THE RELATIONSHIP BETWEEN MARSHALL STABILITY, FLOW

THE RELATIONSHIP BETWEEN MARSHALL STABILITY, FLOW AND

RUTTING OF THE NEW MALAYSIAN HOT-MIX ASPHALT MIXTURES

MUKHTAR ELSEDDIG ABUKHETTALA

A project report submitted in partial fulfillment of the

requirements for the award of the degree of

Master of Engineering (Civil - Transportation and Highway)

Faculty of Civil Engineering

Universiti Teknologi Malaysia

NOVEMEBER 2006

iii

“To my beloved father and mother,

my lovely brother and my dearest sisters.

To my brother-in-law (Yousef),

for their eternal love, support and encouragement…”

iv

ACKNOWLEDGEMENT

First and foremost, I would like to express my deep gratitude and most

heartfelt thanks to the Almighty "ALLAH" (SWT) for His Blessing, for lightening up

my heart with the torch of knowledge and for seeing me throughout my lifetime.

With utmost respect and pleasure, I would like to express my sincere thanks

and appreciation to my academic supervisor Dr. Mohd Rosli Bin Hainin, who

continuously guided me throughout every step of my thesis work and generously

shared his time and knowledge with me. I am greatly indebted to him for his

encouragement and incessant help to achieve more than I expected of myself.

My gratitude and deep appreciation go to my co-supervisor, Associate

Professor Dr. Abdul Aziz Bin Chik, for having the patience of a saint whilst I was

conducting my laboratory work and orienting me in the correct research direction.

My special thanks must be extended to technical staff members at the

highway & transportation engineering laboratory at UTM for their collaboration. In

particular, En. Suhaimi, for his steadfast assistance while carrying out my laboratory

work.

I would like to express special great words of thanks to my family, who

tirelessly encouraged and supported me in countless ways to pursue my Master's

Degree. I thank my brother-in-law, Dr.Yousef, for his brotherly love, moral support

and incessantly assist with words of assurance throughout my way. Without their

sacrifices, understanding and endless care, I would not have had the opportunity to

study in Malaysia and I could never have reached where I am today.

Last but not least, Million words of thanks for friends of mine who showed

their concern and support all the way.

vi

ABSTRACT

Hot-mix asphalt (HMA) has reasonably served well in the past. The high tire

pressures and increased wheel loads of traffic moving on roads is primarily

considered as the major cause of increasing the premature rutting of asphalt

pavement. Therefore, it has become necessary to improve HMA mixtures to

withstand the increased stresses. Many road pavement agencies have been using

Marshall Mix Design method for designing HMA mixtures and it is believed that

fundamental changes must be made in the aggregate components of HMA to reduce

rutting to tolerable levels. Properties of Hot-mix asphalt mixtures such as stability,

durability, and resistance to permanent deformation (rutting) can be largely affected

by aggregate gradation. Hence, gradation is considered as the centerpiece property of

aggregate that influences the performance of asphalt pavement. However, other

factors such as field compaction efforts and bitumen content have also some effects

on pavement performance. In Malaysia, rutting has been a continuous problem and it

has become necessary to give more attention to selecting materials that could

minimize this problem. Jabatan Kerja Raya (JKR) has recently set up a new standard

for asphalt mixes that could be rut resistant. In This research, an attempt was made

to evaluate the relationships between Marshall Stability, flow and rut depth of the

New Malaysian Hot-Mix Asphalt mixtures using five different asphalt mixtures,

which are ACW10, ACW14, ACB28, SMA14 and SMA20. Stability and flow values

of all mixes had been determined at the optimum bitumen content obtained from

Marshall Design Method. Rut depth has been evaluated using the Three-Wheel

immersion tracking Machine. Results have revealed that there is no good correlation

between Stability and flow of the new Malaysian HMA mixtures. It was concluded

that Stability, Flow and Stiffness can not be used to predict Rutting potential of the

New Malaysia hot-mix asphalt mixtures.

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ABSTRAKT

Campuran panas berasfalt (HMA) telah terbukti untuk berfungsi dengan baik.

Tekanan tayar yang tinggi dan peningkatan pembebanan lalulintas dikatakan sebagai

sebab utama untuk meningkatkan aluran permatang pada turapan berasfalt. Olen itu,

ianya menjadi keperluan untuk memperbaik campuran HMA untuk menangung

peninkatan tekanan. Banyak agensi jalan yang mengunakan kaedah rekabentuk

campuran Marshall dalam mereka bentukkan campuran HMA dan dipercayai

perubahan besar mestilah dibuat terhadap komponen agregat HMA untuk

mangurangkan aluran ke tahap yang bolah diterima.Siafat-sifat campuran panas

berasfalt seperti kestabilan, ketahanlasakan, dan rintangan terhadap ubahbentuk

kekal (akuran) bole dipegaruhi oleh gradasi agregat.dengan itu gradasi

dipertimbangkan sebagai sifat utama agregat yang mempengaruhi pelaksanaan

turapan berasfalt. Walau bagaimanapun, faktor-faktor lain seperti usaha

permandaptdan kandungan bitumen juga mempunyai kesan terhadap perlaksanaan

turapan. Di Malaysia, aluran yang sememangnya telah menjadi masalah harualah

diberi perhatian yang lebih dalam pemilihan bahan untuk mengurangkan masalah ini.

Baru-baru ini, Jabatan Kerja Raya (JKR) telah megemukakan piawaian yangbaru

untuk campuran-campuran asfalt yang boleh merintangi aluran. Dalam kajian ini,

satu percubaan telah dilakukan untuk menilai hubungan diantara kestabilan Marshall,

aliran, dan kedalaman aluran campuran berasfalt panas Malaysia yang baru dengan

mengunakan lime campuran berasfalt yang berbeza, iaitu ACW10, ACW14,

CAW28, SMA14, dan SMA20. nilai-nilai kestabilan dan aliran untuk kesemua

campuran telah ditentukan pada kandungan bitumen optimum yang diperoleh

daripada kaedah rekabentuk Marshall. Kedalaman aluran telah dinilai dengan

menggunakan mesin jejak tiga roda. Keputusan menunjukkan bahawa tiada korelasi

yang baik diantara kestabilan dan aliran bagio campuran HMA Malaysia yang baru.

Boleh disimpulkan bahawa kestabilan, aliran, dan kekukuhan tidak boleh digunakan

untuk meramalkan potensi aluran bagi campuran panas berasfalt Malaysia yang baru.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAKT vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xii

LIST OF APPENDIXES xiv

I INTRODUCTION

1.1 Aggregate Gradation 1

1.2 Permanent Deformation Resistance 2

1.3 Problem Statement 4

1.4 Objective 4

1.5 Scope of the Study 4

II LITERATURE REVIEW

2.1 General Introduction 6 2.2 Description Of rutting Distress Mechanism 7

2.3 Rutting Severity Levels 8

2.4 Rutting Evaluation Tests 11

2.4.1 Hamburg Wheel Tracking Machine 11

2.4.2 Asphalt Pavement Analyzer 14

2.4.3 Three-Wheel Immersion Tracking Machine 16

viii

III METHODOLOGY

3.1 Introduction 17

3.2 Laboratory Tests Procedure 21

3.3 Aggregate Preparation (Sieve Analysis Of Coarse

And Fine Aggregate (ASTM C136-84A 23

3.4 Determination Of Aggregate Specific Gravity 26

3.4.1 Determination Of Coarse Aggregate

Specific Gravity 26

3.4.2 Determination Of fine Aggregate Specific

Gravity 27

3.5 Marshall Mix Design (ASTM D1559) 29

3.5.1 Mix Design Preparation 30

3.5.2 Theoretical Maximum Specific Gravity And

Density of Bituminous Paving Mixtures 33

3.5.3 Bulk Specific Gravity Of Compacted

Bituminous Mixtures Using Saturated

Surface-Dry Specimens (ASTM D2726)

