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This dissertation presents a study on the laboratory evaluation of AC wearing course using POFA as filler material. A small portion of POFA (passing 75μm) was used as a 100% replacement to stone dust. POFA was incorporated by using dry process method, which considers filler as part of aggregate. ACW14 gradation with 80/100 bitumen as binder. Two sets of HMA were made with two different kinds of POFA. The two kinds of POFA varied in amount of un-burnt carbon content. A third set was made as control using conventional stone dust filler. Results showed that POFA modified samples showed better performance levels than conventional samples, but exhibited higher optimum asphalt contents. HMA modified with POFA containing high carbon content had the best Marshall Stability and Stiffness values of the 3 sets, at the same time having an OAC just a little higher than the control set. However, it exhibited VFA values below requirements.
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Juzer Naushad Moosajee, 003579 Page 1
University of Nottingham
Malaysia Campus
FACULTY OF CIVIL ENGINEERING
Evaluation of Palm Oil Fuel Ash as Mineral Filler in Hot Mix
Asphalt
By
Juzer Naushad Moosajee
April 2011
A dissertation submitted in part consideration of the degree of
BEng (Hons) in Civil Engineering
Part 2: Module H23A13
Juzer Naushad Moosajee, 003579 Page 2
ABSTRACT
This dissertation presents a study on the laboratory evaluation of Asphalt concrete wearing course using
Palm Oil Fuel Ash (POFA) as filler material. POFA, a waste product of the Malaysia Palm Oil Industry has
long been disposed in landfills and dumpsites causing serious environmental concerns. In this project, a
small portion of POFA (passing 75μm) was used as a 100% replacement to stone dust in Asphalt
Concrete mixtures. POFA was incorporated into asphalt mixes by using dry process method, which
considers filler as part of aggregate. The aggregate gradations used in this study is dense-graded ACW14
with 80/100 penetration grade bitumen as binder. POFA was collected from boilers at Seri Ulu Langat
Palm Oil Mill. Two sets of HMA were made with two different kinds of POFA. The two kinds of POFA
varied in amount of un-burnt carbon content. A third set was made as control using conventional stone
dust filler. The experiment was carried out according to Marshall Mix Design, and Marshall Stability,
Flow and Volumetric properties were used as key performance indicators. Results showed that POFA
modified samples showed better performance levels than conventional samples, but exhibited higher
optimum asphalt contents. HMA modified with POFA containing high carbon content had the best
Marshall Stability and Stiffness values of the 3 sets, at the same time having an OAC just a little higher
than the control set. However, it exhibited VFA values below requirements.
Juzer Naushad Moosajee, 003579 Page 3
ACKNOWLEDGEMENTS
I take this opportunity to express my sincere gratitude to Allah and His Holiness Dr. Syedna Mohammed
Burhanuddin Saheb for their spiritual guidance throughout this study. I thank my parents and family for
their moral and ethical support during the course of my studies. I express sincere gratitude to my
supervisor, Mr Edwin Goh Boon Hoe, whose instruction; guidance and constructive criticism were of
paramount importance throughout the study. I also thank Dr. Abdullahi Ali Mohamed for his significant
contributions during the year.
I am deeply grateful to the staff at the Civil Engineering Mixing Lab, namely Mr. Mohd Redzuan, Mr
Adzarudin Abu Zarim and Mr Elhafis A. Latiff for their technical assistance during the experimenting and
laboratory phase of this study. I extend sincere thanks to my fellow classmates and friends, Mr Sachin
Muhamad, Mr Ganim Shed Akolokwu and Mr Yhoodish Bhobeechun for their assistance during the
experimental work. I also express my special thanks to Mr. Balakrishnan a/l Renganathan and his staff at
the Seri Ulu Langat Palm Oil Mill for providing the Palm Oil Fuel Ash at no cost. Last but not the least I
thank Mr Rashid Nyagabona for his vital contributions in preparing this report.
Juzer Naushad Moosajee, 003579 Page 4
Table of Contents
Introduction .................................................................................................................................................. 6
1.1 Background Study ............................................................................................................................... 6
1.2 Objectives of the Study ....................................................................................................................... 7
1.3 Significance of the study ..................................................................................................................... 7
Literature Review .......................................................................................................................................... 8
2.1 Introduction: ....................................................................................................................................... 8
2.2 Aggregate .......................................................................................................................................... 10
2.3 Asphalt Binder ................................................................................................................................... 10
2.4 Mineral Filler ..................................................................................................................................... 11
2.5 Palm Oil Fuel Ash (POFA) .................................................................................................................. 12
2.5.1 Similarities Between POFA and Fly Ash ..................................................................................... 12
2.6 Physical Properties of Aggregates ..................................................................................................... 14
2.6.1 Bulk Specific Gravity of Aggregate, Gsb ...................................................................................... 14
2.6.2 Effective Specific Gravity of Aggregate ...................................................................................... 15
2.6.3 Aggregate Gradation .................................................................................................................. 16
2.7 Marshall Method for Obtaining Optimum Asphalt Content ............................................................. 17
2.7.1 Marshall Mixing Procedure: ....................................................................................................... 17
2.7.2 Marshall Compaction Procedure: .............................................................................................. 17
2.7.3 Volumetric Tests ........................................................................................................................ 18
2.7.4 Stability and Flow test ................................................................................................................ 18
2.7.5 Data Analysis .............................................................................................................................. 19
2.7.6 Optimum Asphalt Content (OAC) ............................................................................................... 20
Methodology ............................................................................................................................................... 21
3.1 Introduction ...................................................................................................................................... 21
3.2 Experiment Design ............................................................................................................................ 21
3.3 Physical Properties of Aggregate ...................................................................................................... 23
3.3.1 Sieving and Gradation ................................................................................................................ 24
3.4 Asphalt Cement Binder ..................................................................................................................... 25
3.4.1 Variation in Binder Content ....................................................................................................... 26
3.5 Palm Oil Fuel Ash (POFA) .................................................................................................................. 26
Juzer Naushad Moosajee, 003579 Page 5
3.6 Marshall Mixing Equipment and Procedure ..................................................................................... 27
Results ......................................................................................................................................................... 30
4.1 Introduction ...................................................................................................................................... 30
4.2 Physical Properties of Aggregates ..................................................................................................... 30
4.2.1 Aggregate Gradation .................................................................................................................. 31
4.3 Marshall Samples .............................................................................................................................. 32
4.4 Optimum Asphalt Content ................................................................................................................ 32
Discussion.................................................................................................................................................... 33
5.1 Introduction ...................................................................................................................................... 33
5.2 Volumetric Properties ....................................................................................................................... 33
5.2.1 Bulk Density ............................................................................................................................... 33
5.2.2 Void Analysis .............................................................................................................................. 33
5.3 Stability, Flow and Stiffness .............................................................................................................. 34
5.4 Optimum Asphalt Content ................................................................................................................ 34
5.5 Assessment of use of POFA as Waste Material in HMA ................................................................... 35
Conclusions and Recommendations ........................................................................................................... 39
6.1 Introduction ...................................................................................................................................... 39
6.2 Conclusions of the study ................................................................................................................... 39
6.3 Shortcoming of the study .................................................................................................................. 40
6.4 Limitations of the study .................................................................................................................... 40
6.5 Recommendations ............................................................................................................................ 40
APPENDICES ................................................................................................................................................ 41
APPENDIX A ............................................................................................................................................. 41
APPENDIX B ............................................................................................................................................. 41
APPENDIX C ............................................................................................................................................. 47
References .................................................................................................................................................. 50
Juzer Naushad Moosajee, 003579 Page 6
CHAPTER 1
Introduction
1.1 Background Study
The Malaysian palm oil industry is a major producer and exporter of palm oil and related products,
contributing 39% to world palm oil production and 44% to world exports (MPOC). The palm oil industry
contributes more to the country than just edible oil and foreign currency from exports. Palm Oil Fronds,
Palm kernel cake, empty fruit bunches are some by-products of palm oil production used to make
animal feed for the cattle and dairy industry (FFTC). Other by-products, such as palm oil shells and fibers
are used as fuel in boilers to produce steam for electricity generation. The ash from these boilers (POFA)
has little commercial value, hence disposed off in landfills or dumped in the vicinity of the factory,
causing major environmental concern. With growth in the Palm oil industry, the amount of waste POFA
continues to grow. Finding an alternate, sustainable and safe use for POFA is of high importance.
