Two samples assuming
unequal variances for selected mixes
Assumptions for two-sample inference:
i. X11, X12,…, 𝑋1𝑛1, is a random sample from population 1.
ii. X21, X22,…, 𝑋2𝑛2, is a random sample from population 2.
iii. The two populations represented by X1 and X2 are independent.
iv. Both populations are normal.
B-1) Statistical analysis using T-Test: Two samples assuming unequal
variances for permeability deterioration of pervious concrete and porous
asphalt
Figure 4.5 Comparison of permeability deterioration curves of porous asphalt
and pervious concrete mixtures
0123456789
101112131415161718192021222324252627
0 1 2 3 4 5 6 7 8 9 10
Per
mea
bil
ity C
oef
fici
ent,
k (
mm
/s)
Clogging Cycle
PA 10% PA 15%PA 20% PA 25%PC 10% PC 15%PC 20% PC 25%
Legend:
PA = Porous Asphalt
PC = Pervious Concrete
Numerical values indicate
PC 25%
PC 20%
PA 25%
PC 15%
PA 20% PA 15%
PC 10%
PA 10%
221
Hypothesis Testing Statement
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses:
𝐻𝑎: 𝜇1 ≠ 𝜇2 , or
𝐻𝑎: 𝜇1 < 𝜇2 , or
𝐻𝑎: 𝜇1 > 𝜇2
Table B.1 details the p-values and conclusions drawn from the
hypothesis testing.
Based on the T-test: Two-samples assuming unequal variances test,
most of the results from the comparison of permeability deterioration of
porous asphalt and pervious concrete mixtures could be accepted at the 95%
confidence level as most of their p-values were less than 0.05. The null
hypothesis was rejected in favor of the alternative hypothesis as shown in
Table B-1.
Some of the porous mixture combinations have p-values more than
0.05 and these were highlighted in bold. As their p-value was greater than
0.05, therefore the results were not statistically significant at the 95%
significance level. The null hypothesis was not rejected and the results were
not statistically different.
222
Table B.1. P-values and conclusions for the comparison of permeability
deterioration (mm/s) of porous asphalt and pervious concrete mixtures from
the T-test: Two samples assuming unequal variances
Cycle 0 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.001623
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.003556
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.000033
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.414961
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA15 0.132539
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.006180
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.006000
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
223
Cycle 0 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.004808
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.000084
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.003991
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.004643
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.049362
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.041662
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
224
Cycle 0 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.003548
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.000013
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.000172
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.000539
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.268559
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25
PA10 0.000825
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.000129
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.000218
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.013122
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
225
Cycle 0 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.037896
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.002519
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.013136
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.001405
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.017696
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.038628
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 PA25 - -
226
Cycle 1 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.003219
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.001204
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.000197
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.284609
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA15 0.316823
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.012264
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.001574
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
227
Cycle 1 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.015597
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.001053
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.006154
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.009056
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.049487
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.041662
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
228
Cycle 1 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.016123
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.000640
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.000087
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.000334
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.341377
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25
PA10 0.002246
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.002636
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.001132
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.015004
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
229
Cycle 1 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.002819
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.004315
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.007154
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.002186
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.009025
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.024622
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 PA25 - -
230
Cycle 2 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.003077
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.004180
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.003538
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.259230
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA15 0.242377
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.005414
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.000489
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
231
Cycle 2 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.086140
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25 0.018951
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.009798
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.013208
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.106163
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.047964
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
232
Cycle 2
/Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.049791
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA10 0.000074
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.000002
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.001554
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA25 0.264994
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PC25
PA10 0.009249
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.010758
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.021876
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA25 0.063552
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
233
Cycle 2 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.018240
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.018240
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.000560
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.000918
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.003647
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.006740
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 PA25 - -
234
Cycle 3 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.004023
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.001268
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.003958
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.311942
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA15 0.267060
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.005840
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.006038
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
235
Cycle 3 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.227923
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25 0.019913
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.011146
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.015424
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.149764
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.160627
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
236
Cycle 3 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.043097
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.004779
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.006359
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.034033
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.314613
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25
PA10 0.010057
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.011557
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.023952
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.040277
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
237
Cycle 3 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.001941
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.003291
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.010628
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.005083
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.013664
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.068790
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 PA25 - -
238
Cycle 4 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.021615
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.009774
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.004446
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.030685
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.231346
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.003938
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.011864
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
239
Cycle 4 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.451347
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different..