36

3.5.4 Resistance To Plastic Flow of Bituminous

Mixtures Using Marshall Apparatus (ASTM

D1559)

39

3.5.5 Volumetric properties of compacted

mixtures 43

3.6 Evaluating of Rutting Potential Using the Three-

Wheel Immersion Tracking Machine 45

3.6.1 Determination of Number of Roller Passes 46

3.6.2 Procedure of the Three-Wheel Immersion

Tracking tests 48

3.7 Specification 49

3.8 Data analysis 49

IV RESEARCH RESULTS AND ANALYSIS

4.1 Introduction 51

4.2 Aggregate gradation 51

ix

4.3 Sieve analysis 57

4.3.1 Dry sieve analysis 57

4.3.2 Washed sieve analysis 57

4.4 Bulk specific gravity of aggregate 57

4.4.1 Bulk specific gravity of coarse aggregate 58

4.4.2 Bulk specific gravity of fine aggregate 58

4.4.3 Mineral filler specific gravity 59

4.4.4 Bulk specific gravity of total aggregate

( S.G blend) 59

4.5 Specific gravity of Bitumen 60

4.6 Maximum specific gravity of paving mixtures 60

4.7 Effective specific gravity of aggregate 61

4.8 Volumetric properties analysis 62

4.8.1 Voids in total mix (VTM) 62

4.8.2 Voids in mineral aggregate (VMA) 63

4.8.3 Voids filled with bitumen (VFB) 64

4.9 The optimum bitumen content 64

4.10 Marshall Mix Design results of different mixtures at

the optimum bitumen content 65

4.11 Evaluation of Rut depth using the Three-Wheel

immersion tracking machine 66

4.11.1 Determination of number of roller passes 66

4.11.2 Conduction the Three-Wheel immersion

tracking test 68

4.12 Discussion 72

V CONCLUSION AND ECOMMENDATION 74

REFERENCES 75-77

APPENDIXES A - C 78-107

x

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Possible rutting causes and probable treatments 9

3.1 Gradation Limit for Asphaltic Concrete (ACW10) 18

3.2 Gradation Limit for Asphaltic Concrete (ACW14) 18

3.3 Gradation Limit for Asphaltic Concrete (ACB28) 19

3.4 Gradation Limit of combined aggregate (SMA14,

SMA20) 19

3.5 Design Bitumen Content 20

3.6 Test and Analyses Parameter for Asphaltic Concrete

(JKR/SPJ/rev2005) 20

3.7 Minimum sample size requirement for coarse

aggregate specific gravity 26

3.8 Minimum sample size requirement for Theoretical

Maximum Density (ASTM D2041) 34

3.9 Stability Correlation Ratios 42

3.10 SMA Mix requirements (JKR/SPJ/rev2005) 45

3.11 The suggested form of the obtained results 50

4.1.1 Aggregate gradation for ACW10 52

4.1.2 Aggregate gradation for ACW14 53

4.1.3 Aggregate gradation for ACB28 54

4.1.4 Aggregate gradation for SMA14 55

4.1.5 Aggregate gradation for SMA20 56

4.2 Bulk specific gravity of coarse aggregate for different

mixtures 58

4.3 Bulk specific gravity of fine aggregate for different

mixtures 59

xi

4.4 Bulk specific gravity of Blend for different mixtures 59

4.5 Theoretical Maximum density of all used mixtures 60

4.6 Theoretical Maximum density at each asphalt

Content for each asphaltic mixture 61

4.7 Effective Specific Gravity of each mixture used in this

research 62

4.8 Percentage of VTM for different mixtures 62 4.9 Percentage of VMA for different mixtures 63 4.10 Percentage of VFB for different mixtures 64 4.11 The Optimum Bitumen Content of asphaltic mixes 64

4.12 Marshall Mix design results for different mixtures 65

4.13 Results of determining required number of roller

passes 67

4.14 Results of the Three-Wheel immersion tracking

machine 68

4.15 Stability, Flow, Stiffness and Rut depth of various

asphaltic mixtures 69

xii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Rutting severity levels as classified by JKR 8

2.2 Types of Asphalt pavement rutting 9

2.3 Asphalt pavement rutting due to plastic movement of the asphalt mix Under heavy loads.

10

2.4 Hamburg Wheel Rut Tester in operation. 12

2.5 Asphalt samples submerged in water prepared for the HWRT wet test.

12

2.6 Asphalt cylindrical samples after application Of 20,000 Wheel passes (HWRT)

12

2.7 Typical Hamburg Wheel Tracker Test Results 13

2.8 Testing of cylindrical and beam hot-mix asphalt samples in the APA.

14

3.1 Laboratory Test Flow chart 22

3.2 Sieves from 75μm to 37.5mm are placed on the mechanical shaker

24

3.3 Washing of Aggregate before sieving process 25

3.4 Weighing Aggregate during a Sieve Analysis 25

3.5 Aggregates sieved and separated according to particle size

25

3.6 Determination of fine aggregate specific gravity 29

3.7 The specimens that have been prepared by Marshall Mix Design

32

3.8 The ASTM D 2041 test apparatus 33

3.9 Steps of Bulk Specific Gravity Test 38

3.10 Compression Testing Machine 39

3.11 Speicemen are being immersion in water bath 40

3.12 Lubricating of the guide and its rods prior to testing 40

3.13 Breaking head is placed on a sample 41

3.14 Sample is placed in Marshall stability machine 41

xiii

3.15 Decanting of the sample into the mould 46

3.16 Sample after compacting ready to be tested 47

3.17 The Three-Wheel immersion Tracking Machine 49

4.1 (a) Gradation limits and mix design curve for ACW10 52

4.1 (b) Gradation limits and mix design curve for ACW14 53

4.1 (c) Gradation limits and mix design curve for ACB28 54

4.1 (d) Gradation limits and mix design curve for SMA14 55

4.1 (e) Gradation limits and mix design curve for SMA20 56

4.2 Number of roller passes versus %VTM 68

4.3 Roller Passes versus Rut Depth results 69

4.4 (a) Stability versus Rut Depth 70

4.4 (b) Flow versus Rut Depth 70

4.4 (c) Flow versus Stability 71

4.4 (d) Stiffness versus Rut Depth 71

xiv

LIST OF APPENDIXES

APPENDIX TITLE PAGE

A 1. Aggregate gradation 79-81

2. Dry & washed-sieve analysis results 82-91

3. Percentage of bitumen contents & Required weight

of asphalt for different mixtures 92

B Bulk Specific Gravity of coarse and fine Aggregates 94-98

C Maximum Specific Gravity of Loose Mixtures 99-101

D Marshall Mix Design results 102-107

CHAPTER I

INTRODUCTION

1.1 Aggregate gradation

Aggregate gradation is the distribution of particle sizes expressed as a

percentage of the total weight. The gradation as a percent of the total volume is of

most importance, but expressing gradation as a percent by weight is much easier and

is a standard practice. Gradation is determined by sieve analysis, sieves are stacked

from the largest openings on the top to the smallest opening on the bottom, and a pan

is placed at the bottom of the stack, by passing the material through a series of sieves

and weighing the material retained on each sieve, gradation can be determined. The

gradation of an aggregate is normally expressed as total percent passing various sieve

sizes [1].