Transportation Infrastructures (roads, rail, airports and seaports) are the arteries for the free flow of
people, goods and information; three things necessary in a manufacturing and export economy
(Olebune, 2006). Road infrastructure is a major component of land based transportation; providing
transport within cities and between cities and countries. In order to maintain good road infrastructure,
strong, durable high quality road pavements are required. Extensive research has been conducted to
improve quality and performance of road pavements by modifying their individual constituents, namely:
aggregate, binder (asphalt/cement), mineral filler. Many of these researches have focused on utilization
of waste and industrial by-products so as to reduce construction costs as well as environmental
degradation. POFA is one such by-product that has been suggested and researched to a certain extent.
Abdullah et al. (2006) showed POFA to be a suitable partial replacement of OPC in aerated concrete. In
2009, Tonnayopas et al’s investivgation showed positive influence of OPFFA on properties of hardened
concrete. However, research of POFA as a suitable replacement for conventional stone dust filler in
HMA have been few and far between.
Juzer Naushad Moosajee, 003579 Page 7
1.2 Objectives of the Study
This study has the following objectives:
i. To evaluate the performance of Marshall properties of HMA with POFA as filler.
ii. To determine if presence of POFA as filler improves performance of HMA as compared to
conventional stone dust filler
iii. To determine variation in Marshall properties of the mix caused by variation in carbon content
of POFA.
iv. To assess use of POFA as waste material in HMA
1.3 Significance of the study
The road construction industry is a major consumer of raw materials in Malaysia. Due to high demand of
good quality roads, demand for raw materials is ever increasing, leading to high construction costs.
Recycling waste materials in construction is an excellent way of reducing material costs as well as
reducing the environmental impact of disposing the wastes. If POFA is shown to be a suitable additive, it
will have far reaching benefits. Its recycling will not only benefit the environment, but will also be cost
effective and sustainable while providing improved pavement performance.
Juzer Naushad Moosajee, 003579 Page 8
CHAPTER II
Literature Review
2.1 Introduction:
Hot Mix Asphalt (HMA) refers to bound layers of flexible road pavements. It derives its name from the
fact that it’s production (mixing), placement and compaction is carried out at elevated temperatures. It
is the primary placement method for large scale road projects that utilize bituminous mixtures (IRC,
2010). HMA is a very complex material that can be used for various road based applications. It can be
used as a surface course for providing good ride quality and/or as a base course for load bearing
applications. It should provide good drainage as well as be completely waterproof in all weather
conditions. All this puts numerous conflicting performance demands on the material. Improving
properties of HMA is necessary for better long lasting pavements. The concept of modifying HMA mixes
for better performance is not new. These modifications are increasingly being sought from waste
materials to promote sustainable development. Numerous studies have been carried out to incorporate
waste materials into HMA. These include (but not limited to) scrap rubber, waste glass, boiler ash,
incinerator residue, coal-plant refuse (Kandhal P. S., 1992), steel slag (Huang et al. 2007).
However, before use of waste materials in HMA is standardized, the following concerns need to be
addressed (Warren, 1991):
a) Engineering concerns:
Since the waste material will replace the conventional materials of HMA, it will affect the
engineering properties of the mix. Therefore, the HMA containing the waste material must
be reevaluated thoroughly and carefully both in the laboratory and the field.
Changes in the HMA production equipment and/or processes will be required in order to
accommodate waste materials into the production process. Storage and Handling
equipment will also have to be updated
Variation in quality and consistency of waste materials will cause variations in quality of
HMA
Juzer Naushad Moosajee, 003579 Page 9
New methods for designing, testing waste incorporated HMA may have to be developed.
Is the amount of waste materials sufficient to fulfill demands?
b) Economic concerns:
Mandating use of waste materials is likely to increase production costs of HMA e.g. costs of
collecting and transporting waste glass may be higher than costs of locally available
aggregate
Life cycle costs of HMA containing waste materials need to be determined before use in
industry. HMA incorporated with waste materials may have lesser service life even though
initial engineering properties meet required standards. This will increase it’s the life cycle
costs.
If HMA that contains waste materials is not recyclable, its disposal cost also need to be
considered.
c) Environmental Concerns:
Since HMA production involves high temperatures, use of waste materials in those
conditions may release hazardous fumes/emissions and raise concerns of air pollution.
Some hazardous components of waste materials may leach out of the HMA into the
environment, causing soil and groundwater pollution.
Use of hazardous waste materials in conventional HMA plants can compromise safety of
workers.
Non recyclable, waste incorporated HMA may pose a greater environmental concern than
the initial waste material recycled into the mix.
Juzer Naushad Moosajee, 003579 Page 10
2.2 Aggregate
Many researchers have shown how variations in aggregate properties e.g. aggregate type, gradation;
shape, durability etc have a direct impact on the performance of an HMA mix. Stephens (1974) showed
that presence of 30% or higher flat/elongated aggregate particles in asphalt concrete caused higher
VTM, resulting in a poor quality mix. Mohamed (2001) showed that variation in gradation of SMA caused
noticeable changes in Bulk Density of the compacted mixture. Research in Philippines concluded that
use of lahar (volcanic ash aggregate) from Mt. Pinatubo as fine aggregate in HRA and asphalt concrete
mixes showed improvements in performance of the road surfaces (Faustino et al. 2005). Research in
Yemen (Naji & Asi, 2008) has shown improved properties of asphalt mixtures when volcanic ash (an
abundant material) is incorporated as granular aggregate in their HMA mixes. Open-graded Base Mix is a
specialty mix containing very little or no fine aggregate, high VTM and lower OAC ranging from 1.5%-
2.5%. However, its large angular coarse aggregate content creates good interlock providing high
resistance to deformation. The mix is highly permeable and provides good drainage thanks to its high
VTM. It minimizes reflective cracking when interlaid between a concrete base and a dense HMA surface
layer (Roberts et al. 1991).
2.3 Asphalt Binder
Other research has focused on binder modification to improve the quality of HMA mixes. Binder is the
glue that holds aggregate particles together. Cement is the binder used in rigid pavements, while flexible
pavements are made with asphalt binder. Asphalt modified with SBS has shown better conventional
properties e.g. penetration grade, softening point, lower temperature susceptibility (Sengoz & Isikyakar,
2008). Asphalt modified with SBR/MMT has shown to exhibit improved visco-elastic properties, resulting
in enhanced resistance to rutting of pavements at high temperatures (Zhang et al. 2009). Hınıslıoğlu &
Ağar, (2004) also showed improvement in properties of asphalt concrete made using HDPE (High density
polyethylene)-modified asphalt binder.
