PERPUSTAKAAN UMP

I VU IV 111111111111111 U 0000098347

UTILIZATION OF WASTE HIGH DENSITY POLYETHYELEN (HDPE) AS A

COURSE AGGREGATE REPLACEMENT WITH FLY ASH AS FILLER ON HOT MIX

ASPHALT

NORASHIK1N BINTI ABD RAZAK

Thesis submitted in fulfilment of the requirements for the award of the B. Eng (Hons.) Civil Engineering

Faculty of Civil Engineering and Earth Resources UNIVERSITY MALAYSIA PAHANG

JANUARY 2015

VI

ABSTRACT

This researched is conducted to investigate the waste HDPE as a coarse aggregate replacement with fly ash as filler on hot mix asphalt The materials used in this studyare using 80/100 grade penetration of bitumen This study focused on three objectives by.usmg ACW14 for determining the optimum bitumen content,;I stiffness modulus andipermanent deformation behaviour using waste HDPE as coarse aggregatereplacemëntbwithflyjash filler on hot mix asphalt. The modified asphalt mixture will be produced fromthe content of waste HDPE in flakes form in range between 2.0%, 4.0%, 60 %, 8.0 %and,10.0%of the asphalt mixture with sieve size 3.35 mm to 1.18 mm. At 5.37 % of optimum bitumen content as followed the hot mix asphalt wearing course 14 (ACW14) was accordance to Public Work Department (PWD) 2008 standard. The samples was tested on Repeated Load Axial Test (RLAT) with 1800 cycles load and axial load applied is 100 kN to determine permanent deformation of modified and unmodified asphalt mixture. The samples; were tested using Indirect Tensile Stiffness Modulus Test (ITSM) to investigate the stiffness modulus modified asphalt mixture at 30 °C. From the results obtain from lab work for the minimum permanent deformation of modified asphalt was 4.0 % of HDPE content. However, the maximum stiffness of HDPE modified asphalt mixture at 4.0,% of .HDPE content. Therefore, HDPE modified asphalt can resist the previôusly mentiänëd road failure, act as environmental friendly and in economic aspect and also found thaVit is suitable to use for road pavement. -

ABSTRAK

Kajian mi dijalankan untuk menyiasat sisa HDPE sebagai pengganti agregat kasar dengan abu terbang sebagai pengisi pada campuran asfalt panas. -Bahan-bahan yang digunakan dalam kajian mi adalah menggunakan 80/100 penembusan gred bitumen. Kajian mi memberi tumpuan kepada tiga objektif dengan menggunakan ACW14 untuk meñentukan kandungan bitumen optimum, kekakuan modulus dan kelakuan ubah bentuk kekal menggunakan sisa HDPE sebagai pengganti agregat kasar dengan pengisi abu terbang pada campuran asfalt panas. Campuran asfalt diubahsuai akan dihasilkan daripada kandungan sisa HDPE dalam bentuk kepingan dalamjulat antara 2.0 %, 4.0 %, 6.0 %, 8.0 % dan 10.0 % dàripada campuran asfalt dengan saiz ayak 3.35 mm untuk 1.18 mm. Pada 5.37 % daripada kandungan bitumen optimum yang diikuti campuran asfalt panas memakai kursus 14 (ACW14) adalah selaras dengan Jabatan Kerja Raya (JKR) 2008 standard. Sampel telah diuji ke atas beban berulang ujian paksi (RLAT) 1800 dengan kitaran beban dan beban paksi digunakan adalah 100 kN untuk menentukan ubah bentuk kekal campuran asfalt diubahsuai dan tidak diubah suai. Sampel yang diuji menggunakan tegangan Tidak langsung tegangan Kekakuan Modulus Ujian (ITSM) untuk menyiasat kekukuhan modulus campuran asfalt diubahsuai pada 30 °C. Daripada keputusan mendapatkan dari, kerja rnakmal untuk ubah bentuk kekal minimum asfalt terubahsuai adalah 40 %daripada kándungan HDPE. Walau bagaimanapun, kekakuan maksimum HDPE diiibahsüai campuran asfalt pada 4.0 % danipada kandungan HDPE. Oleh itu, HDPE asfalt diubähsuai dapat menahan kegagalan jalan yang dinyatakan sebelum mi, bertindak sebagai mesra alam sekitar dan dalam aspek ekonomi dan juga mendapati bahawa ia adalah sesuai untuk digunakan untuk turapan jalan.