Some properties of Hot-mix asphalt mixture such as stiffness, stability,

durability, fatigue resistance and resistance to permanent deformation, can be largely

affected by aggregate gradation. Therefore, gradation is considered the most

important property of aggregate that influences the performance of asphalt

pavements [1].

Stability of HMA is important aspect that affects the performance in the field.

It can be increased by increasing the internal friction between aggregates and

improving the shear resistance. Increasing of mix stability through increase anti-

particle contact and reduce voids in the mineral aggregate may result from gradation

2

that provide a maximum density. However, there must be sufficient air void spaces

to permit enough asphalt cement to be incorporated to ensure durability, while still

leaving some air space in the mixture to avoid bleeding and rutting [1].

Improper and unsuitable aggregate gradation causes a lot of trouble to the

performance of HMA. One of the problems caused by poor aggregates gradation is

tender mixes, which rut easily under traffic load and cannot be compacted in the

normal manner because of their slow ability to develop sufficient stability to

withstand the weight of the compaction equipment [1].

In recent years, there has been an increase in the use of large stone mixes to

minimize rutting potential of HMA. Using of large stone mixes increases the volume

concentration of the aggregate and contributes to a reduction of both asphalt content

and cost of the mix. However, the use of a maximum aggregate size greater than

(1inch) often results in a harsh mixes that tend to segregate during construction [1].

In addition, using of the Stone Mastic Asphalt (SMA) has been widely used

in recent years due to it is excellent rutting resistance on high volume roads. The

high resistance to rutting is due to high proportion of coarse aggregate in SMA

mixtures, which represents about 70-80% of the mix and produces stone-to-stone

contact. SMA mixture has an ability to improve stability and increase durability at

the same time. The stability in SMA is obtained through internal friction in the self-

supporting stone skeleton.

1.2 Permanent deformation resistance

Resistance to permanent deformation is one objective should be kept in mind

when designing HMA. The mix should not distort (rut) or displace when subjected

to traffic load. The resistance to permanent deformation (rutting) becomes critical

during hot weather months when the viscosity of the asphalt binder is low and the

traffic load is primary carried by the mineral aggregate structure. Resistance to

permanent deformation is controlled by selecting the quality aggregate with proper

3

gradation and selection the asphalt content that is enough but not too much to

provide adequate air voids exist in the mix [1].

The mix proportions for a properly compacted asphalt concrete paving

mixtures are determined in the laboratory during mix design testing. The ability of a

properly proportioned asphalt paving mix to resist potentially damaged effects of the

asphalt binder stripping from the aggregate particles is also routinely evaluated in the

laboratory. To perform properly in the field, a well-designed asphalt paving mixture

must be placed within the proper temperature range and must be adequately

compacted. HMA mixtures should be evaluated for the following properties [5]:

• Stability: which is the load that a well-compacted paving mixture can accept

and withstand before failure. Sufficient mix stability is required to satisfy the

demands of traffic without rutting or bleeding problems [5].

• Flow: which is the maximum deformation measured at the instance of failure

under the load applied. The ratio of Marshall Stability to flow approximates

the mix's load deformation characteristics and therefore indicates the material

resistance to permanent deformation [5].

The asphalt concrete mix design process is conducted to determine an

aggregate gradation that meets the requirements of the specifications in terms of

voids in mineral aggregate(VMA), air voids content (voids in total mix VTM) and

density. Any changes that occur in the gradation can alter the properties of the mix.

The degree of change in the mix properties is the function of the change in gradation

of the aggregate. If that change is significant, the potential for an increase in the

permanent deformation of the mix can also be significant [2].

4

1.3 Problem statement

The high increase in number of vehicles and heavy traffic volumes on the

roads at an alarming proportion consequently increases the tire pressures and

produces heavier axle loads imposed on pavement structure. Hence, there has

become a need to enhance asphalt pavement mixtures that may prone to rutting, to

withstand the increase of loading, mitigate adverse affects on pavement performance

and reduce occurrence of premature rutting. Gradation is a property that needs a

careful consideration due to its effect on performance of HMA mixtures. In addition,

mix properties, such as air voids, stability and resistance to permanent deformation

are strongly affected by the proper gradation of aggregates.

1.4 Objective

The objective of study is:

• Evaluating the relationships between Marshall Stability, flow and rutting

potential of the New Malaysian HMA mixtures.

1.5 Scope of the Study

The scope of this study concentrates on preparing asphalt concrete mixes

based on the new Malaysian hot-mix design mixtures using Marshall Mix design

method. The optimum bitumen content of all mixes will be obtained and the stability

and flow values at the obtained OBC will be determined. In addition, rutting

potential (rut depth) of different mixtures will be evaluated by means of the Three-

Wheel immersion-tracking machine.

Asphaltic concrete mixtures that will be used in this research include; Asphalt

concrete for wearing coarse (ACW10 and ACW14), Asphalt concrete for binder

5

coarse ACB28, and Stone Mastic Asphalt (SMA14 and SMA20) in accordance with

the new aggregate gradation proposed by JKR.

Samples will be compacted with two different levels of compaction, which

are; 75 blows / face for asphaltic concrete for wearing and binder course mixtures

and 50 blows / face for Stone Mastic Asphalt mixtures.

CHAPTER II

LITRATURE REVIEW

2.1 General Introduction

Marshall Stability is generally a measure of mass viscosity of the aggregate-

asphalt cement mixture. It is significantly affected by the angle of internal friction of

aggregate and the viscosity of asphalt cement at 60°C (140°F). This stability is

defined as the maximum load (that the specimen can withstand) carried by a

compacted specimen tested at 60°C (140°F) at a loading rate of 2 inches/minute

(50.8mm/minute).

The main purpose of Marshall Stability test is to measure the strength of an

asphalt mixture that has been compacted to a standard laboratory compactive effort.

One of the easiest ways to increase the stability of an aggregate mixture is by

changing to higher viscosity grade of asphalt cement [1]. Anything that increases the

viscosity of the asphalt cement increases the Marshall stability. The stability of a

mixture in the field is affected by some parameters, such as the ambient temperature,

aggregate gradation, type of loading, rate of loading, tire contact pressure and

numerous mixture properties. The primary use of Marshall Stability is in evaluating

the change in stability with increasing asphalt content to aid in selection the optimum

asphalt content [1].

The flow is equal to the vertical deformation of the sample (measured from

the start of loading to the point at which stability begins to decrease). It is measured

7

at the same time as Marshall Stability. High flow values indicate a plastic mix that

will experience deformation under traffic, whereas low flow values indicate a mix

with percent of air voids higher than the normal voids and insufficient asphalt [1].

The flow value or flow index is the total vertical deformation of the specimen

at the maximum load. Marshall Stiffness which is Marshall Stability divided by flow

is a term sometimes used to characterize asphalt mixture. A higher value of stability

divided by flow indicates a stiffer mixture and hence, indicates the mixture is likely

more resistance to permanent deformation.