Juzer Naushad Moosajee, 003579 Page 11
2.4 Mineral Filler
Another important avenue of HMA modification involves the use of mineral fillers. Mineral Fillers are
particles that pass No. 200 sieve (75µm). It is either mixed into the binder before mixing with aggregate
(wet process) or incorporated into the mixture as part of aggregate (dry process). In ACW14 gradation,
the mineral filler is considered part of the aggregate content and should be between 4% - 10% of
aggregate content (JKR, 2007). Mineral filler should be easily pulverized and free of cemented lumps,
mud-balls, and organic materials. Research into use of mineral fillers in HMA pavements dates back
more than half a decade. Puzinauskas (1969) mentioned the following roles of mineral fillers in HMA: (a)
filling interstices between aggregate particles, (b) providing contact points between large aggregate
particles, (c) acting as a bitumen extender thus creating rich and highly consistent bitumen mastic to
hold the large aggregate particles. Filler is responsible for stiffening the asphalt binder, which is
desirable to a certain extent, however too much filler will result in a dull, brittle, less cohesive mortar
(Kandhal P. S., 2009). It wasn’t until the 1970’s that legislation in US was passed to mandate use of
baghouse fines (stone dust) in HMA. These legislations were introduced primarily to enforce strict air
pollution regulations. Up until then, HMA plants blew the dust from aggregate dryers into the open
atmosphere and various other fillers were used to accommodate the deficiency in fines (Kandhal P. S.,
2009).
Many researchers have studied varying mineral fillers in order to improve the quality of flexible
pavements in their regions. In 1952, Carpenter found that asphalt mixes that contained Class F fly ash
filler had improved resistance to stripping. Dukatz & Anderson (1970) investigated the effects of eight
different filler materials on mechanical properties of HMA and concluded that different filler materials
have different effects on stiffness but almost no effect on Marshall Stability or void ratio. Asi & Assa’ad
(2005) found that asphalt concrete mixes prepared by replacing 10% of conventional stone dust filler
with Jordanian oil shale fly ash provided the best improvement in mechanical properties of the mix.
Sharma et al. (2010) concluded that bituminous mixture made using fly ash as mineral filler showed
better properties than those made with stone dust filler. Other waste fillers that have been studied
include marble waste dust (Karaşahin & Terzi, 2007), cement bypass dust (Ramzi Taha et al. 2002), coal
ash (Churchill & Amirkhanian, 1999).
Juzer Naushad Moosajee, 003579 Page 12
2.5 Palm Oil Fuel Ash (POFA)
Taking queue from other countries, Malaysia has identified POFA, an abundant waste product, as
possible substitute filler in HMA. POFA is a by-product of palm oil production. After combustion of solid
waste from extraction of palm oil, about 5% POFA by weight of combusted material is produced (Tay,
1990). The color of POFA can range from light whitish grey to dark grey due to variations in un-burnt
carbon content. Lighter shades of grey indicate low carbon content which in turn indicates high level of
combustion, while darker shades indicate vice versa i.e. high carbon content, low rate of combustion
(Abdullah et al. 2006). POFA constitutes of mainly rounded particles as shown in Fig 2.1, while chemical
analysis shows a high amount of silica and alumina compounds (Tay, 1990; Tangchirapat et al. 2006;
Borhan et al. 2010). The primary contents indicate it is a pozzolanic material (ASTM C618). Pozzolans
exhibit cementitious properties in fine particle sizes and
in the presence of water and/or calcium hydroxide (Goh
et al. 2006). Exact chemical and physical properties vary
with the conditions of the boiler (e.g. temperature,
pressure, air intake, ash capture mechanism etc.) and the
material (fuel) burned. POFA from two separate boilers is
least likely to have the exact same properties (Abdullah
et al. 2006).
2.5.1 Similarities Between POFA and Fly Ash
POFA is a product of the combustion of palm oil shells and fibers, while fly ash is product of coal
combustion. Goh et al. (2006) suggested that POFA appears to be similar to fly ash. Fly ash consists of
fine, glossy particles that are spherical in shape with some samples having hollow particles like
plerospheres and cenospheres (Sharma et al. 2010). Similar physical features are observed in
microscopic image of POFA taken by Tangchirapat et al. (2006) (Figure 2.1). Furthermore, like fly ash
(Sharma et al. 2010), POFA contains varying amounts of un-burnt carbon (Abdullah et al. 2006). In
addition, comparison of chemical analysis of POFA and fly ash (Table 2.1) show they are both rich in
siliceous compounds, indicating their pozzolanic nature (ASTM C618). They have both have been proved
to be adequate as partial replacements of OPC in concrete (Tay, 1990; Tonnayopas et al. 2009).
Juzer Naushad Moosajee, 003579 Page 13
Table 2.1: Similarities in Chemical Analysis of POFA and Fly Ash
Mineral (%)
POFA
(Tangchirapat et al.
2006)
POFA
(Borhan et al
2010)
Fly Ash
(Sharma et al.
2010)
Fly Ash
(Sharma et al.
2010)
Silicon Dioxide (SiO2) 57.71 43.6 57.5 - 61.09 56.7 - 60.1
Calcium Oxide (CaO) 6.55 8.4 0.85 - 1.3 0.5 - 0.61
Iron Oxide (Fe2O3) 3.3 4.7 3.154 - 5.4 0.9 - 1.26
Aluminum Oxide (Al2O3) 4.56 11.4
Magnesium Oxide (MgO) 4.23 4.8
Sodium Oxide (Na2O) 0.5 0.39
Potassium Oxide (K2O) 8.27
Sulfur Trioxide (SO3) 0.25 2.8
Loss on ignition (LOI) 10.52 18
POFA’s use in HMA has been studied by researchers such as Borhan et al. (2010) who found that
replacing 5% of filler content with POFA does not impair performance properties of asphalt concrete
mix. Furthermore, he found better stability values of samples modified with POFA. Modification with
POFA also improved creep resistance and fatigue life of the asphalt concrete mix, while an increase in
resilient modulus was also noted. Kamaluddin (2008) found that replacing stone dust with 100% POFA
resulted in the highest improvement in the stability and stiffnes values of SMA14.
Juzer Naushad Moosajee, 003579 Page 14
2.6 Physical Properties of Aggregates
This section will introduce methods and procedures used to test properties of aggregates. It is required
for determining the quality of aggregate used in HMA.
2.6.1 Bulk Specific Gravity of Aggregate, Gsb
Ratio of oven-dry weight in air of a unit volume of aggregate (including permeable and impermeable
voids) at stated temperature to the weight of an equal volume of gas-free distilled water at a stated
temperature (Robert et al. (1991). Procedure for determining Bulk Specific Gravity of aggregate was
referred to BS EN 812-2: 1995.
Equipment: Pycnometer, Oven, Weighing Scale
Procedure:
i. 1.5 kg of aggregate retained on 1.18mm was collected after the sieving of the aggregate. The
aggregate was collected according proportions tabled in Table 3.2.
ii. The aggregate was placed in a tray and oven dried at 110°C (±5°C) to a constant weight.
iii. It was then filled into a pycnometer and water was filled to the brim. Trapped air bubbles were
removed by shaking the pycnometer. The aggregate was then allowed to soak in water for 24
hours.
iv. After 24 hours, a slight reduction in water is observed. This is primarily due to the water being
absorbed into the aggregate voids. More water is added to fill the pycnometer to brim. Weight
of flask, aggregate and water is taken and recorded as M3.
v. Aggregate is then removed from the pycnometer into an oven tray and dried in an oven at
110°C (±5°C) to a constant weight. The weight of dry aggregate and pycnometer flask is taken to
be M2.
vi. The empty vacuum flask is dried using a towel and its weight recorded as M1.
vii. The pycnometer is filled with water up to the brim and its weight is recorded as M4.
Following formula used to obtain Bulk Specific Gravity, Gsb:
(3.1)
Juzer Naushad Moosajee, 003579 Page 15
2.6.2 Effective Specific Gravity of Aggregate
Ratio of oven dry weight of a unit volume of a permeable material (excluding voids permeable to
asphalt) at a stated temperature to the weight of an equal volume of gas free distilled water. This
procedure is conducted instead of the Theoretical Maximum Density Test (Rice Method) to obtain the
Effective Specific Gravity of Aggregate. Aggregate smaller than 1.18mm was not used in this test.
Equipment: Oven, Vacuum Flask, pump, weighing scale.
