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JOURNAL OF RESOURCE
MANAGEMENT AND TECHNOLOGY
ISSN NO: 0745-6999
Vol12, Issue4, 2021
Page No:170
INVESTIGATION OF PERMEABILITY PROPERTIES OF FIBER REINFORCED
POROUS CONCRETE USED IN RIGID PAVEMENTS 1Sirivella. Hareesh, 2Siva Naga Raju Arepalli,3C.Venkata Ramireddy
1M.Tech Student, 23Assistant Professor
Dept Of Civil Engineering
SVR Engineering College, NANDYAL ABSTRACT
Degradation of Concrete by the acid attack, the occurrence of reinforcement corrosion and associated damage of Concrete
because of water intrusion is progressively being recognized as some of the threatening Durability problems in Reinforced Concrete
Structures. High Performance Concrete is a novel construction material with improved properties like Higher Strength, Durability,
Higher Constructability, etc. In the present investigation an exertion has been made to inquire about the joint impact of addition of
silica fume and Steel Fibers on the Durability of SFR-HPC with regard to Impermeability of Concrete. A HPC of M40 grade was
considered and Permeability test were performed to find the persistence of Steel Fiber Reinforced High Performance Concrete. The
main variables considered in this study are. Four various proportions of Micro Silica viz. 0%, 5%, 7.5%, 10% by weight of Cement.
Three different Aspect Ratios of Steel Fibers i.e. 60, 70, 80. Three different Volume Fractions of Fibers i.e. 0.5%, 0.75%, 1.0%.
A total of 39 numbers of Concrete specimens were cast with and without Micro Silica and Steel Fibers and tested as per
IS: 3085 specification for Permeability. An average of 3 specimens was taken for each mix and Coefficient of Permeability was
determined. Test results indicate that by adding of Micro-Silica to Plain Concrete up to 10% decreases its Permeability by about
52%.Further, addition of Micro Silica 5% and Steel Fibers fraction of 1.0%, reduces its Coefficient of Permeability from 10.48×10-
5 centimeter/second to 3.69×10-5 centimeter/second. The reduction is about 35%. It is also noted that addition of 7.5% Micro Silica
and Steel Fibers above 0.75% fraction, results indicate in increase in Coefficient of Permeability value. Further experimental results
reveals that addition of 10% Micro Silica along with Steel Fibers do not reduce the value of Coefficient of Permeability of Concrete.
In all, the results of present investigation gave an insight on possible way of improving impermeability of Concrete by
making use of mineral admixtures like Micro Silica in combination with Steel Fibers.
I.INTRODUCTION
Concrete production exists around the world as a leading material in construction for our infrastructure and essentially today,
this man-made stone has risen as a most versatile and universally recognized tool to build with. The durability of concrete is
characterized as the capacity of the material to stay workable for in any event the required lifetime of the structure. Likewise, its
durability is fundamental in safeguarding the infrastructure of society. Amongst the different strategies to improve the Durability of
Concrete, and to accomplish High Performance Concrete, the utilization of Micro Silica is a newly approach.
In many situations, the durability of concrete is likewise legitimately identifies with its permeability which again depends a
great deal upon its protection from entrance of dampness. The dampness which goes into the concrete can prompt to disintegration
of steel reinforcement and diminishes the life of the structures radically. Accordingly, the durability of concrete depends to great
extent upon the penetrability of concrete which is characterized as the simplicity with which it enables the liquids to go through it.
Moreover, it is by reducing the permeability, the time is known to be extended so as to prevent any aggressive chemical to get into
the concrete where it can do its damage. Consequently, a significant proportion of improving concrete impermeability is to initially
improve the capacity of opposing shrinkage and arresting crack.
In the past, several examination have demonstrated that addition of Mineral Admixtures and fiber steel is an proficient
technique to improve the mechanical performance of weak networks as mortars and concretes by preventing cracking. Additionally,
it is very much popular to increase fracture durability given by fiber spanning on the primary crack plane prior to crack augmentation.
Debonding, sliding and hauling-out of the filaments have been featured as the nearby systems that control the bridging action.
Figure.1: Porous concrete
Rigid Pavement:
JOURNAL OF RESOURCE
MANAGEMENT AND TECHNOLOGY
ISSN NO: 0745-6999
Vol12, Issue4, 2021
Page No:171
Rigid pavements have sufficient flexural strength to transmit the wheel load stresses to a wider area below. Compared to flexible
pavement, rigid pavements are placed either directly on the prepared sub-grade or on a single layer of granular or stabilized material.
Since there is only one layer of material between the concrete and the sub-grade, this layer can be called as base or sub-base course
in rigid pavement, load is distributed by the slab action, and the pavement behaves like an elastic plate resting on viscous medium
Rigid pavements are constructed by Portland cement concrete (PCC) and should be analysed by plate theory instead of layer theory,
assuming an elastic plate resting on viscous foundation.