VI,

TABLE OF CONTENTS

VIII

Page

SUPERVISOR DECLARATION 11

STUDENT DECLARATION 111•

DEDICATION

iv

ACKNOWLEDGEMENT V

ABSTRACT vi

ABSTRAK vi'

TABLE OF CONTENT viii

LIST OF TABLES xiii

LIST OF FIGURES xiv

LIST OF SYMBOLS xvi

LIST OF ABBREVIATIONS xvii

CHAPTER 1 INTRODUCTION

1.1 Introduction 1

1.2 Problem Statement 2

1.3 Objectives of Study 2

1.4 Scopes of Study 2

1.5 Research Significance 3

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 4

2.2 Hot Mix Asphalt 4

2.3 Materials 5

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2.3.1 Course Aggregate 6 2.3.2 Fine Aggregate 6 2.3.3 Aggregate Gradation 6 2.3.4 Aggregte Properties - 7

2.4 Bitumen 7

2.5 Mineral Filler 8

2.5.1 Type of Mineral Filler 8

2.5.1.1 Cement 8 2.5.1.2 Hydrated Lime 9 2.5.1.3 Limestone Dust 9

2.5.2 Mineral Filler Gradation 9

2.6 Fly Ash 10

2.6.1 Production of Fly Ash 11 2.6.2 Characteristic of Fly Ash 11

2.6.2.1 Size and Shape 11 2.6.2.2 Chemistry 12 2.5.2.3 Colours 13

2.7 Fly Ash in Asphalt Pavement 13

2.8 Polymer 14

2.8.1 High Density Polyethylene (HDPE) 14 2.8.2 HDPE Modified Asphalt 15

CHAPTER 3 RESEARCH METHODOLOGY

3.1 Introduction 16

3.2 Sample Planning of Materials 17

3.2.1 Aggregate Gradation 17 3.2.2 Aggregate 17 3.2.3 Bitumen 18 3.2.4 High Density Polyethylene (HDPE) 19

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3.2.5 Fly Ash 20

3.3 Sample preparation 20

3.4 Laboratory test 22

3.4.1 Aggregate Gradation 22 3.4.2 Optimum Bitumen Content (OBC) 23

3.5 Los Angeles Abrasion Test (LA) 23

3.6 Aggregate Crushing Value Test (ACV) 24

3.7 Aggregate Impact Value Test (AIV) 26

3.8 Ten Percent Value Test (TPV) 27

3.9 Penetration Test 28

3.10 Softening Point Test 29

3.11 Density and Void Analysis 30

3.11.1 Voids in Total Mix (VTM) 30 3.11.2 Voids in Mineral Aggregate (VMA) 31 3.11.3 Voids in Filled with Asphalt (VFA) 31 3.11.4 Bulk Density 32

3.12 Indirect Tensile Stiffness Modulus Test (ISTM) 32

3.13 Repeated Load Axial Test (RLAT) 34

CHAPTER 4 RESULT AND DISCUSSION

4.1 Introduction 36

4.1.1 Aggregate Gradation Result 37

4.2 Performance Quality of Bitumen and Aggregate 37

4.3 Density and Voids Analysis 38

4.3.1 Density and Void Analysis for Unmodified Asphalt 38 4.3.2 Voids in Total Mix (VTM) for Unmodified Asphalt 39

4.3.3 Voids in Mineral Aggregate (VMA) for Unmodified Asphalt 40

4.3.4 Voids Filled Asphalt (VFA) for Unmodified Asphalt 41 4.3.5 Bulk Density for Unmodified Asphalt 42 4.3.5 Optimum Bitumen Content for Unmodified Asphalt