2.2 Description of rutting distress mechanism

Rutting of asphalt concrete pavement is the permanent deformation of any of

the layers in the structural system. It is considered as one of the most common and

destructive pavement distresses. There are five areas of distress that affect

performance of Hot-Mix asphalt which are: fatigue cracking, rutting, thermal

cracking, friction, and moisture susceptibility. All of these distresses can result in

loss of performance but rutting is the one distress that is most likely to be a sudden

failure as a result of unsatisfactory hot mix asphalt. Other distresses are typically

long-term failures that show up after a few years of traffic.

The rutting distress is recognized as a surface depression in the wheel path.

Ruts are particularly evident after a rain when wheel paths are filled with water.

When rutting path filled with water, it can cause vehicle hydroplaning, which is

considered hazardous because ruts tend to pull a vehicle towards the rut path as it is

steered across the rut path.

8

2.3 Rutting severity levels

Rutting severity has been classified according to JKR specification into three

different levels, which are low, moderate and high level. The following is a brief

explanation of the three different levels respectively.

• Low severity level: Where rut depths of less than 12mm (measured under

1.2 m straight edge) [4].

• Moderate severity level: Where rut depths of between 12mm and 25mm

(may include slight longitudinal cracks) [4].

• High severity level: Rut depths of greater than 25mm (may include

multiple longitudinal or crocodile cracks) [4].

a) Low severity: Rut depth <12mm b) Moderate severity: Rut depth

between12 mm to 25 mm

c) High severity: Rut depth >25mm

Figure 2.1: Rutting severity levels as classified by JKR

9

In addition, JKR has identified some possible causes and probable treatments

of rutting .The following table illustrates some of them.

Table 2.1: Possible rutting causes and probable treatments

No. Possible Causes Probable Treatments

1. Inadequate pavement thickness. Strengthen overlay or reconstruction

2. Inadequate compaction of layers Reconstruction.

3. Unstable bituminous mixes. Use stiffer mix.

4. Overstressed sub grade, which

deforms permanently.

Reconstruction.

5. Excess bitumen in the mix. Proper selection of asphalt content for

the mix for the purpose

Asphalt pavement rutting can be caused by insufficient pavement structural

support allowing excessive stress to be transferred to the sub grade (structural

rutting); however, the most common type of rutting is asphalt ‘stability’ rutting

caused by the plastic movement of asphalt mix under heavy, often slow moving

loading. The deformation is exaggerated during periods of high ambient temperature.

An increase in the stiffness of asphalt concrete mixture at a given temperature causes

an increase in the rutting resistance of the pavement. To the extent that asphalt

influences mix stiffness, an increase of the viscosity of the asphalt cement at the

same temperature can produce a mix with improved rutting resistance.

Over densification

Plastic flow

Figure 2.2: Types of Asphalt pavement rutting (19)

10

Figure 2.3: Asphalt pavement rutting due to plastic movement of the asphalt mix Under heavy loads. (18)

Rutting in pavement usually develops gradually with increasing numbers of

load applications. It typically appears as longitudinal depressions in the wheel paths

sometimes accompanied by small upheavals to the sides. It is generally caused by a

combination of densification (decrease in volume and, hence, increase in density)

and shear deformation and can occur in any one or more of the HMA layers as well

as in the unbound materials underneath the HMA. Eisenmann and Hilmer (6) also

found that rutting is mainly caused by deformation flow rather than volume change.

Predicting performance of HMA is very difficult due to the complexity of

HMA, the complexity of the underlying unbound layers and varying environmental

conditions. Presently, there are no specific methods being used nationally to design

and control HMA to control rutting.

The cost of asphalt pavement rutting repairs can be very high and disruptive

on traffic operations. A reliable, accelerated laboratory performance test to evaluate

rutting resistance of asphalt mixes is considered necessary. Several laboratory

methods are in use for test for rutting characteristics of asphalt concrete mixture.

11

2.4 Rutting Evaluation Tests

Test that have the potential for predicting rutting resistance include uniaxial

static and repeated load tests, triaxial static and repeated load tests, and simulative

tests. The simulative tests primarily include wheel-tracking tests. The Asphalt

Pavement Analyzer (APA), Hamburg Wheel Rut Tester (HWRT) and French

Laboratory Rutting Tester (FLRT) are considered to provide reasonable results and

good correlation with field performance. These rut testers have been used in Canada

and the United States for mix designs, pavement evaluation, assessment of new

materials, quality control, and pavement failure investigation [8].

2.4.1 Hamburg Wheel-Tracking Machine The HWTD, It is used to evaluate rutting and stripping. Tests within the

HWTD are conducted on a slab that is 260 mm wide, 320 mm long, and typically 40

mm thick (10.2 in x 12.6 in x 1.6 in). These slabs are normally compacted to 7±1

percent air voids.

Testing in the HWTD is conducted under water at temperatures ranging from

25°C to 70°C (77°F to 158°F), with 50°C (122°F) being the most common used

temperature. Loading of samples in the HWTD is accomplished by applying a 705-N

(158-lb) force onto a 47-mm-wide steel wheel (or 50-mm-wide rubber wheel). The

steel wheel is then tracked back and forth over the slab sample. Two samples can be

tested simultaneously in one HWRT run. Some researchers in Europe consider that

the use of the steel wheel is too severe and may cause excessive damage to asphalt

samples. There is more experience with wheel tracking tests than with any other type

of test to predict rutting. Other tests have promise but more work is needed to

finalize details before they are utilized for mix control (research is underway to do

this) [13].

Test samples are loaded for 20,000 passes or until 20 mm of deformation

occur. The travel speed of the wheel is approximately 340 mm per second. Colorado

12

DOT recommends maximum allowable rut depth (figure 2.6) of 4.0 mm at 10,000

wheel passes and 10 mm at 20,000 wheel passes while the Texas DOT specification

requires that the rut depth be less than 12.0 mm at 20,000 passes [9].

Figure 2.4: Hamburg Wheel Rut Tester in operation.

Figure 2.5: Asphalt samples submerged in water prepared for the HWRT wet test.

Figure2.6: Asphalt cylindrical samples after Application of 20,000 Wheel passes (HWRT).

13

As shown in Figure 2.7, results obtained from the HWTD consist of rut

depth, creep slope, stripping inflection point, and stripping slope. The creep slope is

the inverse of the deformation rate within the linear region of the deformation curve

after post compaction and prior to stripping (if stripping occurs). The stripping slope

is the inverse of the deformation rate within the linear region of the deformation

curve, after the onset of stripping. The stripping inflection point is the number of

wheel passes corresponding to the intersection of the creep slope and the stripping

slope. This value is used to estimate the relative resistance of the HMA sample to

moisture induced damage [10].

Figure 2.7: Typical Hamburg Wheel Tracker Test Results (10)

Numerous studies have been conducted to compare results of Loaded Wheel

Tester (LWT) to the actual field performance. A joint study by the FHWA and

Virginia Transportation Research Council evaluated the ability of three LWTs to

predict rutting performance. The relationship between LWT and field rutting for all

three LWTs was strong. The HWTD had the highest correlation (R²=0.91), followed

by the APA (R²=0.90) and FRT (R²=0.83). From that study, it was concluded that

results obtained from the wheel tracking devices seem to correlate reasonably well to

actual field performance when the in-service loading and environmental conditions

of that location are considered [11].