Procedure:
i. 1.5 kg of aggregate retained on 1.18mm was collected after the sieving of the aggregate. The
aggregate was collected according proportions tabled in Table 3.2.
ii. The aggregate was washed to remove any dust from the aggregate surface. It was then oven
dried at 110°C (±5°C) to a constant weight.
iii. The aggregate was placed in the vacuum flask and sealed. Water was added using the small exit
hole up to the marked limit. The hole was sealed with a valve tube. The flask was mounted on a
mechanical shaker. The Vacuum tube was attached to the flask, and the pump was attached to
the vacuum tube. A vacuum of 30mm Hg was applied for 30 minutes.
iv. After the vacuum was applied, the flask, together with the aggregate and water was weighed
and the mass recorded as M3
v. Aggregate is then removed from the vacuum flask into an oven tray and dried in an oven at
110°C (±5°C) to a constant weight. The weight of dry aggregate and vacuum flask is taken to be
M2.
vi. The empty vacuum flask is dried using a towel and its weight recorded as M1.
vii. The vacuum flask is filled with water up to the marked limit and its weight is recorded as M4.
Following formula used to obtain Effective Specific Gravity, Gse:
(3.2)
Juzer Naushad Moosajee, 003579 Page 16
2.6.3 Aggregate Gradation
Aggregate gradation was selected to conform to JKR specifications for asphalt concrete wearing courses
in Malaysia (ACW14). ACW14 produces a dense-graded mix, with almost all particle sizes passing 20mm
to filler (BS Sieve Size) incorporated into the mix. It tends to produce mixtures that have high bulk
densities and low VTM. Variations in aggregate grading of HMA mixes contribute to a significant
variation in bulk densities of the mix (Mohamed, 2001). Figure 3.2 shows the structure of dense graded
mix. Each Marshall Sample contains a total of 1200g of aggregate.
Figure 3.2 Structure of Dense-Graded Mix
Juzer Naushad Moosajee, 003579 Page 17
2.7 Marshall Method for Obtaining Optimum Asphalt Content
Sample preparation involves two major steps, mixing and compaction. ASTM D1559 is the standard
approved by the Malaysian Public Works Department (JKR) for Marshall Mix Design. The following
procedure is in accordance with the ASTM D6926.
2.7.1 Marshall Mixing Procedure:
i. Aggregate trays were prepared totaling 1200g, in proportions specified in Table 3.2. Mineral
Filler was placed in separate container.
ii. The aggregate was heated in a preheated oven to 150°C (±5°C) for around 15 min before it was
added to the mixing wok. The mineral filler was not added at this point.
iii. Appropriate quantity of asphalt, preheated to 150°C (±5°C) was added to the hot aggregate and
mixed on a medium flame until all aggregate was coated with asphalt. Filler was added at this
point and mixing continued until filler was completely incorporated into the mix. Flame was
controlled throughout mixing so that mix temperature did not exceed mixing temperature
(Table 3.4)
iv. After mixing, the mixture was allowed to cool to the compaction temperature of 150°C (±5°C).
Equipment - Oven, trays and containers, Wok, Gas and Gas Stove, Spool, Temperature Pen, Gloves
2.7.2 Marshall Compaction Procedure:
Equipment - Marshall Mold, Spatula, Marshall Hammer, Hydraulic Jack, Gloves
i. Paper disc was placed on the base plate of the mold and lubricant was sprayed inside the mold
for easy removal of the sample. Using the collar, the prepared mix was carefully added to the
mold.
ii. The mix was spaded with a spatula 15 times around the perimeter and 10 times in the interior.
The mix was spaded so that it was slightly higher than the height of the mold. Another paper
disc was placed on top of the specimen
iii. The base plate, mold and collar were placed on the pedestal of the compactor and the Marshall
hammer was placed on the specimen surface. 75 blows of the hammer were applied on the top
of the specimen.
iv. The mold was removed from the base plate, rotated 180° and replaced on the base plate so that
the bottom of the sample can be compacted.
Juzer Naushad Moosajee, 003579 Page 18
v. The Marshall mold was again placed on the pedestal and another 75 blows were applied on the
specimen.
vi. After compaction, the sample was allowed to cool inside the mold for around 30 min. The
sample was then removed from the mold using a hydraulic jack. At this point, the sample was
still hot and allowed to cool for 1 day before testing. The samples were individually labeled.
2.7.3 Volumetric Tests
These are conducted to obtain the Bulk Specific Gravity of the Compacted Mixture; Gmb. It will also give
the height of the sample which will be used to correct the Marshall Stability. The test was performed in
accordance with ASTM D6927. The procedure was as follows:
i. A vernier caliper was used to obtain the average height of each sample.
ii. The sample was then weighed in air and the dry mass (Wair) was recorded.
iii. The sample was submerged in water and its mass in water (Wsub) was obtained using a buoyancy
scale
iv. The sample was then removed from the water, surface dried with a towel and weighed to
obtain its saturated surface dry mass (WSSD).
2.7.4 Stability and Flow test
Marshall Stability and Flow is directly related to the strength and deformation characteristic of each
sample. The test was performed in accordance with ASTM D6927.
i. The samples were placed in a water bath preheated to 60°C. They were placed in a staggered
manner at three minute intervals so that each sample was heated evenly and for equal length of
time before testing. Each sample was bathed for at least 30 minutes but no longer than 40
minutes.
ii. After a sample was heated for the required amount of time, it was removed from the bath,
surface dried with a towel and immediately placed in the Marshall Stability tester. The loading
ram was brought into contact with the testing head and the flow pen was fixed into position.
The stability and flow values were zeroed.
iii. Load was then applied at a rate of 50.8mm/min until the specimen failed. At this point the
loading was stopped and the reading for stability and flow were recorded
Juzer Naushad Moosajee, 003579 Page 19
2.7.5 Data Analysis
The results obtained from the Marshall tests are used to calculate the various Marshall properties.
Formulas for Marshall Properties are tabulated as follows:
Bulk Specific Gravity of Compacted Mixture,
(4.3)
Bulk Density (kg/m3), δ
(4.4)
Theoretical Maximum Density,
(4.5)
Voids in Total Mix, VTM (%):
(4.6)
Voids in Mineral Aggregate, VMA (%):
(4.7)
Voids Filled with Asphalt, VFA (%):
(4.8)
Volume of Samples (cm3), V
(4.9)
Juzer Naushad Moosajee, 003579 Page 20
Volume, V is used to obtain the Volume Co-relation Ratio (VCR) from the VCR table (Appendix C). The
Measured Stability should be multiplied by the Volume Co-relation Ratio (VCR) to obtain the Corrected
Stability. The Corrected Stability is then converted from kN to kg. Equation below shows the full
calculation
Corrected Stability (kg) =
(4.10)
2.7.6 Optimum Asphalt Content (OAC)
Optimum Asphalt Content (OAC) is the AC at which a mix exhibits Marshall Properties that meet the
specified requirements. Very low asphalt content will result in thin asphalt film around the aggregate.
This can cause poor bond between aggregate, contamination of aggregate due to environmental factors,
high void content and early fracture cracking. Then again, too much asphalt will cause low air voids, high
plastic flow, bleeding of asphalt to the surface and an unstable pavement. Thus it is necessary to obtain
a perfect balance between the two extremes. OAC is heavily reliant on the physical properties of
aggregate, gradation, and amount and type of filler. Two procedures are generally used to obtain OAC;
NAPA procedure and Asphalt Institute Method. Asphalt Institute Method was used to obtain the OAC in
this experiment. The following steps describe the Asphalt Institute Method as mentioned in MS-2.
i. Determine the AC at maximum stability, max density and at mid-point of specified VTM range
(4% for ACW14, JKR/SPJ/2007)
ii. Average the three AC obtained from the previous steps to obtain the OAC
iii. Determine the following properties from the plotted curves using the average OAC
(JKR/SPJ/2007):
a. Marshall Stability
b. Marshall Flow
c. VTM
d. VFA
iv. Compare Values from Step 3 with JKR specification for ACW14 (Table 3.1)
Juzer Naushad Moosajee, 003579 Page 21
CHAPTER III
Methodology
3.1 Introduction
This chapter describes the design, procedures and experiment work carried out during this study. All
laboratory work was carried out at the Civil Engineering Mixing Lab, UNMC. All procedures met
specifications as set by JKR/SPJ/2007, American Association of State Highway and Transportation
Officials (AASHTO) and American Society of Testing and Materials (ASTM) unless specified. Marshall Mix
Design was used to prepare samples conforming to JKR specifications for ACW14.