Figure: Cross section of Rigid Pavement
1.1 PERMEABILITY OF CONCRETE
Permeability, described as moment of liquid through a porous medium under an application of pressure head, is the most
significant property of concrete administrating its long-term strength. Permeability of concrete, thus, is affected by two essential
components: inter-connected porosity in cement paste and thinline cracks in the concrete. Porosity in the paste of cement and the
level of its interconnectivity are ov
erseen for most of the part by water-cementatious (w/c) ratio, level of compaction and level of hydration. Density and Area of
interfacial micro cracks, then again, are controlled by level of connected pressure of distortion, outside or inside, experienced by the
concrete.
Most Analysts accept that a charmingly and produced concrete is initially water-tight, having irregular pores and miniaturized
cracks. By then, when presented to over outrageous loading or weathering, concrete debilitates through a variety of physical and
compound processes, which brings about breaking. Cracks in concrete for most part interconnect stream ways and increment
concrete penetrability. The expansion in concrete penetrability because of split movements allows more water or forceful compound
particles to penetrate into the concrete, facilitating further decaying. Such a chain reaction of “disintegration-cracking-progressively-
penetrable-concrete-further decaying” in the endresult in quinoas decay of the concrete structure.
1.2 HIGH PERFORMANCE CONCRTE
Over the past two decades, High performance concrete (HPC) has been widely used in the field by the contractors. Even
in marine construction engineering, the proportion of concrete was often characterized by low water-binder ratio, adequate mineral
admixtures and super plasticizers to attain low chloride permeability and high frost resistance.
American Concrete Institute (ACI) characterizes HPC as an extraordinarily assemble concrete, at any rate specific qualities
of which have been overhauled through the assurance of segment materials and blend extents. Consider that this definition does not
cover a lone thing yet rather a gathering of innovative solid items whose properties have been exclusively fitted to meet explicit
building needs, for instance, high usefulness, extremely high early quality (for example 30-40 Megapascals compressive quality in
1440 minutes), outrageous sturdiness, and high strength to presentation conditions.
An important investigation against the ACI meaning of HPC is that strength of cement isn't required; it is one of the option.
The distortion that high-quality will normally prompt high-strength has in all probability achieved various cases of breaking and
less than ideal rot of HPC structures. The reason lies in the blend extents used to achieve high-quality; for example, business high-
quality solid blends are much of the time expected to get 50-80Mpa compressive quality at 28-day and on occasion high early-
quality qualities on the request of 25-40Mpa at 1-day, together with 150-200 mm droop for the straightforwardness of
constructability if the structure is seriously strengthened. Generally, these mixes are made out of a high bond content, viz 450-500
kilogram/meter³ Portland or mixed Portland concrete having a reasonably constrained amount of micro silica and fly ash, a low
water/cement proportion (w/c) on the request of 0.3 (with the assistance of a super plasticizing admixture), and an air-entraining
master when it is essential to shield the solid from cycles of solidifying and defrosting..
JOURNAL OF RESOURCE
MANAGEMENT AND TECHNOLOGY
ISSN NO: 0745-6999
Vol12, Issue4, 2021
Page No:172
1.3 SUPPLEMENTARY CEMENTITIOUS MATERIALS
Severe ecological contamination controls and guidelines have prompted an expansion in utilization of industrial wastes
and sub graded by-products like fly ash, silica fume, ground granulated blast furnace slag etc., as supplementary-cementitious
materials (SCMs). The utilization of SCMs in concrete constructions not only counteracts to check the contaminatiom but also to
improve the properties of concrete in fresh and solidified states.
These SCMs can be assigned into two grouping relying upon their sort of react: pressure driven and pozzolanic. Pressure
driven materials reacts really with water to give cementitious compound like GGBS. Pozzolanic materials does not have any
cementitious property yet when used with bond or lime react with (CaOH) to shape items having cementitious properties.
1.3.1 MICRO SILICA
Silica fume, otherwise called as Micro Silica, is an aftereffect of lessening of high-purity quartz alongside coal in electric
furnaces in the making of silicon and ferrosilicon composites. In the past, Micro silica has proven to be an excellent admixture for
Portland cement concrete. Adding of Micro Silica to a concrete mix is said to be resulting in significant improvements in strength,
durability and permeability. Reasonably, improvements to the concrete properties occur because Micro Silica is a pozzolan.
Knowingly, Pozzolans are finely divided Silica that combine with free lime (CaOH) to create more CaH2O4Si. Also, Microsilica is
estimated to be about a hundred times finer than cement, giving it the ability to plug voids between cement particles, and helping it
increase the density of the cement matrix.
1.3.2 POZZOLANIC REACTIVITY
Micro Silica is an ultra fine material that, when added to concrete, physically packs the Voids between Cement particles
resulting in extremely dense and Impermeable Concrete. Micro Silica is Siliceous pozzolans (SiO2) which reacts with weak and
soluble Calcium Hydroxide (CH), a byproduct of Cement hydration process, to form a stable insoluble, Strength adding, Highly
Cementitious Calcium Silicates and dramatically reduce Permeability.