14

2.4.2 Asphalt Pavement Analyzer

The Asphalt Pavement Analyzer (APA), shown in Figure 8 below, was

developed in 1995. The APA has been used to evaluate the rutting, fatigue, and

moisture resistance of HMA mixtures. It features controllable wheel load and contact

pressure adjustable temperature inside the test chamber. In evaluating rutting

potential using the APA, a wheel is loaded onto a pressurized linear hose and tracked

back and forth over a testing sample to induce rutting. Most tests are typically carried

out to 8,000 cycles (one cycle is defined as the backward and forward movement of

the wheel over samples) and samples can be tested while submerged in water.

Figure 2.8: Testing of cylindrical and beam hot-mix asphalt samples in the APA.

Testing specimens for the APA can be either beam or cylindrical. Beams are

most often compacted to 7 % air voids, while cylindrical samples have been

fabricated to both 4 % and 7 % air voids. Beams or cylindrical samples are placed in

a test chamber. The amount of permanent deformation (rut depth) under repetitive

load is monitored by a computer and display in a screen. Test temperatures for the

APA have ranged from 40.6°C to 64°C (105°F to 147°F). The most recent work has

15

been conducted at or slightly above expected high pavement temperatures. Wheel

load and hose pressure are 445 N and 690 kPa (100 lb and 100 psi), respectively.

Rut depth is measured with an electronic dial indicator. Some States in the

USA use a maximum deformation of 5.0 mm in the APA as the pass-fail criterion for

mixes designed to be used on interstate highways [7].

After the APA came on the market, the Florida Department of Transportation

conducted a study using three mixes of known field performance. The three mixes of

were tested in the APA. Within this study, beams and cylinders were both tested.

Results showed that both sample types ranked the mixes similar to the field

performance data. Therefore, the study has concluded that the APA had the

capability to rank mixes according to their rutting potential [12].

Aggregate gradation is an important factor that influences the permanent

deformation potential of HMA. One common way to characterizing aggregate

gradation is by making a gradation plot on a 0.45 power chart, which also contains a

maximum density line. It is believed that gradation passing through the restricted

zone can have low stability. Experience shows that stiff binder courses with bigger

aggregates have less rutting potential compared to relatively more flexible wearing

courses with fine aggregate and higher binder content. Statistical analyses of APA rut

depth obtained from tested mixes with different aggregate gradation indicates a

significant difference between rut depths of mixes gradation passing above, through

and below the Superpave restricted zone [14].

A study was conducted to evaluate affects of aggregate gradation on

performance of asphalt mixture in university of Kansas in 1999. Two mixes were

used in the study, one of coarse gradation and the other of fine gradation. The two

mixes were evaluated for air-void, permanent deformation and gradation. Then they

were coarsened to simulate the effects of production variability and segregation and

test repeated. Coarsening of mixtures led to an increase in VTM, VMA that

decreases the stability of mixture. Fine mixture had less rutting (5mm) than the

coarse mixture (8.9m) using APA. Results from this study was indicated that fine

16

aggregate was stronger that coarse aggregate as measured by APA to evaluate rutting

potential [15].

Another study was carried out to evaluate rutting potential of pavement mixes

using 4-in and 6-in samples. From this study, it was concluded that the amount of

voids in total mix VTM is likely the most important property of asphalt mixtures that

relates to rutting and plastic flow of the asphalt mixtures is likely to begin once the

VTM are reduced to approximately 3%.

The study draw a conclusion that there is a good possibility that the voids

level decreases under compaction to some point at which rutting begins to occur and

at which time the voids level begins to increase due to shoving of the mixture. In

addition, mixes having flow values above 10 tended to have higher amount of

rutting. Coring of 4-in and 6-in samples from the site indicated that most observed

rutting occurred in layers, which contained fine aggregate gradation and high asphalt

content [16].

2.4.3 Three-Wheel Immersion Tracking Machine

The wheel tracking tests have been largely used for evaluating of rutting

behavior. The Transport and Road Research Laboratory of the United Kingdom

adopted the Three Wheels Immersion Tracking Machine in 1951. The main purpose

of this machine is to evaluate pavement-rutting resistance using moving wheels that

simulate the actual moving loads of traffic.

CHAPTER III

METHODOLOGY

3.1 Introduction

The main aim of this project is to evaluate the relationships between Marshall

Stability, flow and rutting potential of the new Malaysian Hot-Mix Asphalt mixtures.

Rutting potential will be evaluated using the Three-Wheels immersion Tracking

Machine which is available in the highway and transportation laboratory at Universiti

Teknologi Malaysia.

Samples will be prepared and tested according to the JKR/SPJ/rev2005 as a

guide to attain that the laboratory works and materials fulfill the Malaysian Road

works circumstances. Five different asphaltic mixtures will be used throughout the

laboratory work namely; Asphalt concrete for wearing course ACW10 and ACW14,

Asphalt concrete for binder course ACB28 and Stone Mastic Asphalt (SMA14 and

SMA20). Tables 3.1, 3.2, 3.3 and 3.4 below show the appropriate envelopes for the

new aggregate gradations that have been introduced recently by JKR, which will be

used in this project.

All samples will be prepared based on Marshall Laboratory compaction

method and by using of 100mm mould size. For each laboratory design mix

gradation, three specimens will be prepared for each bitumen content within the

range given in Table 3.5 below at increments of 0.5 percent in accordance with

ASTM D1559 using 75-blows/face compaction standard (heavy traffic) for (ACW10,

ACW14, ACB28) mixtures, and 50-blows/face for (SAM14, SMA20) mixtures.

18

Once Specimens have been compacted using Marshall Hammer, they will be tested

for stability and flow.

Table 3.1: Gradation Limit for Asphaltic Concrete (ACW10)

Mix Type Wearing Course

B.S Sieve Size,mm % Passing By Weight

28.0

20.0

14.0

10.0

5.0

3.35

1.18

0.425

0.150

0.075

PAN

-

-

100

90-100

58-72

48-64

22-40

12-26

6-14

4-8

-

Table 3.2: Gradation Limit for Asphaltic Concrete (ACW14)

Mix Type Wearing Course


28.0

20.0

14.0

10.0

5.0

3.35

1.18

0.425

0.150

0.075

PAN

-

100

90-100

76-86

50-62

40-54

18-34

12-24

6-14

4-8

-

19

Table 3.3: Gradation Limit for Asphaltic Concrete (ACB28)

Mix Type Binder Course


28.0

20.0

14.0

10.0

5.0

3.35

1.18

0.425

0.150

0.075

PAN

100

72-90

58-76

48-64

30-46

24-40

14-28

8-20

4-10

3-7

-

Table 3.4: Gradation Limit of combined aggregate (SMA14, SMA20)

ASTM Sieves Percentage by weight Passing Sieve

Sieve Size, mm SMA14 SMA20

19

12.5

9.5

4.75

2.36

0.600

0.300

0.075

PAN

100

100

72-83

25-38

16-24

12-16

12-15

8-10

-

100

85-95

65-75

20-28

16-24

12-16

12-15

8-10

-

After obtaining the optimum bitumen content, two samples will be prepared

for verification and identifying stability and flow values using the optimum bitumen

content .Thereafter, two beams will also be prepared using the same bitumen

content to carry out rutting potential test using the Three-Wheel immersion tracking

machine.

20

The design bitumen contents for the design process of all mixtures will be as

stated in JKR's specifications that are in the in the appropriate range given in Table

3.5.

Table 3.5: Design Bitumen Content

ACW10 - Wearing coarse

ACW14 - Wearing coarse

ACB28 - Binder coarse

SMA14, SMA20 – Stone Mastic Asphalt

5.0-7.0%

4.0-6.0%

3.5-5.5%

5.0-7.0%

In addition, results obtained from the laboratory work will be compared with

JKR/SPJ/rev2005 requirements as given in Table 3.6 below.