and Modified Asphalt 43

4.4 Indirect Tensile Stiffness Modulus Test (ITSM) 43

4.4.1 Indirect Tensile Stiffness Modulus Test (ITSM) for unmodified asphalt 44

4.4.2 Indirect Tensile Stiffness Modulus Test (ITSM) for modified asphalt 45

4.5 Repeated Load Axial Test (RLAT) 46

4.5.1 Repeated Load Axial Test of Modified Asphalt (HDPE with Portland Cement), 46

4.5.1 Repeated Load Axial Test of Modified Asphalt (HDPE with Fly Ash) 47

CHAPTER 5 CONCLUSION AND RECOMMENDATION

5.1 Conclusion 49

5.2 Recommendation 50

REFERENCES 51

APPENDICES 53

Al Performance Quality of Aggregate and Bitumen 53

A2 Density and Void Analysis Result for Unmodified Asphalt

Sample 55

A3 Example Calculation of Density and Void Analysis for

Unmodified Asphalt Sample 56

A4 Indirect Tensile Stiffness Modulus Test for Unmodified Asphalt

Sample 58

AS Indirect Tensile Stiffness Modulus Test for Modified Asphalt

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XII

Sample (HDPE with Portland cement) 59

A6 Indirect Tensile Stiffness Modulus Test for Modified Asphalt

Sample (HDPE with Fly Ash)

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A7 Repeated Load Axial Test for Unmodified Asphalt Sample 61

A8 Repeated Load Axial Test For Modified Asphalt Sample

(HDPE with Portland Cement) 64

A9 Repeated Load Axial Test For Modified Asphalt Sample

(HDPE with Fly Ash) 65

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Course aggregate for bituminous mix 6

2.2 Gradation limits for asphaltic concrete 7

2.3 Gradation for mineral filler 9

3.1 Gradation limit for ACW14 17

3.2 Design bitumen content 18

3.3 Indirect Tensile Stiffness Modulus Test (ISTM) parameter 33

3.4 Repeated Load Axial Test (RLAT) parameter 34

4.1 Gradation of aggregate limit for mix ACW14 37

4.2 Performance quality of bitumen and aggregate 38

4.3 PWD requirement for asphalt mixture 38

4.4 Optimum bitumen content value 43

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Fly ash particles at 2000x magnification 12

2.2 Typical ash colours 13

3.1 Aggregate 18

3.2 Bitumen 19

3.3 High Density Polyethylene (HDPE) 19

3.4 Fly Ash 20

3.5 Experimental design flow 21

3.6 Grain size distribution curve 22

3.7 Los Angeles Abrasion (LA) 24

3.8 Aggregate Crushing Value (ACV) 25

3.9 Aggregate Impact Value (MV) 27

3.10 Penetration Test 28

3.11 Softening Point Test 29

3.12 Indirect Tensile Stifthess Modulus Test (ITSM) 34

3.13 Repeated Load Axial Test (RLAT) 35

4.1 Air void in total mix versus bitumen content for unmodified asphalt 39

4.2 Voids in mineral aggregate (VMA) versus bitumen content for Unmodified Asphalt 40

4.3 Relationship between voids filled with asphalt (VFA) versus bitumen content for unmodified asphalt 41

4.4 Bulk Density versus bitumen content for unmodified asphalt 42

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xv

4.5 Stiffness Modulus versus bitumen content for unmodified asphalt 44

4.6 Stiffness modulus versus HDPE content for unmodified and modified asphalt 45

4.7 Axial Strain of I[DPE with Portland Cement 46

4.8 Axial Strain of HDPE with Fly Ash 47

4.9 Axial Strain of unmodified and modified asphalt 48

LIST OF SYMBOLS

d - Bulk density

Gmb - Bulk specific gravity of the mix

Pw - Density of water

WD - Mass of specimen in water

WSSD - Mass of specimen in water

WSUB - Mass surface dry mass

Gmm - Maximum theoretical specific gravity of the mix

Pb - Percent by weight of the mix

Gse - Effective specific gravity of the mix

Gb - Specific gravity of asphalt binder

Gb - Bulk specific gravity of the aggregate

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LIST OF ABBREVIATIONS

AC - asphaltic Concrete

ACW - asphaltic Concrete (Wearing Course)

ASTM - American Society for Testing and Materials

HDPE - High Density Polyethylene

HMA - Hot Mix Asphalt

UTM - Universal Testing Machine

PWD - Public Work Department

OPC - ordinary Portland cement

AASHTO - American Association of State Highway and Transportation Officials

LA - Lost Angeles Abrasion

ACV - Aggregate Crushing Value

AIV - Aggregate Impact Value

TPV - Ten Percent Value

ITSM - Indirect Tensile Stiffness Modulus Test

RLAT - Repeated Axial Load Test

OBC - Optimum Bitumen Content

MATTA - Material Testing Apparatus

TMD - maximum theoretical density

VTM - voids in total mix

VMA - voids in mineral aggregates

VFA - voids filled with asphalt

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CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION

In Malaysia., roads and highways are an important role to connect a destination

to another destination. There are two types of pavement are used which are flexible

pavement and rigid pavement. As all know, the flexible pavement is often used because

it is easy to maintain, have-low cost and can be constructs easily.