1.4 FIBERS
Plain concrete have lesser elasticity, confined flexibility and little insurance from breaking. Interior micro cracks are
basically present in the solid and its poor Rigidity is a result of to the spread of such micro cracks, at last inciting to Weak Crack of
the concrete. In the past endeavors have been made for the improvement in malleable properties of Cement by using Traditional
Strengthened Steel bars and moreover by applying Limiting strategies. Albeit both these systems give Rigidity to the Solid
individuals, they regardless, don't expand the Inborn Elasticity of solid itself. It has been seen that the expansion of litt le firmly
divided and reliably scattered strands to concrete would go about as split arrester and would improve its static and dynamic
properties. Strands are essentially depicted by one long pivot with other two axes every now and again frequently roundabout or
close round.
1.4.1 FIBER REINFORCEMENT
Fibers are the noteworthy class of reinforcement, as they satisfy the perfect conditions and move solidarity to the system
constituent and improving their properties as needed. Glass filaments are the most prepared acknowledged strands used to fortify
materials. Earth and metal strands were as such found and put to wide use, to render composites stiffer progressively impervious to
vitality of warmth.
Filaments come up short of perfect execution in light of a couple of reasons. The performance of a fiber composite is settled
on choice by its length, shape, and direction, composition of the filaments and the mechanical properties of the network.
The direction of the fiber in the lattice implies that the nature of composite and the quality most noticeable along the
longitudinal directional of fiber. This doesn't mean the longitudinal fibers can take the comparable quantum of weight self-sufficient
of the course in where in it is applied. Perfect execution from longitudinal filaments can be gotten if the heap is associated along its
direction. The littlest move in the edge of stacking may fundamentally lessen the nature of the composite.
1.5 STEEL FIBER REINFORCED CONCRETE
Steel Fiber Reinforced Concrete (SFRC) is a composite material wherein short discrete Steel strands are arbitrarily scattered
all through the concrete mass. Expansive research chip away at SFRC has arrangement that the adding of Steel strands to Plain bond
Concrete (PCC) improves its Ductility, Toughness, Durability, Strength, Post-Cracking Load Resistance, etc. Its utilization has
consistently expanded during the most recent two decades everywhere throughout the world and its present fields of application
includes Highway and Airport Pavements, Explosion Resistant and Earthquake Resistant structures, Tunnel and Mine linings, Rock-
Slope stabilization, Bridge Deck overlay, Hydraulic Structures and so forth.
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ISSN NO: 0745-6999
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Page No:173
1.6 NEED FOR PRESENT STUDY
The durability of concrete depends a great deal upon its protection from entrance of dampness. The dampness which goes
inside the concrete can prompt erosion of steel reinforcement and decrease the life of the structure definitely. Regardless of the way
that, the durability of concrete relies on the porousness of concrete which is portrayed as the straightforwardness with which it
empowers the fluid to experience in it. Despite the fact that the durability is a key factor influencing the life span of concrete
structure, just few examinations were completed to explore the impact of expansion of micro silica on the Durability of Normal and
High Performance Concrete. Utilization of Micro Silica diminishes the Permeability of Concrete. Usage of Steel Fibers increases
the tensile strength present in the structure. A literature survey shows that while so many researchers considered the individual
impact of adding of either Micro Silica or Steel Fibers on Durability of Normal Concrete, very few reports are available on the
influence of presence of both Micro Silica and Steel Fibers on the Permeability of Concrete. Hence an attempt has been made to
consider the joint impact of Micro Silica and Steel Fibers on the Durability of High Performance Concrete (HPC) with respect to
Permeability.
1.7 OBJECTIVES OF THE PRESENT WORK
Coming up next are the motivation behind the present examination:
To evaluate the influence of various Percentages of Micro Silica on the Permeability of Concrete.
To examine the influence of different proportions of Silica Fume in combination of various Percentages of Steel Fibers
Fractions on Permeability of Concrete.
To arrive at best combination of Silica Fume and Steel Fiber content for improved Durability.
II.LITERATURE REVIEW
As mentioned earlier in the Section 1.6, need for the present study is ascertained on the basis of research reports that are
available on strength & durability characteristics of concrete containing admixtures like Micro Silica & Steel Fibers. In order to
plan the experimental program and attain the objectives defined, a comprehensive literature survey is essential. Hence in the
following text detailed literature review on strength & durability characteristics of concrete having different admixtures is presented.
2.1 INFLUENCE OF MICRO SILICA ON STRENGTH PROPERTIES OF CONCRETE
Prasad, B.K. have taken up an examination to explore the impact of replacement of cement with silica fume in the production of
High Strength Concrete. The replacement levels chosen were 0% to 20% in the increment of 5%.Thus a total of four mixtures, two
of controlled concrete with and rest of two specimens with Micro Silica concrete were used. The Compressive strength and Flexural
strength were found. The results displayed that.