PC25 0.004245
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.018073
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.023879
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.258056
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.221953
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
240
Cycle 4
/Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.006204
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA10 0.008071
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.011112
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.141870
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PA25 0.215991
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different..
PC25
PA10 0.004107
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.004677
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.010216
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA25 0.006663
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
241
Cycle 4 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.043281
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.002901
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.010180
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.001179
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.013010
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.066933
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 PA25 - -
242
Cycle 5 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.001542
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.009964
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.008194
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.005257
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.005746
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.012439
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.005850
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
243
Cycle 5 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.212083
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25 0.013096
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.000038
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.000084
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.224685
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.278253
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
244
Cycle 5
/Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.008194
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA10 0.008872
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.011029
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.131029
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PA25 0.494903
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PC25
PA10 0.005257
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.005688
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.012439
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA25 0.005850
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
245
Cycle 5 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.213213
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.000597
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.017261
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.001010
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.021076
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.212490
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 PA25 - -
246
Cycle 6 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.025175
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.000142
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.007950
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.032656
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.356435
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.025103
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.000931
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
247
Cycle 6 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.110971
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25 0.005375
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.015905
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.024898
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.423702
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.058304
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
248
Cycle 6
/Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.016329
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA10 0.000254
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.000397
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.075916
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PA25 0.142466
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PC25
PA10 0.007110
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.007964
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.004981
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA25 0.018997
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
249
Cycle 6 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.003658
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.015343
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.002893
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.024668
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.003854
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.041582
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 PA25 - -
250
Cycle 7 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.039111
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.000293
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.008386
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.031325
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.341138
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.033985
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.029696
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
251
Cycle 7 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.092526
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25 0.005439
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.029720
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.040290
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.456072
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.170563
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
252
Cycle 7 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.017388
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.000233
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.001905
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.047990
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.420865
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25
PA10 0.007890
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.008438
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.005014
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.009106
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
253
Cycle 7 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.021020
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.025433
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.024568
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.034979
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.030322
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.153763
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 PA25 - -
254
Cycle 8 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.049653
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.001594
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.006703
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.043992
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.361687
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.059300
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.014387
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
255
Cycle 8 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.008723
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.009418
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.043416
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.051173
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.437635
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.029984
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
256
Cycle 8 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.014457
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.001519
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.001646
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.008095
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.220488
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25
PA10 0.006583
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.006729
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.009266
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.005231
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
257
Cycle 8 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.043685
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.051466
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.013508
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.061186
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.014607
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.026224
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 PA25 - -
258
Cycle 9 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.020689
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.004789
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.008332
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.041989
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.198869
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.017322
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.023049
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
259
Cycle 9 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.018178
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.010940
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.019348
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.021445
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.449983
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.068258
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
260
Cycle 9 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.013681
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.004603
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.004893
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.028799
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.403573
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25
PA10 0.008265
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.008366
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.011240
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.005981
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
261
Cycle 9 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.024383
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.021571
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.022297
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.023719
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.023452
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.082314
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 PA25 - -
262
Cycle 10 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC10
PC15 0.026341
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC20 0.010850
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PC25 0.009765
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.094921
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher permeability than PA10.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA15 0.163082
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA15.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.002353
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.013319
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
263
Cycle 10 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC15
PC20 0.165886
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25 0.012218
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA10 0.024982
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.027135
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.463185
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.092085
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
264
Cycle 10
/Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PC20
PC25 0.013046
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PC25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA10 0.010418
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.011096
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.111092
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher permeability than PA20.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PA25 0.268199
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the results
are not statistically significant at the 95% significance
level. The null hypothesis is not rejected and the results
are not statistically different.
PC25
PA10 0.009710
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA10.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA15 0.009795
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA15.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA20 0.011868
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA20.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
PA25 0.013862
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC25 has higher permeability than PA25.
As the p-value was less than 0.05, the null hypothesis is
rejected in favor of the alternative hypothesis.
265
Cycle 10 /Clogged
permeability
Mix
T-test
Two
samples
assuming
unequal
variances
(p-value)
Conclusion [Permeability (mm/s)]
PA10
PA15 0.036190
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA15.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 0.002251
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.012860
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA10 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15
PA20 0.002399
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA20.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA25 0.013581
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA15 has lower permeability than PA25.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA20 PA25 0.079196
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PA20 has lower permeability than PA25.