Over the years, road structures have experienced failures rapidly than expected

due to the increase of traffic volume and insufficient degree of maintenance. Therefore,

it needs to minimize the major failure and increase the long term durability of a flexible

pavement. The bituminous layers had been taken to improve performance asphalt

properties such as resistance to rutting, permanent deformation, cracking, fatigue and

stripping. The usage of high quality asphalt is the way of increasing the quality of

material layer.

The use of fly ash as a filler in asphalt mixture can be utilized as an alternative

solution to flexible pavement damage problems. The effect of fly ash as a filler on the

mechanical properties of asphalt mixture was found that fly ash can be effective in a

dense-graded wearing course as a filler (Tapkin et al.,2008). Now, the fly ash has been

taken to consideration in order to reduce costs and beneficial environmental can be

identified for the industrial material. In the other hand, the waste HDPE replace as

coarse aggregate in asphalt mixture is preferentially solution for increasing the cost

savings and reduces the energy consumption and environmental pollution.

1.2 PROBLEM STATEMENT

As all know, the increase in traffic loading for many centuries until now have

experiences failures of their transportation infrastructure. Besides, the flexible pavement

also faced the major • failures modes for pavements such as rutting, permanent

deformation, fatigue cracking, low-temperature cracking several measures has been

continuously done to improve the pavement quality and the methods of structure design.

The sources of improvement were providing the modified engineering properties in

asphalt mixture for weathering and deformation problems to make the best result in road

surface layer.

1.3 OBJECTIVES OF STUDY

In this study, the modification of asphalt mixture using waste I{DPE as coarse

aggregate with fly ash as filler by using asphalt concrete wearing 14 (ACW 14). Based

on Universal Testing Machine (UTM) the experimental work had been done. The main

objectives of this study are:

1. To determine optimum bitumen content of asphalt mixture

2. To investigate stiffness modulus of modified asphalt by using Indirect Tensile

Stiffness Test (ITSM)

3. To determine permanent deformation behavior of modified asphalt by using

Repeated Load Axial Test (RLAT)

1.4 SCOPES OF STUDY

The main focus of this research is to utilize of waste HDPE as coarse aggregate

replacement with fly ash as filler on Hot Mix Asphalt (HM) Therefore, waste HDPE

and fly ash as filler is the main materials used. The properties of unmodified and

modified sample of asphalt are provided for flexible pavement and ACW14 of

3

aggregate gradation size is used for both samples. In this study, bitumen 80/100

penetration grade will be used in construction and maintenance of flexible pavement.

In addition, waste HDPE will be used to replace coarse aggregate size between

3.35 mm until 1.18 mm. The coarse aggregate has to be replaced by waste HDPE in

flakes that form in five different percentages which is 2.0 %, 4.0 %, 6.0 %, 8.0 % and

10.0 % with on three samples for each percentage for asphalt mixture modification

purpose and investigate stiffness modulus of ACW14 by using fly ash as filler. The

result of the density and voids analysis are use to determine the optimum bitumen

content by doing experiment work on voids in total mix (VTM), voids filled asphalt

(VFA), bulk density and stiffness modulus from the modified samples and unmodified

samples will be compared and analyze the data according to specification stated in

PWD 2008 standard. In this study, there are several testing will be conducted which is

softening point, penetration test and Indirect Tensile Stiffness Modulus Test (ITSM) for

finding the stiffness modulus and also Repeated Load Axial (RLAT) to determine the

permanent deformation behavior.

1.5 RESEARCH SIGNIFICANCE

The world transportation is dynamic and it is expanding over the time. Road

defect such as permanent rutting are the one of the most dangerous forms of distress in

the pavement and it will cause an increases in vehicle accidents. In order to reduce the

structural failure of the pavement and improved the service life of the road. Many

researcher proved that polymer modified asphalt has become a fact of life for the road

construction. By improving the properties of permanent deformation performance of

asphalt concrete pavement, it will increase the life service of pavement.