Optimum replacement level of Micro Silica by 12% produced a 28 days compressive quality of 55.07Mpa.
The Flexural strength of Micro Silica concrete has increased 15% to 20% when compared to that of controlled concrete.
III.EXPERIMENTAL PROGRAMME
The following experimental program was made to find out the durability property of concrete in terms of Permeability by
usage of Micro Silica as Partial Cement replacement material along with Steel Fibers.
3.1 MATERIALS USED
The materials utilized in the test program are Cement, Coarse Aggregates, Fine Aggregates, Water, Micro Silica, Steel
Fibers, Super plasticizer.
3.1.1 CEMENT
Ordinary Portland Cement of 53 Grade confirming to IS: 12269 was used. It was tested for Physical properties. The detailed
test results are given in Table 3.1
Table 3.1 Physical Properties of Ordinary Portland Cement
S.No.
Property
Test Method
Test Result
1.
Normal consistency
Vicat Apparatus
33 %
2.
Sp. Gravity
Specific gravity bottle
3.14
3.
Initial-setting time
Final-setting time
Vicat Apparatus
75 min
200 min
4.
Fineness
Sieve test on Sieve No.
9
3.4 %
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3.1.2 COARSE AGGREGATE
In this investigation Natural Aggregates of maximum size of 20mm were used with 60% of 10mm down size Aggregates
and 40% of 20mm down size Aggregates. All the relevant tests were conducted on Coarse Aggregates to evaluate its Physical
properties. The details are shown in Table 3.2 and Table 3.3
Table 3.2 Properties of Fine Aggregate and Coarse Aggregate
Total
wt.
of
Coarse Aggregate sample = 5000 gms
Table 3.3 Sieve Analysis of Coarse Aggregate
IS Sieve No
Wt. of aggregate
retained, (gm)
% wt, retained
Cumulative %
retained
% passing
20 mm
278
5.56
5.56
94.44
10mm
4722
94.44
100.00
0.0
4.75mm
--
0.0
100.00
0.0
2.36 mm
--
0.0
100.00
0.0
1.18 mm
--
0.0
100.00
0.0
600 µ
--
0.0
100.00
0.0
300 µ
--
0.0
100.00
0.0
150 µ
--
0.0
100.00
0.0
705.56
Fineness modulus = 705.56 /100 = 7.05
3.1.3 FINE AGGREGATE
S.No.
Property
Test Results for Fine
Aggregate
Test Results for coarse
Aggregate
1
Sp. Gravity 2.62 2.72
2.
Bulk density
i) loose
ii) compacted
1640 Kg/m³
1775 Kg/m³
1452 kg/m³
1579 kg/m³
3.
Fineness modulus 3.05 7.05
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Locally accessible River Sand confirming to IS: 383 was utilized as Fine Aggregate. The Physical properties of Fine Aggregate
were explored. The details are given on Table 3.2 and Table 3.4.
Total wt. of Fine Aggregate sample = 1000 grams
Dust particle = 1000-10 = 990 grams
Table 3.4 Sieve Analysis of Fine Aggregate
IS Sieve No
Wt. of aggregate
retained, gm
%wt. retained
Cumulative %
retained
% passing
4.75 mm
20
2
2.0
98
2.36 mm
6.3
6.3
8.3
91.7
1.18 mm
32.5
32.5
40.8
59.2
600 µ
210
21.0
61.8
38.2
300 µ
320
32.0
93.8
6.2
150 µ
52
5.2
99.0
1
990
305.7
Fineness modulus = 305.7/100 = 3.05
3.1.4 WATER
Water to cementitious materials ratios between 0.34 and 0.40 are used routinely with proper inclusion of chemical admixtures, and
those as high as 0.45 and 0.52 have been used successfully. The relation between strength and water to cementitious materials ratio
is not clear for pervious concrete because unlike conventional concrete, the total paste content is less than the voids content between
the aggregates
3.1.5 MICRO SILICA
The Physical and Chemical Properties of Micro Silica are tabulated in Table 3.5and Table 3.6.
Table 3.5 Physical Properties of Micro Silica as per Manufacturer’s Literature
Average particle size, µm
Coarse Particles> 45 micron Max. 9%
Coarse Particles< 45 micron Max. 91%
Specific surface area
202 cm/gm
Bulk density(kg/m³)
500-600
Physical Form
Grey colored powdered
Table 3.6 Chemical Properties of Micro Silica as per Manufacturer’s Literature
Characteristics
Micro Silica (% wt)
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Loss on Ignition at
750 º C
Max. 4%
SiO2
85%
K2O
<1%
Na2O
<1%
Fe2O3
<1%
PH Value
8
3.1.6 STEEL FIBERS
Straight Galvanized iron Steel Fibers chopped in three different sizes with Aspect Ratio viz. 60, 70, 80, was used.
3.1.7 SUPER PLASTICIZER
Super plasticizer Conplast SP-337 Manufactured by Fosroc Chemicals (India) Limited, Bangalore, was utilized as water reducing
agent to achieve the required Workability.