Table 3.1: ACW14 Specifications (JKR/SPJ/2007)
Parameter Requirements: Wearing Course
Stability (kg) S > 500 kg
Flow (mm) F > 2.0 mm
Stiffness (kg/mm) S /F > 250 kg/mm
VTM (%) 3.0% - 5.0%
VFA (%) 75% - 85%
3.2 Experiment Design
For obtaining the objectives of this study, 3 sets of design mixes were prepared, as shown in Table 3.2:
Table 3.2 Initial Mix Design
Criteria Mix Type
Mineral Filler Stone Dust HCPF LCPF
No. of Samples 15 15 15
Asphalt Content (%) 4.5 - 6.5 4.5 - 6.5 4.5 - 6.5
No. of Samples per AC 3 3 3
Compaction (No. of blows) 75 blows / face
Juzer Naushad Moosajee, 003579 Page 22
Figure 3.1 is schematic representation of the experimental program of this study.
Collection and
Preparation of
Aggregate
Collection of
Asphalt
Collection and
Preparation of POFA
Characterization of Materials- Tests for Physical Properties of Aggregates
- Aggregate Gradation
- Sieving of Aggregate and POFA
Preparing Asphalt
Concrete Mix without
POFA
Preparing Asphalt
Concrete Mix with
LCPF
Preparing Asphalt
Concrete Mix with
HCPF
Marshall Testing of
Samples
Determination of Optimum Asphalt
Content for Each Set
Comparison of Properties of
Each Set at Optimum Asphalt
Content
Figure 3.1 Schematic Presentation of
Experimental Design
Juzer Naushad Moosajee, 003579 Page 23
3.3 Physical Properties of Aggregate
Kajang Rock Innopave Premix Sdn Bhd supplied the coarse aggregate and fine aggregate that was used
in this experiment. The coarse aggregate was crushed granite retained on 5mm BS Sieve Size, while the
fine aggregate were screened quarry fines passing 5mm. The coarse aggregate was visually inspected to
determine its shape and surface characteristics. Due to unavailability of equipments and time
constraints, only specific gravity tests were conducted. Specific Gravity Tests were conducted according
to the procedures mentioned in the literature review. The equipment and procedure have been pictured
below:
Figure 3.2 Pycnometer filled with
aggregate and water
Figure 3.3 Vacuum Flask for measuring
Effective Specific Gravity of Aggregate
Juzer Naushad Moosajee, 003579 Page 24
3.3.1 Sieving and Gradation
Equipment - BS Sieves, Mechanical Shaker, Gloves, Face Mask, Storage Containers
The aggregate was sieved by using ELE equipment conforming to BS sieve sizes. Mechanical shaker with
sieves arranged in sizes is shown in Fig 3.3.
Figure 3.4 Mechanical Shaker for Sieving
Aggregate
Juzer Naushad Moosajee, 003579 Page 25
3.4 Asphalt Cement Binder
HMA mixes prepared for this experiment used 80/100 penetration grade bitumen, which is the
commonly used grade for Malaysian conditions. It was sourced from Shell Bitumen. Table 3.3 and 3.4 list
the specifications of Shell 80/100 penetration grade bitumen as specified by the supplier.
Table 3.3 Typical Binder Properties
Typical Data ASTM Method
Penetration @ 25°C
1/10
mm 80 - 100 D5
Softening Point R & B °C 45 - 52 D36
Solubility in 1.1.1 trichloroethylene, min % 99.5 D2042
Ductility @ 25°C, min cm 100 D113
Flash Point (Cleveland Copen Cup), min °C 276 D92
Loss on Heating % 0.3 D6
Drop in Penetration after heating % 20 D5
Relative Density @ 25/25°C 1.00-1.06 D70
Table 3.4 Binder Application Temperature
Storing 120°C - 150°C
Mixing 130°C - 150°C
Compacting 120°C - 140°C
Juzer Naushad Moosajee, 003579 Page 26
3.4.1 Variation in Binder Content
The mass of aggregate, Wagg and gradation is kept constant in all samples throughout the study.
However, the mass of binder, Wb varies depending on the % AC. The table below lists the mass of binder
for each % AC.
Table 3.5 Mass of Binder, Wb per %AC
% Asphalt
Content
Mass of Binder
(g)
4 50.00
4.5 56.54
5 63.16
5.5 69.84
6 76.60
6.5 83.42
7 90.32
The values in the above table are calculated using following formula:
(3.3)
3.5 Palm Oil Fuel Ash (POFA)
The POFA used in this study was collected from Seri Ulu Langat Palm Oil Mill Sdn Bhd. The ash was
collected from the bottom of two different boilers (PFA and PFB), so that they have slightly different
chemical properties. A third sample of POFA (PFC) that was collected and used by previous year students
was still available in the university lab. These three samples of POFA were visually inspected to
determine their carbon contents with reference to each other. PFA was the darkest of all three samples
which reflected its higher carbon content and incomplete combustion. It was tagged as HCPF. PFC was
the lightest in color, reflecting its low carbon content and greater level of combustion. It was tagged
LCPF. HCPF and LCPF were separately sieved on BS No. 200 sieve (<0.075mm) to obtain the necessary
amount of filler content.
Juzer Naushad Moosajee, 003579 Page 27
3.6 Marshall Mixing Equipment and Procedure
Figure 3.6 Mixing of Samples
Figure 3.7 Checking temperature of mix with thermo pen
Figure 3.5 Aggregate arranged in a tray according to gradation
Juzer Naushad Moosajee, 003579 Page 28
Figure 3.8 Mixture being spaded in a
Marshall Mold
Figure 3.9 Marshall Compactor
Figure 3.10 Marshall Sample jacked from
Marshall Mold
Juzer Naushad Moosajee, 003579 Page 29
Figure 3.11 Buoyancy scale for measuring
volumetric properties of Marshall Sample
Figure 3.12 Marshall Samples in a water bath
Figure 3.13 Marshall Testing
Equipment
Juzer Naushad Moosajee, 003579 Page 30
CHAPTER IV
Results
4.1 Introduction
This chapter will present and discuss the results of the all the experiments carried out to complete this
study. They are presented in the form of relevant graphs and plots, with brief explanations. The terms
and properties mentioned in this chapter have been discussed in the Methodology.
4.2 Physical Properties of Aggregates
On visual inspection, it was discovered the coarse aggregate was angular and had rough surface texture.
This was expected since the aggregate was crushed granite. However, many flaky and elongated
particles were observed especially among those retained on 5mm sieve. Unfortunately, due to
unavailability of equipments, a flakiness index could not be determined, but a high value was expected,
rendering the aggregate of poor quality. Table 4.1 presents the data collected from the test for
obtaining Bulk Specific Gravity of aggregate retained on BS sieve size 1.18mm. Table 4.2 presents data
collected from test for obtaining Effective Specific Gravity of aggregate retained on BS Sieve Seize
1.18mm.