Besides, the replacing High Density Polyethylene (HDPE) in asphalt is to avoid

environmental problems resulting from plastic solid waste disposal. By using waste

Polymers to modify the asphalt, it is proved to be an ideal way, not only for solving the

Pollution problem in our country, but also for improving the performance of asphalt

(Amjad et al., 1999). From this study, we can observe the performance of High Density

Polyethylene (HDPE) for modified asphalt mix in the ACW14 samples.

CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

In Malaysia and other countries used a various types of bituminous pavement.

Bituminous pavement is very widely used because it has many advantages such as long

life design and is able to play a role as a medium of communication that has high

durability and serviceability.

Time by time the increased of traffic load is caused by the characteristics of

durability and serviceability bituminous paving. As known, the road is most important

communication media in everywhere. The characteristics of durability and

serviceability are depends on the strength, stiffness and stability of the pavement. A

flexible pavement is a layered structure consisting of the sub base, road base, followed

by the sub-base layer, the base, binder course and wearing course.

2.2 HOT MIX ASPHALT

According to Industrial Resources Council (2008), asphalt concrete pavement,

or Hot Mix Asphalt (HMA) pavement as its most commonly refers to the bound layers

of a flexible pavement structure. Asphalt concrete is placed as HMA, which is a mixture

Of coarse and fine aggregate, and asphalt mixture. HMA is mixed, placed and

compacted at elevated temperature, hence the name. Asphalt concrete pavement has

been placed at ambient air temperatures and also H1MA is the primary placement

method for roads and interstates. The HMA is typically applied in 4 inch to 8 inch thick

5

layers, with the lower layers acting to support the top layer known as the surface. The

aggregate in the surface course are chosen for their friction properties and durability.

When designing a HMA pavement the aggregate used must be strong and

durable and have a good angular shape to help resist rutting. The fine aggregate is used

to fill in the voids between the coarse particles, which that increased the density of the

asphalt concrete and provides load transfer between the larger particles. The asphalt

binder is typically used on 5.0 % - 6.0 % of the mixture and serves to bid the aggregate

together. The 95 percent by weight of HMA mixtures is aggregate the coarse and fine

aggregate properties influence pavement performance significantly. This study has

shown that }JMA pavement of rutting and stripping to be directly related to improper

selection and use of aggregates (Chang, 2005).

2.3 MATERIALS

The flexible road pavements consist of discrete layers. The sub-base provides

strength and a solid platform, the binder course is the main load bearing layer and the

surface course protects the lower layers from the weather and provides an even skid

resistant running surface. Aggregates used in road pavements may be unbound or bound

by asphalt binder. Unbound layers are usually used for the sub-base but may

occasionally be used in the case of minor roads for the whole structure.

Aggregate comes from either natural or manufactured sources. Natural

aggregates come from hard rock, there are three broad geological classifications

included:

i. Igneous rock - these stones are primarily crystalline and are' shaped by

the cooling of molten rock material beneath the earth's crust (magma).

ii. Sedimentary rocks - these stones are formed from depositing insoluble

material (existing rock deposited on the bed of an ocean or lake). This

material is transformed to rock by heat and pressure. Sedimentary rocks

are layered in appearance and are further classified based on their

6

predominant mineral as calcareous (limestone, chalk, and so forth), slices

(sandstone, etc.) or argillaceous (shale, etc.)

Metamorphic rock - these are igneous or sedimentary rocks that have

been subjected to heavy press and passion enough to change their mineral

structure so as, to be different from the original stone

2.3.1 Course Aggregate

Coarse aggregates can be material substantially retained on 2.36 mm sieve

opening (sieve no.8). It is shall be crushed rock or crushed gravel and make free from

foreign materials or dust and other organic matter. The coarse aggregate will provide

stability to the bituminous pavement and make conform to physical and mechanical

quality requirement.