3.2 CONCRETE MIX DESIGN
Using the Properties of Cement and Aggregates, Concrete mix design of M40 grade was designed as per IS 10262. The mix design
procedure and calculations are shown in Appendix A. The following proportions by weight were obtained.
Cement Fine aggregate Coarse aggregate Water-Content W/C
Ratio
450 kg/m³ 731.42 kg / m3 1210.05 kg / m3 0.192 kg/ m3 0.45
By using these proportions, a Trial mix was carried out and Compressive strength was determined. It was found that compressive
strength for 7 days was very high with these proportions. So, again by doing trials with different water content, final proportions
satisfying the strength requirements were obtained. The final proportions are as given below.
Cement Fine aggregate Coarse aggregate Water-Content W/C
Ratio
425.8 kg / m3
417 kg/m³ 1356 kg/m³ 178 kg/m³ 0.39
The above mix proportions were used throughout the experiment.
3.3 CONCRETE MIX CASES
As stated earlier, the present investigation aims at understanding the impact of Micro Silica and Steel Fibers on Coefficient
of Permeability of Various grades of Concrete. Accordingly, a total of 13 mix cases including one controlled concrete mix were
designed by considering Micro Silica in various percentages viz.5%, 7.5%, 10%, combined with Steel Fibers having three different
Aspect Ratios i.e. 60, 70, 80. Various percentage fractions of Fibers were also varied from 0.5% to 1.0% for each Aspect Ratio of
Fibers to understand its importance on Permeability of concrete. Details of 13 mix cases containing Micro Silica, Steel Fibers, etc.
are presented in Table3.7
Table 3.7 Details of Mix Cases
Mix ID Micro Silica in Concrete,
(% by weight of cement)
Aspect Ratio of Steel
Fibers
Fraction of Fibers, (% by
total wt. of concrete
ingredients)
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MC
0
--
--
M1
5
--
--
M2
7.5
--
--
M3
10
--
--
M1A1F1
5
60
0.5
M1A1F2
5
60
0.75
M1A1F3
5
60
1.0
M2A2F1
7.5
70
0.5
M2A2F2
7.5
70
0.75
M2A2F3
7.5
70
1.0
M3A3F1
10
80
0.5
M3A3F2
10
80
0.75
M3A3F3
10
80
1.0
IV.TEST RESULTS AND ANALYSIS
As mentioned earlier in section 3.5 the details of Permeability test, the Results and Analysization of Test are talked about in this
section.
4.1 PERMEABILITY TEST RESULTS
The permeability test was done on different Mix Cases of Micro Silica and Steel Fibers as describe in Table 3.7. To determine the
Coefficient of Permeability, the quantity of water percolating, Area of Specimen, time for which permeability test was done, pressure
head and thickness of specimen were observed.
The Coefficient of Permeability is calculated using the following formula.
K = _ Q___
A × T × H
L
In which,
K = Coeff. of Permeability in centimeter/second.
Q = Qty. of Water in milliliters permeating over the whole time of test after the Steady State has been reached
A=Area of the specimen in centimeter²
T =Time in seconds over which Q is measured; and
H/L= Proportion of the Pressure Head to Thickness of Sample, both indicated in similar units.
Calculated values of Coeff.of Permeability are presented in Table 4.1.
For better understanding and discussion, the Penetrability outcomes test results are exhibited in the graphical form. These graphs
will reveal the impact of silica fume and Steel filaments on performance of various grades of concrete in terms of Permeability.
4.1.1 Variation of Coefficient of Permeability of Concrete for various proportions of Micro Silica and no Steel Fibers
A graph (Figure 4.1) is drawn between concrete mix types without Steel Fibers and Coefficient of Permeability to depict the trend
of change in Coefficient of Permeability of Concrete containing various proportion of Micro Silica.
Table 4.1 Results for Permeability Test
MIX ID
Coefficient of Permeability,
x 10-5(cm/sec)
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MC 10.48
M1 9.46
M2 7.61
M3 5.42
M1A1F1 5.13
M1A1F2 4.37
M1A1F3 3.69
M2A2F1 3.72
M2A2F2 4.96
M2A2F3 10.39
M3A3F1 9.72
M3A3F2 9.62
M3A3F3 8.42
Figure 4.1 Variation of Coefficient of Permeability of Concrete with
Various Percentages of Micro Silica
4.1.2 Variation of Coefficient of Permeability of Concrete for various proportions of Micro Silica and Steel Fibers
(a) To comprehend the impact of variation of Steel strands division viz. 0.5%, 0.75%, and 1.0% with constant percentages of Micro
Silica, graphs are drawn. For 5% Micro Silica content in a concrete mixture, the relationship is shown in Figure 4.2. For 7.5% silica
fume content, the variation is shown in Figure 4.3, and for 10% Micro Silica the trend is shown in Figure 4.4.