Table 3.6: Test and Analyses Parameter for Asphaltic Concrete (JKR/SPJ/rev2005)

Parameter Wearing Course

Stability S

Flow F

Stiffness S/F

Air voids in mix VTM

Voids in aggregates filled with bitumen VFB

>8000N

2.0-4.0mm

>2000N/mm

3.0-5.0%

70-80%

Bituminous binder of asphaltic concrete for wearing and binder coarse

(ACW10, ACW14 and ACB28) shall be a bitumen of penetration grade 80-100,

which conforms to MS 124 .Whereas the bituminous binder to be used with Stone

Mastic Asphalt (SMA14 and SMA20) shall be of performance grade PG76 or higher

in compliance with AASHTO Standard M320-02.

21

3.2 Laboratory Test Procedure

The laboratory tests are divided into several stages begin with the aggregates

preparation. The gradation of aggregates is used to design the Marshall mixes

samples. Firstly, sieve analysis will be carried out to separate aggregate into different

sizes. Then specific gravity for coarse and fine aggregate will be determined.

Washed-sieve analysis will be done to determine the percentage of dust and silt-clay

material in order to check the need for the filler material. Thereafter, Marshall Test is

conducted to determine the optimum bitumen content (OBC) for each mix type. The

value of the OBC is important for designing the mixes to indicate other mix

performance tests. The value of the OBC will be used to prepare two samples and

two beams to determine the stability and flow of Marshall Test and to evaluate the

rutting potential using the OBC. Figure 3.1 below shows the laboratory test flow.

22

Dry sieve analysis to divide aggregate into different sizes

Washed sieve analysis to determine percentage of dust & silt-clay material

Aggregate blending to obtain the desired gradation

Determination of specific gravity for coarse & fine aggregates

Preparing of mixtures (ACW10, ACW14, ACW28, SMA14, SMA20)

Obtaining of the Maximum Theoretical Specific Gravity

Determination of bulk specific gravity of Marshall compacted mixtures

Volumetric properties analysis

Resistance to Plastic Flow of the Marshall compacted Mixtures

Evaluating of rutting depth using the Wheel Track machine.

Results and analysis

Figure 3.1: Laboratory Test Flow chart

23

3.3 Aggregate preparation (Sieve analysis of Coarse and Fine Aggregate

ASTM C136-84A)

This method is used to determine the aggregate gradation which is proposed

for the project. The results are then used to determine the compliance of the particles

size distribution with the applicable specification requirements and to provide

necessary data to control the production of various aggregate sizes and mixture

containing aggregates. Standard procedure for a dry-sieve analysis is given in ASTM

C136 and for a washed-sieve analysis for determine the amount of material passing

the No 200 (0.075mm) sieve the procedure is given in ASTM C117.The dry method

is faster and is often used to estimate the actual gradation .

The materials which will be used for this study such as aggregates must be

dried an overnight in an oven for at least one day. This procedure is to ensure the

moisture and impurities in aggregate have been removed. Then some portion of

aggregate will be taken as a sample to determine the specific gravity.

The remaining aggregates will be separated into single sizes using sieving

machine. Aggregate retained on each sieve then collected and stored in large

containers or bins. The container will be marked with the sieve size to avoid any

confusing between the aggregate sizes.

A) Scope:

The test is performed to determine the particles size distribution of coarse and

fine aggregates.

B) Apparatuses:

i. Balances;

ii. Sieves;

iii. Mechanical sieve shaker;

iv. Oven.

24

C) Procedure:

i. Aggregates to be used in the blend must be dried to a constant

weight in an oven at a temperature of 110±5°C;

ii. Suitable sieve sizes are selected and nested in order of decreasing

size of opening from the top to the bottom;

iii. Sample is then placed on the top the sieves .Shaking process using

Mechanical Sieve Shaker is then started and continued to agitate

the stacked sieves for a sufficient period of time (normally for

about 3 minutes);

iv. Sieving process is continued until there is no residue on an

individual sieve will pass the sieve using a continues hand sieving;

Figure 3.2: Sieves from 75μm to 37.5mm are placed on the mechanical shaker

v. The quantity of the material on a given sieve is limited so that all

particles have an opportunity to reach the sieve opening during

the sieving operation;

25

Figure 3.3: Washing of Aggregate before sieving process

Figure 3.4: Weighing Aggregate during a Sieve Analysis

Figure 3.5: Aggregates sieved and separated According to particle size.

26

3.4 Determination of aggregate specific gravity

The specific gravity of an aggregate is useful in making weight-volume

conversions and in calculating voids content in a compacted HMA samples. Specific

gravity for both types of aggregate (coarse and fine) will be determined.

3.4.1 Determination of coarse aggregate specific gravity

A) Apparatuses:

i. Balance, which should be accurate to 0.5g of the sample weight;

ii. Sample container;

iii. Water tank;

iv. 4.75mm sieve size.

B) Procedure:

i. Weigh the aggregate and wash it to clean it from the dust;

ii. The minimum weight of tested sample should be as shown below:

Table 3.7: Minimum sample size requirement for coarse aggregate specific gravity

test

Nominal Maximum Aggregate Size Weight of sample

12.5 mm 2.0 kg

19.0 mm 3.0 kg

25.0 mm 4.0 kg

37.5 mm 5.0 kg

27

iii. Soak aggregates in water for 24 hours;

iv. After 24 hours, aggregates are placed into a basket in water path

and its weight is recorded while submerging in water for 3

minutes. This mass is recorded as A;

v. Dry the aggregate with a damp towel until it is saturated surface

dry and weigh it again. The mass of a saturated dry surface is

recorded as B;

vi. Dry the sample in an oven for 24 hours at 110±5°C;

vii. Cool the sample at a room temperature and weigh it again. This

mass will be the mass of oven dry aggregate and is recorded as C;

viii. The bulk specific gravity of coarse aggregate can be calculated by

using the following equation:

Bulk specific gravity = Weight of oven dry aggregates C

Weight of SSD in air B – Weight in water A

3.4.2 Determination of fine aggregate specific gravity

A) Apparatuses:

i. Balance, which should have a capacity of 1 kg and accuracy of

0.1g ;

ii. Pycnometer;

iii. Mould in the form of a frustum of a cone with the following

dimension: 40 ± 3mm inside diameter at the top, 90 ± 3mm inside

diameter at the bottom and 75 ± 3mm in height;

iv. Tamper weighing 340 ± 15kg and have a flat circular face 25 ±

3mm in diameter.

28

C) Procedure:

i. Fine aggregate sample is prepared and 6% water is added to the

total weight of the sample. Sample is permitted to stand for about

24 hours before conducting the test;

ii. Then, a pycnometer is cleaned and weighed empty;

iii. The ¾ filled pycnometer is weighed and its mass is recorded as B;

iv. Afterwards, aggregates are mixed with water until aggregates are

stuck together. Then cone test is carried out. If about 1/3 of

aggregate slumps after 25 light drops of tamper about 10mm

above the top surface of fine aggregate in the cone, then the

aggregates are saturated dry surface;

v. Pour the water away until the pycnometer is left to about ¼ filled;

vi. About 500 g fine aggregate is added to the ¼ filled pycnometer

This weight is recorded as the weight of saturated surface dry

aggregate and it is designated as S;

vii. The pycnometer is filled with water until the original level of ¾ of

its volume (to the calibration mark) and its weight filled with

sample and water is recorded as C;

viii. Shake the pycnometer well for nearly 20 minutes to get rid of air

in the sample;

ix. Dry the sample in an oven until the aggregate achieve a constant

weight. Weigh the oven dry aggregate and record it as A;

29

Figure 3.6: Determination of fine aggregate specific gravity.

x. The specific gravity of fine aggregate can be determined from the

following formula:

Bulk specific gravity = A B + S - C

where:

A: weight of oven dry aggregate in air, gm;

B: weight of pycnometer filled with water, gm;

C: weight of pycnometer with water and aggregate, gm;

S: weight of saturated surface dry aggregate, gm.