Table 4.1 Bulk Specific Gravity of Aggregates, Gsb
M1 M2 M3 M4 Gsb
835 1547 2516 2074 2.637
835 1634 2572 2074 2.654
835 1634 2570.5 2074 2.641
Avg, Gsb 2.644
Juzer Naushad Moosajee, 003579 Page 31
Table 4.2 Effective Specific Gravity of Aggregate , Gse
M1 M2 M3 M4 Gse
1737 2537 8247.5 7748 2.662
1737 2536 8244.5 7747 2.650
1737 2536 8245.5 7747 2.659
Avg, Gse 2.657071
The Effective Specific Gravity, Gse is greater than the Bulk Specific Gravity, Gsb. This fulfills the criteria for
Specific Gravities of permeable materials.
4.2.1 Aggregate Gradation
Sieved aggregate was blended to meet ACW14 specifications by JKR. A breakdown of aggregate
gradation is listed in Table 4.3
Table 4.3 Aggregate Gradation
Mix Designation ACW 14 Marshall Mix
BS Sieve Size (mm) %
Passing
%
Passing
%
Retained
Weight Retained
per sample (g)
20 100 100 0 0
14 80-95 90 10 120
10 68-90 75 15 180
5 52-72 65 10 120
3.35 45-62 50 15 180
1.18 30-45 33 17 204
0.425 17-30 18 15 180
0.150 7-16 10 8 96
0.075 4-10 5 5 60
Pan (MF, <0.075) 0 0 5 60
TOTAL 1200
Juzer Naushad Moosajee, 003579 Page 32
4.3 Marshall Samples
Initial estimate required a total of 45 samples, categorized in three sets of 15 samples with stone dust,
HCPF and LCPF as filler in one of the sets. However, due to errors and mistakes made during mixing and
testing of earlier samples, a total of 60 samples were made. Of those 60 samples, only 33 samples were
deemed to be correctly mixed and tested. In many instances, values of just 2 samples are used to obtain
the average values. Discussions and conclusions will be based on results from these 32 samples. Table
4.4 shows the final mix design.
Table 4.4 Final Mix Design
Criteria Mix Type
Mineral Filler Stone Dust HCPF LCPF
No. of Samples 10 10 12
Asphalt Content (%) 4.5 - 6.5 4.5 - 7 4.5 - 6.5
No. of Samples per AC 2 2 2
Compaction: No. of blows 75 blows / face
4.4 Optimum Asphalt Content
After data collection, graphs were plotted to show relationships of Marshall Properties in relation to AC
(%). OAC was obtained using Asphalt Institute Method. Table 4.5 lists properties of all three mixes at
their OAC.
Table 4.5 Physical and Mechanical Properties of ACW14 at OAC (%), Asphalt Institute Method
Filler OAC
(%)
Bulk
Density
(kg/m3)
VTM
(%)
VMA
(%) VFA (%)
Stability
(kg)
Flow
(mm)
Stiffness
(kg/mm)
JKR Specs - - 3 - 5 - 75 - 85 > 500 > 2.0 > 250
Stone Dust 5.6 2366 3.3 15.5 79.2 1524 4.8 317.25
LCPF 6.2 2340 3.8 17.0 78.1 1566 4.7 331.14
HCPF 5.7 2329 4.8 17.0 72.4 1711 4.5 383.81
Juzer Naushad Moosajee, 003579 Page 33
CHAPTER V
Discussion
5.1 Introduction
This section will discuss the results obtained from the experiment. It will shed light on how POFA
affected performance of the HMA and what other knowledge can be deduced about use of POFA in
HMA.
5.2 Volumetric Properties
5.2.1 Bulk Density
The use of POFA resulted in a decrease in the bulk density of the modified samples. As seen from Figure
4.1, bulk densities of samples made with POFA have lesser values than bulk densities of samples made
with stone dust. This can be explained by POFA’s lighter nature as compared to the stone dust filler.
During mixing it was noted that 60g POFA occupied almost 2 times more volume than 60g of stone dust
(Figure 4.1). Even at their OAC’s, POFA modified samples have lesser bulk density than conventional
HMA samples. More filler volume in the mix would provide more contact points for the aggregate,
which, according to Puzinauskas (1969) can be beneficial to the mix. These additional contact points may
also contribute to higher shear strength.
5.2.2 Void Analysis
POFA modified samples have VTM within JKR limits, however when compared to the control specimens,
the VTM is markedly higher (Table 4.5). Also HCPF samples had much higher VTM than LCPF samples.
POFA also caused an increase in the VMA of the samples. The VFA value of LCPF samples is well within
the JKR limit; however, for HCPF samples, the results show voids are not sufficiently filled with asphalt
(Table 4.5). This implies the asphalt film around the aggregate is thinner than required. This could lead
to accelerated cracking and aging of the pavement.
Juzer Naushad Moosajee, 003579 Page 34
5.3 Stability, Flow and Stiffness
Overall, HMA samples modified with POFA exhibited better stability and stiffness than conventional
HMA (Table 4.5). These concur with findings of Borhan et al. (2010) who found higher stability values of
samples modified with POFA. Kamaluddin (2008) also found that using 100% POFA as filler in SMA gave
the best stability and flow values. HCPF modified samples exhibited the highest stability values at a flow
slightly lower than other mixes. This contributed to its high stiffness. Presence of LCPF in HMA was also
beneficial to the stability and stiffness of the mix, returning better values than conventional HMA.
5.4 Optimum Asphalt Content
OAC of POFA modified samples was found to be higher than conventional HMA. This concurs with
Kamaluddin’s (2008) study, who also found that OAC of SMA modified with POFA was higher than OAC
of conventional SMA. The OAC of LCPF samples was found to be much higher than OAC for other mixes.
This can be attributed to higher volume of filler in the sample, which has more surface area, thus more
asphalt is required to coat the particles. Furthermore, since POFA has properties similar to fly ash (Goh
et al. 2006), it can be assumed that, like fly ash, it has higher void content than stone dust (Sharma et al.
2010). The high void content tends to absorb more asphalt, further increasing the OAC.
On the other hand, optimum conditions for HCPF were at an AC just a little higher than those for stone
dust and much lower than OAC for LCPF. Since the major difference between HCPF and LCPF is the
carbon content, it is possible that the high carbon content in HCPF acts as an asphalt extender. This
would negate the absorbing properties of the POFA, thus reducing the OAC. The high stability and
stiffness values of HCPF together with its economical OAC show that presence of high amount of un-
burnt carbon was beneficial to the strength characteristics of the mix, but reduced the VFA.
Juzer Naushad Moosajee, 003579 Page 35
5.5 Assessment of use of POFA as Waste Material in HMA
This section will assess if use of POFA as filler in HMA tackles the concerns of using waste materials in
HMA:
i. Engineering concerns: Evaluation of POFA in HMA has shown promising results in improving
engineering properties of the mix. Processing of POFA uses technology already in use in HMA
plants (e.g. sieving equipment). Other major changes during production will not be required
since equipment that handles stone dust can handle POFA. Only changes required will be in the
storage and handling sections. Larger container will be required to accommodate the larger
volumes. Storage areas should be relocated away from sources of ignition to prevent the carbon
catching fire. Testing stage did not require any changes in equipment or procedure.
Additionally, POFA is an abundant waste product in Malaysia and other palm oil producing
countries. It is likely to be sufficient to meet demands.
ii. Economic Concerns: Collection of POFA is inexpensive and because it is light and available at
Palm Oil mills all around Malaysia, its transportation is likely to be easy and cheap. Also, since no
change in production equipment is required, its use can be implemented relatively cheaply.
iii. Environmental Concerns: POFA is a product of combustion of palm fibers, shells and husks is
unlikely to contain any hazardous contents. Chemical analysis of POFA showed high level of
silicone dioxide which does not breakdown due to elevated temperatures. Levels of hazardous
wastes were negligible. Only ignitable content is carbon which does not release hazardous
emissions/fumes. Xue et al (2009) showed that asphalt is an effective stabilization and
solidification agent for heavy metal (except Ni) in MSWI ash. TCLP test for environmental impact
indicated that asphalt is an effective stabilization and solidification agent for heavy metal in
MSWI ash.