Table 2.1: Course aggregate for bituminous mix

Quality Test Methods Requirements Loss Angeles abrasion ASTM C131 -69 Not more than 25 %

Flakiness index MS 30 Not more than 25 % Water Absorption MS 30 Not more than 2 %

2.3.2 Fine Aggregate

Fine aggregate shall be material passing a 2.36 mm sieve opening. It is shall be

clean screening quarry dusts. It is shall be non-plastic and free from the clay

aggregation of material, and other organic matter. The fine aggregate has been produced

by crushing stone or gravel conformed to physical and mechanical quality requirements.

2.3.3 Aggregate Gradation

The particle size distribution of an aggregate or gradation is one of most

influential characteristics. On hot mix asphalt, the gradation makes it helps to determine

almost every important property which is stiffness, stability, durability, permeability,

workability, fatigue resistance, frictional resistance and resistance to moisture damage.

7

Gradation is usually measured by using a sieve analysis. In a sieve analysis, a sample of

dry aggregate of weight is separated through a series of sieves with progressively

smaller openings. When separated, the weight of particles retained on each sieve is

measured and compared to the total sample weight. The information Table 2.2 indicates

that gradation limit for asphaltic concrete.

Table 2.2: Gradation limits for asphaltic concrete

Mix Type ACW 10 ACW 14 ACB 28 BS Sieve Size (mm) Percentage Passing by Weight

28.0 - - 100 20.0 - 100 72-90 14.0 100 90 -100 58-76 10.0 90 -100 76-86 48-64 5.0 58-72 50-62 30-46

3.35 48-64 40-54 24-40 1.18 22-40 18-34 14-28

0.425 12-26 12-24 8-20 0.150 6-14 6-14 4-10 0.075 4-8 4-8 3-7

Source: PWD 2008 Standard

2.3.4 Aggregate Properties

Aggregates properties can be separated into three parts which is a mineral,

chemical and physical properties. There is most significantly, that the physical

properties can be most affected on aggregates in the mixture.

2.4 BITUMEN

The asphalt binder component of an asphalt pavement typically makes up about

5 to 6 percent of the total asphalt mixture and binds the aggregate particle together.

Bitumen is used in hot mix asphalt and used as the binder in surface treatments and mix

asphalt pavements. The properties of binders are often improved or enhanced by using

additives or modifiers to improve adhesion, flow, oxidation characteristics and

elasticity.

8

Type binder in the mixture has a great impact on the durability of asphalt

concrete. In this study bitumen is used as a binder. Bitumen properties also - depend on

the nature of the binder and the binder aging has been occurs bitumen from the

production process, storage, transportation to the mix. Mixture becomes brittle if the

binder experiencing excessi'e hardening and happens when the mixture occurs at very

high temperatures for too long life. The main function of bitumen in the mix is a good

bond between the aggregate and provide an impervious material at affordable prices

selection of fasteners depends on the type of mix, long service life, environmental and

climatic conditions, and traffic engineering features.

2.5 MINERAL FILLER

Mineral filler consists of very fine, inert mineral matter that is added to the hot

mix asphalt to improve the density and strength of the mixture. It shall be in corporate

as part limestone aggregate gradation and it shall be of finely divided mineral matter of

limestone dust or hydrated lime. Not less than 70 percent by weight shall pass 0.075

nmi (No. 200) sieve. The total amount of mineral filler shall limited such that the ratio

of the combined coarse aggregate, fine aggregate and mineral of final gradation passing

0.075 mm sieve of bitumen, by weight shall be in range of 0.6 mm to 1.2 mm. The

mineral shall also treated as anti-stripping agent (PWD, 2008)

2.5.1 Type of Mineral Filler

There are a various materials have been used as a fillers in bituminous pavement

mixture. It will consist of finely divided mineral matter such as cement, hydrated lime,

and limestone dust. Besides these materials, there are new discoveries to replace this

natural material which is the physical properties, chemical, and mechanical properties of

the material are same or better than existing materials.

2.5.1.1 Cement

The material is often used as filler in bituminous mix is cement. Cement commonly used is the type of ordinary Portland cement (OPC). It is capable of

9

increasing the viscosity and hardness of bitumen. Filler material will influence the

ductility and porosity of the mixture by heating or increasing temperature. Cement

consumption will also lower the softening point temperature of bitumen.