Figure 4.2 Variation of Coefficient of Permeability of Concrete with Various
Percentage Fraction of Steel Fibers and 5% Micro Silica
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Figure 4.3 Variation of Coefficient of Permeability of Concrete with
Various Percentage Fraction of Steel Fibers and 7.5% Micro
Silica
Figure 4.4 Variation of Coefficient of Permeability of Concrete with Various
Percentage Fraction of Steel Fibers and 10% Micro Silica
(b) Graphs are drawn to indicate the influence of variation of Micro Silica viz. 5%, 7.5%, 10% and constant percentage fraction of
Steel Fibers on Coefficient of Permeability of Concrete. For 0.5% Steel Fibers content and with 60 as Aspect Ratio in Concrete
mixture, the variation is shown in Figure 4.5. For 0.755 Steel Fibers content and Aspect Ratio of 70, the relationship is shown in
Figure 4.6. For 1.0% Steel strand content and with 80 as Aspect Ratio of in Concrete mixture, the trend is shown in Figure 4.7.
Figure 4.5 Variation of Coefficient of Permeability of Concrete with Various Percentages of Micro Silica for 0.5% Steel
Fibers Fraction
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Figure 4.6 Variation of Coefficient of Permeability of Concrete with Various Percentages of Micro Silica for 0.75% Steel Fibers
Fraction
Figure 4.7 Variation of Coefficient of Permeability of Concrete with Various Percentages of Micro Silica for 1.0%
Steel Fibers Fraction
Compressive Strength:
The following testing procedure was undertaken during the cube compression testing: The measuring and testing of test specimens
was undertaken as soon as possible after being removed from curing. All specimens were tested in a wet condition and excess water
removed from the surface. The dimensions of the test specimens were measured and recorded. The platens were cleaned when
necessary to ensure no obstruction from small particles or grit.
Any loose particles were removed from the uncapped bearing surfaces of the specimens. It was ensured there was no trace
of lubricant on the bearing surfaces.
The specimens were centered on the bottom platen of the testing machine. The upper platen was lowered until uniform
pressure was provided on the specimen.
A force was applied at the required rate shown by the rotating disc on the testing machine.
Figure: Compressive Strength Test
The water is poured into the measuring jar, while the knob should be kept open so as to expel the air out. Hence creating a constant
head. Then the knob is closed and the water is poured in the jar to 1000ml, now having kept the stop watch ready, the knob is opened
and1000ml of water is allowed to flow and time required for the water to percolate through the sample is noted down.
Coefficient of permeability: The rate of flow under laminar flow conditions through a unit cross sectional area of porous medium
under unit hydraulic gradient is defined as coefficient of permeability.
where, k=coefficient of permeability (cm/sec)
a= area of graduated cylinder (cm2)
l=length of the specimen (cm)
h1=length between bent portion of the collector pipe and the 1000ml mark on the measuring jar (cm)
h2=length between bent portion to the top of the specimen (cm)
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Figure: Non porous Concrete Cubes
Figure: Porous Concrete Cubes
Figure: Curing days Cubes
Table: Compressive Strength Test in M40 Grade porous concrete
Cube S. No Curing days Load (KN) Compressive test
(N/sq.mm)
1 7 Days 330.0 38.10
320.0 38.15
315.0 39.84
2 28 Days 920.0 40.89
918.0 40.80
909.0 40.40
3 56 Days 1110.0 49.33
1090 48.44
1120.0 49.78
Figure: Compressive Strength Test in porous concrete 7 Days
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Figure: Compressive Strength Test in porous concrete 28 Days
Figure: Compressive Strength Test in porous concrete 56 Days
Figure: Comparison of different Curing Days in porous concrete Compressive Strength Test
V.DISCUSSIONS AND CONCLUSIONS
Test outcomes got for Penetrability study are given in the previous chapter along with the graphs indicating the impact of silica
fume and Steel strands on Permeability of Concrete. The outcomes are average of three specimens. In the following test, detailed
discussions are presented on the role of micro Silica and Steel strands on the performance of Concrete in terms of Coeff, of
Permeability.
5.1 VARIATION OF COEFFICIENT OF PERMEABILITY OF CONCRETE FOR VARIOUS PROPORTIONS OF
MICRO SILICA AND NO STEEL FIBERS
It is very well seen from Figure 4.1 that the test results for Coefficient of Permeability of Concrete specimen without Micro
Silica is 10.48 x 10-5 cm/sec for concrete specimen without Micro Silica. As we add Micro Silica, the coefficient of Permeability
reduces to 9.46×10-5cm/sec, 7.61×10-5 cm/sec, and 5.42×10-5cm/sec respectively for 5%, 7.5%, and 10% Micro Silica addition. The
reduction is almost 50% of that of Conventional Concrete as shown in Figure 4.8. This reduction is because of Filler effect achieved
on addition of Micro Silica.