Juzer Naushad Moosajee, 003579 Page 36
2260.00
2280.00
2300.00
2320.00
2340.00
2360.00
2380.00
2400.00
4 5 6 7 8
B
u
l
k
D
e
n
s
i
t
y
(
k
g
/
m
^
3)
AC (%)
Chart 5.1: Bulk Density, δ (kg/m3) vs AC (%)
Bulk Density (kg/m^3) Stone Dust
Bulk Density (kg/m^3) LCPF
Bulk Density (kg/m^3) HCPF
Poly. (Bulk Density (kg/m^3) Stone Dust)
Poly. (Bulk Density (kg/m^3) LCPF)
Poly. (Bulk Density (kg/m^3) HCPF)
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
4 4.5 5 5.5 6 6.5 7
V
T
M
(
%)
AC (%)
Chart 5.2: VTM (%) vs AC (%)
VTM (%) Stone Dust VTM (%) LCPF
VTM (%) HCPF
Linear (VTM (%) Stone Dust) Linear (VTM (%) LCPF)
Juzer Naushad Moosajee, 003579 Page 37
14.00
14.50
15.00
15.50
16.00
16.50
17.00
17.50
18.00
18.50
4 5 6 7
V
M
A
(
%)
AC (%)
Chart 5.3: VMA (%) vs AC (%)
VMA (%) Stone Dust
VMA (%) LCPF
VMA (%) HCPF
Poly. (VMA (%) Stone Dust)
Poly. (VMA (%) LCPF)
Poly. (VMA (%) HCPF)
50.00
55.00
60.00
65.00
70.00
75.00
80.00
85.00
90.00
95.00
4 4.5 5 5.5 6 6.5 7
V
F
A
(
%)
AC (%)
Chart 5.4: VFA (%) vs AC (%)
VFA(%) Stone Dust
VFA(%) LCPF
VFA(%) HCPF
Linear (VFA(%) Stone Dust)
Linear (VFA(%) LCPF)
Linear (VFA(%) HCPF)
Juzer Naushad Moosajee, 003579 Page 38
1050.00
1150.00
1250.00
1350.00
1450.00
1550.00
1650.00
1750.00
1850.00
1950.00
4 5 6 7
S
t
a
b
i
l
i
t
y
(
k
g)
AC (%)
Chart 5.5: Stability (kg) vs AC (%)
Stability (kg) Stone Dust
Stability (kg) LCPF
Stability (kg) HCPF
Poly. (Stability (kg) Stone Dust)
Poly. (Stability (kg) LCPF)
Poly. (Stability (kg) HCPF)
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
4 4.5 5 5.5 6 6.5 7
F
l
o
w
(m
m)
AC (%)
Chart 5.6: Flow (mm) vs AC (%)
Flow (mm) Stone Dust
Flow (mm) LCPF
Flow (mm) HCPF
Linear (Flow (mm) Stone Dust)
Linear (Flow (mm) LCPF)
Linear (Flow (mm) HCPF)
Juzer Naushad Moosajee, 003579 Page 39
CHAPTER VI
Conclusions and Recommendations
6.1 Introduction
This chapter summarizes and concludes the research that was carried out to evaluate the potential of
POFA as mineral filler in HMA. It will list the shortcomings and limitations of the study and how they
affected the experiment and the results obtained. Recommendations for further research within the
scope of this study have been proposed.
6.2 Conclusions of the study
1) POFA can be successfully incorporated as mineral filler in HMA without degrading the engineering
properties of the mix.
2) POFA with high carbon content greatly improves the Stability and Stiffness of the mix without a
significant increase in OAC, but gives a low VFA value.
3) POFA with low carbon content also gives better Stability and Stiffness but requires greater asphalt
content at optimum conditions, thus making it uneconomical.
4) POFA successfully addresses some of the engineering, economic and environmental concerns of
incorporating waste materials into HMA.
Juzer Naushad Moosajee, 003579 Page 40
6.3 Shortcoming of the study
The only shortcomings of the study are that the average of only 2 replicates per AC was used instead of
the desirable 3 replicates to obtain the OAC. Errors during mixing and testing rendered 28 samples
inadequate for use in result analysis.
6.4 Limitations of the study
1) Aggregate selection was only based on the Specific gravity of the aggregate. Other physical
properties such as AIV, ACV, and flakiness index could not be determined due to unavailability of the
equipment. Lots of flaky and elongated particles were observed among the coarse aggregate,
rendering the aggregate of poor quality.
2) Tests for specific gravity, chemical analysis and carbon content of POFA specimens were not
conducted due to unavailable equipment and insufficient funding for project. As a result, a range of
desirable carbon content could not be specified.
3) Recyclability and life cycle costs of HMA modified with POFA could not be determined due to time
constraints.
6.5 Recommendations
Further research is required to better understand the science of HMA modified with POFA and expand
the scope of this study. More positive results will go a long way in convincing stakeholders of the
highway industry in Malaysia to implement POFA into their production process. The following avenues
are open for future study:
1) Evaluation of POFA as partial replacement of fine aggregate in HMA.
2) Study into the recyclability and life cycle costs of HMA modified with POFA.
3) Studying effect of POFA on properties of binder using wet process of mixing.
Juzer Naushad Moosajee, 003579 Page 41
APPENDICES
APPENDIX A
1. Mixing involved dealing with hot, flammable, volatile materials e.g. bitumen which required
safety measures for handling e.g. gloves, lab coat, safety boots, face mask
2. Sieving involved being around fine dusty particles which required dust mask to protect lungs.
APPENDIX B
Date Activity / Comments
Semester 1
Week 4
First Meeting with Supervisor, Mr Edwin Goh Boon Hoe. I was briefed
me on Palm Oil Fuel Ash, a waste material from the Palm Oil industry
and explained how change in fillers can affect properties of HMA. I was
asked to learn more about the topic and decide if I would carry out his
suggestion.
Alternatively, I was asked to propose a topic of my own in a similar
field.
Carried out research on POFA so as to obtain pre-requisites on the
subject. Learned of studies that have incorporated OPFFA into concrete
by Tonnayopas et al. Also learned of Kamaluddin (2010) who studied
use of POFA in SMA.
Studied about HMA modified with crumb rubber. This came to mind
Juzer Naushad Moosajee, 003579 Page 42
Week 6
Week 7
Week 8
after seeing Dr. Abdullahi Ali Mohamed’s presentation on aging
characteristics of HMA modified with crumb rubber (April 2010).
Decided to accept Mr Goh’s proposal since POFA was a new material
that had not been searched enough.
Second Meeting with supervisor.
Informed him of my decision to accept his proposal.
He showed a sample of POFA that contained very little amount of un-
burnt carbon. We agreed on the main objectives:
- To asses use of POFA in HMA
- To determine if and/or how variation of carbon content in POFA
affects HMA
He provided 2 files containing journal articles and reports that shed
more light on use of ash in as material in construction industry. These
were used as literature
I was asked to come up with a project proposal that would introduce
POFA as a material in HMA. Method of study would be outlined in the
proposal.
Studied articles and journals about various ways of modification of
HMA.
Visit to Civil Engineering Mixing lab as part of pavement engineering
module. Various equipments were shown that are used in Marshall Mix
design e.g. Marshall Compactor, Marshall Tester. Next day, we were
shown procedure of Marshall Mix, from mixing bitumen and aggregate
on mixing wok to compaction. Sample was tested next day.
Sieving equipment was used to sieve aggregate for Marshall Mixing as
part of pavement engineering lab.
Juzer Naushad Moosajee, 003579 Page 43
Week 9
Week 10
Week 11
Aggregate gradation conforming to ACW14 was decided upon.