As the p-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 PA25 - -
266
B-2) Statistical analysis using T-Test: Two samples assuming unequal
variances for Sound Pressure Level dB(A) for Series B – Porosity
Figure 5.14 Overall sound pressure levels of pervious concrete and porous
asphalt of different porosities in Series B.
Based on the T-test: Two-samples assuming unequal variances test, not
all the results from Series B could be accepted at the 95% confidence level as
most of their P-values were more than 0.05. Therefore there was not sufficient
evidence to reject the null hypothesis and the results were not statistically
different.
The results between PC25 and PA10 accepted at the 95% confidence
level as their p-values were less than 0.05. The null hypothesis was rejected in
favor of the alternative hypothesis. Table B.2 detailed the p-values and
conclusions drawn from the hypothesis testing.
90.0
91.0
92.0
93.0
94.0
95.0
96.0
97.0
PC10 PC15 PC20 PC25 PA10 PA15 PA20 PA25
Over
all
Sou
nd
Lev
el d
B(A
)
Porosity
267
Table B.2. P-values and conclusions for the overall sound pressure level
dB(A) from the T-test Two samples assuming unequal variances for Series B
Series B Mix
T-test: Two-
samples
assuming
unequal
variances
(p-value)
Conclusion [Overall sound level dB(A)]
PC10
96.2 dB(A)
PC15 0.178
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher dB(A) than PC15.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC20 0.130
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher dB(A) than PC20
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PC25 0.096
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher dB(A) than PC25
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA10 0.178
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower dB(A) than PA10.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA15 0.274
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC10 has lower dB(A) than PA15.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.500
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 ≠ 𝜇2
No difference in dB(A).
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.274
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC10 has higher dB(A) than PA25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
268
Series B Mix
T-test:
Two-
samples
assuming
unequal
variances
(p-value)
Conclusion [Overall sound level dB(A)]
PC15
96.0
dB(A)
PC20 0.500
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 ≠ 𝜇2, i.e.
No difference in dB(A).
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PC25 0.241
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has higher dB(A) than PC25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA10 0.069
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC15 has lower dB(A) than PA10
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA15 0.099
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower dB(A) than PA15.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA20 0.178
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower dB(A) than PA20.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA25 0.311
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC15 has lower dB(A) than PA25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
269
Series B Mix
T-test:
Two-
samples
assuming
unequal
variances
(p-value)
Conclusion [Overall sound level dB(A)]
PC20
96.0
dB(A)
PC25 0.225
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC20 has higher dB(A) than PC25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA10 0.058
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower dB(A) than PA10.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA15 0.051
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower dB(A) than PA15.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA20 0.130
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower dB(A) than PA20.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA25 0.259
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC20 has lower dB(A) than PA25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
270
Series B Mix
T-test: Two-
samples
assuming
unequal
variances
(p-value)
Conclusion [Overall sound level dB(A)]
PC25
95.8 dB(A)
PA10 0.040
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC25 has lower dB(A) than PA10.
As the p-value was less than 0.05, the null hypothesis
is rejected in favor of the alternative hypothesis.
PA15 0.060
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC25 has lower dB(A) than PA15.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.096
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC25 has lower dB(A) than PA20.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.142
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC25 has lower dB(A) than PA25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA10
96.4 dB(A)
PA15 0.311
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA10 has higher dB(A) than PA15.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA20 0.178
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA10 has higher dB(A) than PA20.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
PA25 0.099
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA10 has higher dB(A) than PA25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not rejected
and the results are not statistically different.
271
Series B Mix
T-test:
Two-
samples
assuming
unequal
variances
(p-value)
Conclusion [Overall sound level dB(A)]
PA15
96.3
dB(A)
PA20 0.274
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA15 has higher dB(A) than PA20.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA25 0.115
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA15 has higher dB(A) than PA25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA20
96.2
dB(A)
PA25
0.274
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA20 has higher dB(A) than PA25.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA25
96.1
dB(A)
PA25
-
-
272
B-3) Statistical analysis using T-Test: Two samples assuming unequal
variances for Sound Pressure Level dB(A) for Series C – Thickness
Figure 5.15 Sound pressure levels for pervious concrete and porous asphalt
materials of different thicknesses in Series C.