2.5.1.2 Hydrated Lime

A mineral used in road construction is hydrated lime. Portland cement can be

used for replace hydrated lime. Amount of hydrated lime are usually added in a pre

mixture is in 1 to 2 percent by weight of the mixture. Hydrated lime is removers anti

nice addition of hydrated lime can also reduce the effect of the former tire and the road

surface,- improve strength and reduce fractures in road (National Lime Association,

2003).

2.5.1.3 Limestone Dust

Limestone is sedimentary rocks primarily of calcium carbonate. Limestone is

generally obtained from the calcareous remains of marine or fresh water organisms

embedded in calcareous mud. They change from the soft chalks to hard crystalline

rocks.

2.5.2 Mineral Filler Gradation

Mineral Filler should be graded to ensure that it consists in class filler. It should

be sieve openings with the percentage by weight passing as listed in the table 2.3.

Table 2.3: Gradation for mineral filler

Sieve Openings (mm) Percentage by weight

0.600 100

0.150 90-100

0.075 70-100

Source: PWD 2008 Standard

2.6 FLY ASH

Fly ash is the finely divide residue that from the combustion of pulverized coal

and is transferred from the combustion chamber by exhaust gases. Over 61 million

metric tons (68 million-tons) of fly ash were produced in 2001. (American Coal Ash

Association FHWA-IF-03-01 9; 2003).

Fly ash is produced by coal-fired electric and steam generating plants. Typically,

coal is pulverized and burned out with air into the boiler combustion chamber where it

immediately ignites, generating heat and creating a molten mineral residue. Boiler tubes

extract heat from the boiler, cooling the flue gas and making the molten mineral residue

to harden and form ash. Coarse ash particles, named to as bottom ash or slag, fall to the

backside of the combustion chamber, while the lighter fine ash particles, termed fly ash,

remain suspended in the flue gas. Prior to running through the flue gas, fly ash is

removed from particulate emission control devices, such as electrostatic precipitators or

filter fabric bag houses. (American Coal Ash Association FHWA-IF-03-019; 2003).

Presently, over 20 million metric tons (22 million tons) of fly ash are used

annually in a diversity of technology applications. Typical highway engineering

applications include: Portland cement concrete (PCC), soil and road base stabilization,

flow able fills, grouts, structural fill and asphalt filler. (American Coal Ash Association

FHWA-IF-03-0 19; 2003)..

Fly ash is most ordinarily applied as a Pozzolans in PCC applications. Pozzolans

are siliceous or siliceous and aluminous materials, which in a finely divided form and in

the presence of water, react with calcium hydroxide at ordinary temperatures to produce

cement compounds. (American Coal Ash Association FHWA-IF-03-019; 2003).

The unique spherical shape and particle size distribution of fly ash make it good

mineral filler in hot mix asphalt (HMA) applications and improves the fluidity of flow

able fill and grout. The consistency and abundance of fly ash in many areas present unique Opportunities for use in structural fills and other highway applications. Fly ash

10

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utilization, especially in concrete, has significant environmental benefits including

(American Coal Ash Association FHWA-IF-03-019; 2003).

. Increasing the life of concrete roads and structures by improving

concretedurablity;

. Net reduction in energy use and greenhouse gas and other adverse air

emission when fly ash is used to replace or displace manufactured

cement;

Reduction in the amount of coal combustion • products that must be

disposed in landfills; and

Preservation of other natural resources and materials.

2.6.1 Production of Fly Ash

Fly ash is created from the burning of coal in electric service program or

industrial boilers. There are four basic types of coal-fired boilers such as pulverized coal

(PC), stoker-fired or travelling grate, cyclone, and fluidized-bed combustion (FBC)

boilers. The PC boiler is the most widely utilized, particularly for large electric

generating units. The other boilers are more common in industrial or generation

facilities. Fly ash is caught from the flue gases using electrostatics precipitates or in

filter fabric collectors; it is usually consulted to as burgess. The physical and chemical

features of fly ash vary among combustion methods, coal source and particle shape.

(American Coal Ash Association FHWA-IF-03-019; 2003).

2.6.2 Production of Fly Ash

2.6.2.1 Size and Shape

Fly ash is typically finer than Portland cement and lime. Fly ash consists of silt-

sized particles which are mostly spherical, typically ranging in size 10 and 100 micron

(Figure 2.1). These little glass spheres improve the fluidity and workability of the

admixture Fineness is one of the important properties contributing to its widespread

application in highways.