Calculations were made on no. of samples and amount of aggregate
required.
Project proposal was presented to supervisor that included aggregate
gradation. Project proposal and gradation were approved and we were
instructed to start sieving.
Whole class performed Marshall Mix Design as part of Pavement
Engineering lab. We learned how to use mixing and compaction
equipment. A set of Marshall samples were prepared and tested. Data
was analyzed to be submitted as lab report.
Further online research revealed more information about the science
of fillers. Research dating back to 1952, when Puzinauskas found that
mineral fillers provide contact points between aggregate.
First week of sieving, this turned out to be really hard work. Coarse
aggregate could be easily sieved by the mechanical shaker, but sieving
fine aggregate, especially particles smaller than 0.425mm could not be
easily sieved by the automatic machine. Those particles were
eventually sieved by hand. After first day of sieving, we realized
importance of using gloves and a dust mask.
Meeting with the supervisor to inform him of the progress in sieving
and lab work. He suggested more efficient ways of sieving and also
informed us that sieving was indeed the hardest and most tedious part
of the laboratory works.
Submission of Project diary
Final meeting with supervisor for the first semester. He instructed us to
finish sieving by the start of the second semester, so that there is
Juzer Naushad Moosajee, 003579 Page 44
enough time to complete mixing and testing.
School Holiday
Break (17th
Jan – 6th Feb)
Further study in order to understand advances in pavement materials
and implementations of HMA modifications in the field e.g. Volcanic
Ash Road Building in Philippines.
Lab work involved more sieving of aggregates
Visited Seri Ulu Langat Palm Oil Mill for collection of palm oil fuel ash.
During the journey, the supervisor and I discussed the progress in lab
work and he talked about his time at university and his experience
teaching transportation engineering. He also gave insight into the road
transportation sector in Malaysia.
Semester 2
Week 1
Week 2
More sieving was done in order to obtain the required amount of
aggregates for the whole mixing procedure. POFA was characterized as
LCPF and HCPF. It was also sieved in order to obtain its finer contents
that would be used as mineral filler. Sieving POFA was much easier
since it contained more fine particles than aggregate.
By the end of the week, more than enough aggregate had been sieved
in order to complete the mixing of specimens
Bulk and Effective Gravity Tests for Aggregate were carried out to
obtain a measure of aggregate strength. These values were used
during data analysis.
First meeting of the semester with the supervisor, we reported
completing the sieving of aggregates and also showed him results of
aggregate tests.
Mixing was started, with the first set involving mixing of control
specimens having AC of 5%, 5.5% and 6 %. Control Specimens are those
that contain stone dust. They are used as benchmark for comparing
Juzer Naushad Moosajee, 003579 Page 45
Week 3
Week 4
Week 5
the POFA modified HMA. 9 samples were prepared in the first week.
Progress was slow due to inexperience in determining if mix is ready.
Also, due to oven heating problems, bitumen took a long time to reach
desired temperature.
18 samples were prepared this week. Progress was much faster as
oven problems were resolved so heating of bitumen was much faster.
Also, a prepared time table was drawn up and each person was
allocated his mixing slot to avoid clashes. By end of week 3, Control,
LCPF and HCPF containing 5%, 5.5%, and 6% AC had been mixed.
Control, HCPF and LCPF samples containing AC of 4.5% were prepared.
Total of 9 samples were prepared.
Samples prepared over the last 2 weeks were tested for their
volumetric and Marshall properties. However, 2 samples did not yield
results due to unexplainable circumstances.
All data obtained was analyzed using MS Excel SpreadSheet Program.
Values obtained were plotted on graphs and studied over the
weekend. Graphs showed grave inconsistency. Stability values
decreased from 4.5% onwards, only slightly increasing at 6%.
Volumetric properties did not follow regular patterns
Introduction part of the report was completed over the weekend
Results were presented to the supervisor in order to get his input. He
asked about any mistakes in the mixing/testing phase. Eventually it was
realized that we made an error while testing the first 27 specimens. All
of those specimens were left for more than 1 day before testing. He
explained testing a specimen after more than one day can yield below
par results since specimen is allowed to dry beyond recommended
time. Also those 27 specimens were incorrectly stacked on top of each
Juzer Naushad Moosajee, 003579 Page 46
Week 6 – 7
Week 8 - 12
other which resulted in inconsistent void values. 4.5% samples were
deemed usable.
Since it was already mid semester he suggested remixing control
samples so as to obtain at-least 1 set of results that could be discussed.
Amount of aggregate left was calculated. Based on our calculations, we
determined that 2 samples per AC for each set could be mixed without
requiring too much sieving.
This was proposed to the supervisor and after his approval we finished
the necessary sieving by the end of the week.
Mixing of samples resumed. Experience from previous mistakes had
taught us how to avoid most errors and this was reflected in
consistency of the new results. By end of week 9, all required samples
of control, LCPF, HCPF and NPF had been prepared and tested.
Results were analyzed as mentioned before and were presented to the
supervisor who approved the new consistent values.
At the end of the experiment, it was obvious that the most tedious part
of the experiment was sieving the aggregate. Mixing and testing could
be done at a much faster pace.
These 4 weeks were used to write the final year dissertation that
would be submitted as
Juzer Naushad Moosajee, 003579 Page 47
APPENDIX C
Table 4.3 Aggregate Gradation
Mix Designation ACW 14 Marshall Mix
BS Sieve Size (mm) %
Passing
%
Passing
%
Retained
Weight Retained
per sample (g)
Total Weight of
Aggregate Sieved
20 100 100 0 0 0
14 80-95 90 10 120 7200
10 68-90 75 15 180 10800
5 52-72 65 10 120 7200
3.35 45-62 50 15 180 10800
1.18 30-45 33 17 204 12240
0.425 17-30 18 15 180 10800
0.150 7-16 10 8 96 5760
0.075 4-10 5 5 60 3600
Pan (MF, <0.075) 0 0 5 60 3600
TOTAL 1200 72000
Juzer Naushad Moosajee, 003579 Page 48
Juzer Naushad Moosajee, 003579 Page 49
Asphalt Content (%), A
Bulk Density (kg/m^3) Asphalt Content (%), A
VTM (%)
Stone Dust LCPF HCPF
Stone Dust LCPF HCPF
4.5 2323.98 2278.64 2292.71
4.5 6.22 8.05 7.48
5 2323.10 2302.46 2317.21
5 5.55 6.39 5.79
5.5 2382.53 2322.83 2331.94
5.5 2.42 4.86 4.49
6 2366.30 2346.51 2319.96
6 2.37 3.18 4.28
6.5 2365.21 2342.12 2319.81
6.5 1.70 2.66 3.58
7
2318.77
Asphalt Content (%), A
VMA (%) Asphalt Content (%), A
VFA (%)
Stone Dust LCPF HCPF
Stone Dust LCPF HCPF
4.5 16.70 17.71 17.20
4.5 61.56 54.59 56.50
5 16.54 17.28 16.75
5 66.43 63.03 65.42
5.5 14.85 16.99 16.66
5.5 83.75 71.40 73.06
6 15.88 16.59 17.53
6 85.16 80.82 75.59
6.5 16.37 17.18 17.97
6.5 89.63 84.55 80.08
Asphalt Content (%), A
Stability (kg) Asphalt Content (%), A
Flow (mm)
Stone Dust LCPF HCPF
Stone Dust LCPF HCPF
4.5 1218.05 1389.47 1555.69
4.5 3.59 3.57 3.24
5 1497.02 1429.42 1836.69
5 4.31 3.50 3.00
5.5 1592.33 1679.15 1692.08
5.5 4.12 3.72 4.37
6 1325.76 1585.24 1601.05
6 5.91 5.02 5.31
6.5 1112.33 1446.57 1200.20
6.5 5.41 4.94 5.14
Juzer Naushad Moosajee, 003579 Page 50
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