Based on the T-test: Two-samples assuming unequal variances test, not
all the results from Series C could be accepted at the 95% confidence level as
most of their P-values were more than 0.05. Therefore there is not sufficient
evidence to reject the null hypothesis and the results were not statistically
different. The results between PC6 and PA as well as PC6 and PA4 can be
accepted at the 95% confidence level as their P-values were less than 0.05.
The null hypothesis was rejected in favor of the alternative hypothesis. Table
B.3 detailed the p-values and conclusions drawn from the hypothesis testing.
90.0
91.0
92.0
93.0
94.0
95.0
96.0
97.0
PC PC 4 PC 6 PA PA 4 PA 6
Over
all
Sou
nd
Lev
el d
B(A
)
Thickness
273
Table B.3. P-values and conclusions for the overall sound pressure level
dB(A) from the T-test Two samples assuming unequal variances for Series C
Series C Mix
T-test Two
samples
assuming
unequal
variances
(p-value)
Conclusions [Overall sound level dB(A)]
PC
96.1
dB(A)
PC4 0.500
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 ≠ 𝜇2, i.e.
No difference in dB(A).
As the P-value is greater than 0.05, therefore
the results are not statistically significant at the
95% significance level. The null hypothesis is
not rejected and the results are not statistically
different.
PC6 0.225
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC has higher dB(A) than PC6.
As the P-value is greater than 0.05, therefore
the results are not statistically significant at the
95% significance level. The null hypothesis is
not rejected and the results are not statistically
different.
PA 0.061
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC has lower dB(A) than PA.
As the P-value is greater than 0.05, therefore
the results are not statistically significant at the
95% significance level. The null hypothesis is
not rejected and the results are not statistically
different.
PA4 0.115
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC has lower dB(A) than PA4.
As the P-value is greater than 0.05, therefore
the results are not statistically significant at the
95% significance level. The null hypothesis is
not rejected and the results are not statistically
different.
PA6 0.274
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC has lower dB(A) than PA6.
As the P-value is greater than 0.05, therefore
the results are not statistically significant at the
95% significance level. The null hypothesis is
not rejected and the results are not statistically
different.
274
Series C
Mix
T-test Two
samples
assuming
unequal
variances
(p-value)
Conclusions [Overall sound level dB(A)]
PC4
96.1 dB(A)
PC6 0.144
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PC4 has higher dB(A) than PC6.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA 0.051
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC4 has lower dB(A) than PA.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA4 0.091
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC4 has lower dB(A) than PA4.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PA6 0.248
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC4 has lower dB(A) than PA6.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
PC6
96.0 dB(A)
PA 0.027
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC6 has lower dB(A) than PA.
As the p-value was less than 0.05, the null
hypothesis is rejected in favor of the alternative
hypothesis.
PA4 0.040
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC6 has lower dB(A) than PA4.
As the p-value was less than 0.05, the null
hypothesis is rejected in favor of the alternative
hypothesis.
PA6 0.110
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 < 𝜇2, i.e.
PC6 has lower dB(A) than PA6.
As the P-value is greater than 0.05, therefore the
results are not statistically significant at the 95%
significance level. The null hypothesis is not
rejected and the results are not statistically
different.
275
Series C Mix
T-test Two
samples
assuming
unequal
variances
(p-value)
Conclusions [Overall sound level dB(A)]
PA
96.4
dB(A)
PA4 0.274
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA has higher dB(A) than PA4.
As the P-value is greater than 0.05, therefore
the results are not statistically significant at
the 95% significance level. The null
hypothesis is not rejected and the results are
not statistically different.
PA6 0.144
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA has higher dB(A) than PA6.
As the P-value is greater than 0.05, therefore
the results are not statistically significant at
the 95% significance level. The null
hypothesis is not rejected and the results are
not statistically different.
PA4
96.3
dB(A)
PA6
0.274
Null hypothesis: 𝐻0: 𝜇1 = 𝜇2
Alternative hypotheses: 𝐻𝑎: 𝜇1 > 𝜇2, i.e.
PA4 has higher dB(A) than PA6.
As the P-value is greater than 0.05, therefore
the results are not statistically significant at
the 95% significance level. The null
hypothesis is not rejected and the results are
not statistically different.
PA6
96.2
dB(A)
PA6
-
-
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