Filler Effect: The specific surface of Micro-Silica used is greater than Cement. It is about multiple times more than the
specific Surface of Cement. This unmistakably demonstrate that the particle size of Micro Silica is much is lot little than the atom
size of Cement. Accordingly, when we add the silica fume to the plain concrete, it possesses the small spaces present between the
bond particles and furthermore in between the Concrete particles and the aggregates. Such a physical marvel is known as the Filler
effect which lessens the porousness which thusly diminishes the Penetrability.
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5.2 VARIATION OF COEFFICIENT OF PERMEABILITY OF CONCRETE FOR VARIOUS PROPORTIONS OF
MICRO SILICA AND STEEL FIBERS
(a) Variation of Coefficient of Permeability of Concrete with Various Percentage Fractions of Steel Fibers having 5% Micro
Silica
It is very well seen from Figure 4.2 that on addition of 5% Micro Silica the Permeability is 9.46×10-5 cm/sec. On adding of
Steel strands having cubic fraction 0.5%, 0.75%, and 1.0% the Permeability reduces to 5.13×10 -5cm/sec, 4.37×10-5cm/sec, and
3.69×10-5cm/sec, respectively. This is because of the adding of silica fume and Steel strands in Concrete.
(b) Variation of Coefficient of Permeability of Concrete with Various Percentage Fractions of Steel Fibers having 7.5%
Micro Silica
From Figure 4.3 it tends to be seen that on adding of silica fume 7.5% and Steel Fibers fraction 0.5%, the coefficient of
Permeability reduces to 3.72×10-5cm/sec. Again on further increasing of Steel Fibers fraction to 0.75%, and 1.0%, the coefficient
of Permeability increases from 4.96×10-5cm/sec to 10.39×10-5cm/sec. This increase in permeability is due to the Balling effect
achieved on adding of Steel strand volume fraction 0.75%. On mixing of fibers, these fibers will clump together and the pores
present in the specimen will be cracked. This might be the reason for increase in Permeability on addition of Fibers above 0.5%.
(c) Variation of Coefficient of Permeability of Concrete with Various Percentage Fractions of Steel Fibers for 10% Micro
Silica For concrete specimen having only 10% Micro Silica, the Coefficient of Permeability is 5.42 x 10-5 centimeter/second when
compared to 8.42 x 10-5 centimeter/second for specimens having 10% Micro Silica and Steel Fibers Fractions 1.0%. This indicates
that coefficient of Permeability increases as the volume portion of strands increases. This is because on addition of Micro Silica
10% and Steel Fibers Fraction 0.5%, only the filling phenomenon will takes place and there will not be any effect on the pores of
the concrete specimen.
5.3 VARIATION OF COEFFICIENT OF PERMEABILITY OF CONCRETE FOR VARIOUS PROPORTIONS OF
MICRO SILICA AND WITH STEEL FIBERS HAVING CONSTANT FRACTION
(a) Variation of Coefficient of Permeability of Concrete with various Percentages of Micro Silica for 0.5% Steel Fibers
Fraction
The Coeff.of Permeability for Concrete Mix Case having 5% Micro Silica and Steel Fiber Fraction 0.5%, the value reduces to
5.13 x 10-5 cm/sec. For 7.5% Micro Silica and 0.5% Fraction of Fibers the Coefficient of Permeability again reduces to 4.37 x 10 -5
cm/sec. But further addition of 10% Micro Silica with same 0.5% Fraction of Fibers, the Coefficient of Permeability increases to
9.72 x 10-5 cm/sec, as shown in Figure 4.5.
(b) Variation of Coefficient of Permeability of Concrete with various Proportion of Micro Silica for 0.75% Steel Fibers
Fraction
The Coefficient of Penetrability is examined for Concrete Mix Type having 0.75% Steel Fibers Fraction and by varying
Percentages of Micro Silica. It is found that on addition of Micro Silica, the Coefficient of Permeability also increases from
4.37 x 10-5 cm/sec, 4.96 x 10-5 centimeter/second, and 9.62 x 10-5 centimeter/second, for 5%, 7.5% and 10% Micro Silica content
respectively. The trend is shown in Figure 4.6 and Figure 4.8. This is because of the way that Steel strands changes the geometry
from one enormous crack to few numerous little cracks. The Steel Filaments disseminates the stresses uniformly all through the
material. So the stresses will be spread to these few little cracks which will be less penetrable than one huge crack.