3.5 Marshall Mix Design ( ASTM D1559)

The main purpose of the design process is to determine the optimum bitumen

content (OBC) of each asphaltic mixture. For the laboratory tests, all the mixes will

be compacted using two different levels of compaction, which are 75 blows/face for

Asphaltic Concrete mixtures and 50 blows/face for Stone Mastic Asphalt mixtures.

After obtaining the OBC, two samples from each mixture will be prepared using the

obtained OBC and tested for verification to get the realistic volume properties.

The aggregates blend that will be used for mixtures preparation must fall

within the specification requirements. Properties such as density and bulk specific

30

gravity of aggregate and bitumen used for each mixture must be determined earlier

before carrying out Marshall Test.

3.5.1 Mix design preparation

A) The apparatuses that will be used for mix design preparation are:

i. Specimen Mold Assembly;

ii. Compaction Hammer;

iii. Compaction Pedestal;

iv. Specimen Mold Holder;

v. Breaking Head

vi. Oven;

vii. Mixing Apparatus;

viii. Thermometer;

ix. Mixing Tools.

B) Test specimens are:

i. Aggregates mix designation that have been dried at a temperature

of 1050C to 1100C;

ii. Heated asphalt cement.

C) Mixtures Preparation:

i. Aggregates are weighed according to the amount of each size

fraction that required for each mix design;

ii. The pan is heated on a hot plate to a temperature of 280C;

31

iii. Charge the pan with the heated aggregates and dry mix

thoroughly;

iv. Preheated bituminous materials that required to the mixture are

weighted;

v. Prevention of losing the mix during the mixing process must be

taken with subsequent handling. The temperature shall not to be

more than the limits;

vi. Afterwards, aggregates and bitumen are rapidly mixed until

thoroughly until all aggregate are well-coated;

vii. Finally, mixture is removed from the pan and is left a side to be

ready for the compaction process.

D) Compaction of specimens:

The procedure begins with recording the mixture temperature and observing

it until it reaches the desirable compaction temperature. The process will follow the

procedure listed below:

i. The mold assembly and the face of compaction hammer are clean

and heated in a boiling water ,a hot plat or an oven at a

temperature of 930C to 1500C;

ii. Filter paper that is cut into pieces fit the mould’s diameter and

placed at the bottom of the mold before placing the mixtures;

iii. The mixture that has been prepared is then placed in the mold, and

stirred by the spatula or trowel for 15 times around the perimeter

and 10 times over the interior;

32

iv. The collar is removed and the surface will be smoothed with the

trowel to slightly rounded shape;

v. Next, the compaction temperature is recorded once again,

vi. The collar then will be assembled to the compaction pedestal in

the mold holder;

vii. The 75 blows of compaction hammer is applied with a free fall

distance of 500mm from the mold base, and the compaction

hammer is assured to be perpendicular to the base of the mold

assembly;

viii. After compaction, the base plate is removed and the same blows

are compacted to the bottom of the sample that has been turned

around;

ix. After that, the collar is lifted from the specimen carefully,

x. Next, transfer the specimen to smooth surface at a room

temperature for an over-night;

xi. Lastly, record the weight and examine the sample.

Figure 3.7: The specimens that have been prepared by Marshall Mix Design

33

3.5.2 Theoretical Maximum Specific Gravity and Density of Bituminous

Paving Mixtures (ASTM D 2041-91)

A) Scope:

The method covers the determination of the density and theoretical

maximum specific gravity of loose (uncompacted) HMA specimens at 25°C. Test

results are used to compute air voids and density in the compacted mix.

B) Apparatuses:

i. Vacuum container (bowl);

ii. Balance;

iii. Vacuum pump, capable of evacuating air from the vacuum

container to a residual pressure of 30 mm of HG;

iv. Manometer or vacuum gauge;

v. Thermometer; and

vi. Water path.

Figure 3.8: The ASTM D 2041 test apparatus

34

C) Procedure:

i. Size of the sample shall conform to the requirements shown in

table 3.8. Samples larger than the capacity of the container may be

tested a portion at a time.

Table 3.8: Minimum sample size requirement for Theoretical Maximum Density

(ASTM D2041)

Nominal Maximum Aggregate Size Minimum Mass of sample

37.50 mm 4000 gm

25.00 mm 2500 gm

19.0 mm 2000 gm

12.50 mm 1500 gm

9.50 mm 1000 gm

4.75 mm 500 gm

i. Samples are prepared using the same procedure of preparing

Marshall samples but without using any compactive effort;

ii. Particles of the paving mixture sample are separated by hand, so

fine aggregate particles are not larger than 6.3mm (¼in);

iii. Weight of the vacuum container in air is determined before

placing sample and recorded as A;

iv. Also, vacuum container is weighed in water and recorded as B;

v. The sample is cooled to the room temperature, placed into vacuum

container, weighed and recorded as C;

vi. The net mass of sample is recorded as D;

35

vii. Sufficient water is then added to the sample in the vacuum

container and should cover at least 1 inch (2.54 cm) over the

sample;

viii. Air trapped in the sample is removed by increasing the vacuum

gradually until the pressure manometer reads 25mm of HG. This

pressure is maintained for 10 minutes;

ix. During the vacuum period, the container and sample are agitated

continuously by mechanical device;

x. After about 10 minutes, the vacuum is gently released. The

container and sample are then placed in water and weighed. Their

weight is recorded as E;

xi. T.M.D values for different samples must be within ± 0.018 of one

another;

xii. T.M.D value is used to calculate Effective Specific Gravity

(S.Geff) of the aggregate. The calculated (S.Geff) value is used to

determine T.M.D values at binder contents other than the binder

content chosen for mixing T.M.D samples.

1. Calculation:

The theoretical maximum specific gravity (Gmm) can be calculated from the

flowing equation:

Gmm = D / (D+B-E)

where:

D: Weight of sample in air (gm) and can be calculated as

following:

D = C-A (Weight of container & sample in air – weight of

container in air).

36

B: Weight of the bowl in water, gm and

E: Weight of the bowl and sample in water, gm.

The effective specific gravity of aggregate blend used can be determined

using the following formula:

T.M.D = 100 / [(% aggregate / S.G eff) + (% bitumen / S.G bitumen)

3.5.3 Bulk Specific Gravity of Compacted Bituminous Mixtures Using

Saturated Surface-Dry Specimens (ASTM D 2726)

This test covers the determination of bulk specific gravity of the samples.

This method can be only used for a specimen that does not absorb more than 2% of

water by volume. Result from the test is used to calculate the density (unit weight)

and percentage of air voids of compacted mixes. Water displacement method is used

to determine the bulk specific gravity where specimen will be weighed in three

conditions (in air, when submerged in water and saturated dry surface condition).

