Evaluation of Palm Oil Fuel Ash as Mineral Filler in Hot Mix Asphalt

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


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.


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.


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


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


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.


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.


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


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.


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.


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).


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).


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.


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)


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)


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


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.


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


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)


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)


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


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


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


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


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


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.


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


Figure 3.8 Mixture being spaded in a

Marshall Mold

Figure 3.9 Marshall Compactor

Figure 3.10 Marshall Sample jacked from

Marshall Mold


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


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


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


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


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.


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.


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.


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)


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)


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)


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.


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.


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


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.


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


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


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


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


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



Asphalt Content (%), A

Bulk Density (kg/m^3) Asphalt Content (%), A

VTM (%)

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


VMA (%) Asphalt Content (%), A

VFA (%)



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


Stability (kg) Asphalt Content (%), A

Flow (mm)



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


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