Further it tends to be seen that Permeability increments as the Volume division of Strands increments. This might be because
of the reason that higher volume fraction of Fibers is likely to cause segregation and fibers bunch together which is known as
“Balling effect”. Because of Balling effect all the strands bunch together at one place in the matrix, which allows the pores present
in the matrix to breaks up. This might probably be the reason that Coefficient of Permeability increment as the volume fraction of
Fibers increments.
c) Variation of Coefficient of Permeability of Concrete with various Proportions of Micro Silica for 1.0% Steel Fibers
Fraction
It may be inferred that for Concrete Mix Type having 1.0% Steel Fiber Fraction and 5% Micro Silica, the Coefficient of
Permeability obtained is 3.69 x 10-5 cm/sec. This is about 65% less than that of Conventional Concrete. But further increase in Micro
Silica content to 7.5% and 10% along with Steel Fibers Fraction 1.0%, the Coefficient of Permeability is almost same as that of
Conventional Concrete as shown in Figure 4.8. The reason might be because of way that for a specific cubic measure of Concrete,
the insignificant adding of Micro Silica to Concrete prompts to the filling phenomenon which preceeds with just off to a specific
degree of addition of Micro Silica. Any further addition of Micro Silica, in overabundance of voids present in the concrete, will
simply increments the volume of the cementations (i.e. cement + Micro Silica) paste, and hence the overall Volume of concrete.
This is probably the reason for increase in the value of Coefficient of Permeability.
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5.4 CONCLUSIONS
These are the following Conclusions are given from the test outcomes and discussions.
Addition of 5% Micro Silica reduces the Coefficient of Permeability to 9.46×10-5 cm/sec, when compared to 10.48×10-5
cm/sec for sample without silica fume. As the addition of silica fume increases to 7.5% and 10%, the coefficient of
Permeability reduces to 7.61×10-5 centimeter/second and 5.42×10-5 centimeter/second, respectively. The reduction is about
48%.
Addition of 5% Micro Silica along with various percentages of volume fraction of Steel Fibers, the coefficient of
Permeability reduces from 5.13×10-5 cm/sec to 4.37×10-5 centimeter/second, and 3.69×10-5 centimeter/second, for
0.5%,0.75%,1.0% Volume fraction of Steel Fibers respectively. The reduction is about 65% with compared to specimen
without Micro Silica and Steel Fibers.
On addition of 7.5% Micro Silica and Steel Fibers having Aspect Ratio 70, the Coefficient of Permeability value decreases
to 3.72×10-5 cm/sec, for Steel Fiber volume 0.5%. Further increment in Volume part of Fibers to 0.75% and 1.0%, the
Penetrability value increments to 4.96×10-5 centimeter/second, 10.39×10-5 centimeter/second, respectively. This increase
in permeability is due to Balling effect.
Adding of 10% silica fume and Steel strands having Aspect Ratio of 80 does not have much effect on Permeability of
Concrete. The value slightly reduces to 9.72×10-5 centimeter/second, 9.62×10-5 centimeter/second, 8.42×10-5
centimeter/second, when compared to 10.48×10-5 centimeter/second, for concrete specimen without Micro Silica and Steel
Fibers.
Steel Fibers Aspect Ratio also affects the Coefficient of Permeability value. Steel fibers having Aspect Ratio 60 and 5%
Micro Silica, the permeability value decreases. But further adding of Micro Silica 7.5%, 10% and Steel Fibers having
Aspect Ratio 70 and 80, the Permeability value increases respectively.
For a given Aspect Ratio of Steel Fiber, Permeability of Steel Fiber Reinforced Concrete composites decrements as the
Volume portion of strand increments. The rate of decrease of Permeability however decreases with the incrimination of
Fiber content.
The best combination obtained from the test results is with the addition of 5% Micro Silica and Fibers volume fraction
1.0% and having Aspect ratio 60.
5.5 FUTURE SCOPES OF THE WORK
Further studies on durability of Concrete in terms of Permeability to verify the influence of other mineral admixtures with
or without Fibers.
Studies on Performance of Concrete in terms of improving impermeability of Concrete can be carried out by using other
type of Fibers in combination of mineral admixtures.
Investigation on durability of Concrete in terms of Coefficient of permeability may be extended to wide range of various
grades of Concrete containing mineral admixtures and Fibers.
REFERENCES
1. Beyung, Hwan Oh., “Flexural Analysis of Reinforced Concrete Beams Containing Steel Fibers”. Journals of Structural
Engineering. Vol.118 pp-1970.
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Trends in Concrete Construction. 22-24 January, 2003, CBIT, Hyderabad, India.
3. Faiz Abdullah, Mirza.M.,“Effect of Sand Replacement and Silica Fume Addition on Chloride Ion Permeability of Light
Weight Concrete”. Vol. 20, No. 1, pp- 61-73.
4. Ganesan,N., “Permeability of Steel Fiber Reinforced High Performance Concrete Composites”. Indian Concrete Journals.
January 3, 2005.
5. Julie Rapoport, Corina-Maria Aldea, S.P. Shah., “Permeability of Cracked Steel Fiber Reinforced Concrete.” Materials
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6. Vandewalle.L., “Materials and Structures. Vol.33, April 2000, pp.164-170.
7. Al MutairiNaef., Al RukaibiFahad.,“Effect of Micro Silica on Compressive Strength of Rubberized Concrete at Elevated
Temperatures”. J Marter Cycles Waste Management. Vol. 12, Septemner18, 2009. Pp 41-49.
8. Micheal D. Lepech., “Water Permeability of Engineered Cementations Composites.” Cement and Concrete
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