A) Apparatus that used in this test are listed below:

ii. Balance; and

iii. Water bath.

B) Procedure:

i. First, the specimen is dried to constant mass;

ii. Specimen is cooled to a room temperature at 25±50C and the dry

mass is recorded as A;

iii. Each specimen is immersed in a water path at 250C for 3 to 5

minutes and the immersed mass is then recorded as C;

37

iv. Remove specimen from the water by blotting the surface with a

damp towel and determine the surface-dry mass which designated

as B;

v. The bulk specific gravity can be calculated by using the following

equation;

Bulk specific gravity = AB - C

Viii Bluk specific gravity of Samples at the same binder content must

be within an average of ± 0.020 of one another.

a) The specimen is weight to get the dry air mass.

b) The specimen is immersed to get the mass in water.

38

c) The specimen is wiped with a towel &Weighed to get the surface-dry mass.

Figure 3.9: Steps of Bulk Specific Gravity Test

39

3.5.4 Resistance to Plastic Flow of Bituminous Mixtures Using Marshall

Apparatus (ASTM D1559)

The test covers the measurement of resistance to plastic flow of cylindrical

specimens [101.6mm (4 in) in diameter and 63.5mm (2.5in) high] of asphalt mixture

loaded on the lateral surface by means of Marshall Apparatus. The method is used

for mixtures containing asphalt cement, asphalt cutback and aggregate up to 25.4 mm

maximum size. The purpose of this test is measuring the strength of a compacted

asphaltic mixture to a standard laboratory compactive effort. In addition, the test is

used as apart of Marshall Mix design procedure for selecting design bitumen content.

Figure 3.10: Compression Testing Machine

Marshall testing machine is a compression-testing device, designed to apply

loads to test specimens through semi-circular testing heads at a constant strain rate of

58.5mm/min. (2in/min.). The water path in which the sample is immersed for at least

45minutes, should be at least 150 mm (6in) deep and thermostatically controlled at

60°C±1°C (140°F±1.8°F). The temperature was selected since it is approximately the

maximum pavement temperature in the summer. Thereby, it provides the weakest

condition of HMA mixture.

Flow test is carried out simultaneously with stability test. It is executed by

holding the flow meter over the testing head and reading the meter at the instance the

specimen fails under pressure.

40

The test procedure is listed as below:

i. Specimens that have been prepared are immersed in the water bath

for 30 to 45 minutes at a maintained temperature of 60 ±10C ;

Figure 3.11: Specimens are being immersing in water bath

ii. The guide rods and the tests heads are cleaned prior to carrying

out the test. Also, the guide rods shall be lubricated so that the

upper test slides freely over them;

Figure 3.12: Lubricating of the guide and its rods prior to testing

iii. The testing-head temperature is recommended to be between 210C

to 380C;

41

iv. Specimen then is removed from the water bath and be placed in

the lower segment of the breaking head;

v. After that, the upper segment of the breaking head is placed on the

specimen. The complete assembly is then located in its position on

the testing machine;

Figure 3.13: Breaking head is placed on a sample

vi. The flow meter is placed in position over one of the guide rods;

vii. Then, adjust the flow meter to zero while holding the sleeve

firmly;

Figure 3.14: Sample is placed in Marshall Stability Machine

42

viii. The load is applied to the specimen by means of a constant

movement rate of 50.8mm until the maximum load is reached .

Notice that reading must be taken before loading the specimen;

ix. As the applied load is started to decrease, the dial reading is taken

and recorded as the maximum applied load the sample can sustain

(the stability force);

x. Record the last reading of the flow meter. This value will be taken

as the flow value in mm unit;

xi. Testing must be completed within 30 seconds of removing sample

from the hot water bath;

xii. The applied load must be corrected when thickness of specimen is

other than (2½ in.) or 63.5mm by using the proper multiplying

factor from Table 3.9 below;

Table 3.9: Stability Correlation Ratios

Volume of specimen

(cm³)

Approximate thickness

of Specimen.(mm) Correlation Ratio

444 to 456 55.6 1.25

457 to 470 57.2 1.19

471 to 482 58.7 1.14

483 to 495 60.3 1.09

496 to 508 61.9 1.04

509 to 522 63.5 1.00

523 to 535 65.1 0.96

536 to 546 66.7 0.93

547 to 559 68.3 0.89

560 to 573 69.9 0.86

574 to 585 71.4 0.83

586 to 598 73.0 0.81

43

3.5.5 Volumetric properties of compacted mixtures

The total volume of small pockets of air between the coated aggregate

particles in a compacted paving mixture, expressed as a percentage of the bulk

volume of the compacted paving mixture is defined as the total volume of voids in

mixture (VTM).Voids in total mix can be calculated using this formula :

VTM = [1 - (Gmb / Gmm)] x 100

Or

VTM = (VA / VT) x 100

where:

VTM : Air voids in a compacted mixture.

Gmb : Bulk specific gravity of a compacted mixture.

Gmm : Maximum specific gravity (T.M.D).

VA : Volume of air voids.

VT : Total volume of compacted specimen.

The voids in the mineral aggregate VMA are defined as the intergranular void

spaces between aggregate particles in a compacted paving mixture that include the

air voids and the effective asphalt content (volume of asphalt not absorbed into the

aggregates), expressed as a percentage of the total volume of the compacted paving

mixture. In other words, VMA is the total volume of voids within the mass of the

compacted aggregate. The VMA can be determined by using the following equation:

VMA = (100 - Pb) Gmb / S.Geff

where:

VMA : Voids in mineral aggregate.

Pb : Percentage of asphalt content by total weight of mixture.

S.Geff : Effective specific gravity of aggregates.

Voids filled with asphalt VFA, is defined as the percent of the volume of

VMA that is filled with asphalt cement.VFA can be calculated using the following

formula:

44

VFA = [(VMA – VTM) / VMA] x 100

where:

VFA : Voids filled with asphalt.

VMA : Voids in mineral aggregate.

VTM : Air voids in a compacted mixture.

From density and voids analysis, and results from stability and flow test,

results will be plotted as following:

i. Bulk density versus asphalt content.

ii. Stability versus asphalt content.

iii. Flow versus asphalt content.

iv. % voids in the total mix VTM versus asphalt content.

v. % voids in the aggregate filled with asphalt VFA versus asphalt

content.

For asphaltic concrete mixtures (ACW10, ACW14, and ACB28), the

optimum asphalt content will be determined as described by the National Asphalt

Paving Association (NAPA), which is the percentage of asphalt corresponds to 4%

air voids from VTM curve.

For Stone Mastic Asphalt mixtures (SMA14 and SMA20), the optimum

asphalt content shall be determined by averaging four values of the asphalt content

determined as follows:

i. Peak of curve taken from the stability graph.

ii. Flow equals to 3 mm from the flow graph.

45

iii. Peak of curve taken from the bulk specific gravity graph.

iv. VTM equals to 3.5% from the VTM graph.

The individual tests values (Stability, Flow, VMA and VTM) for stone mastic

asphalt mixtures at the mean optimum bitumen content shall be read from the plotted

smooth curves and comply with the design parameters given in table 3.10 below.

Table 3.10: SMA Mix requirements (JKR/SPJ/rev2005)

Parameter Wearing Course

Stability S

Flow F

Air voids in mix VTM

Voids in mineral aggregate VMA

min. 6200N

2.0-4.0mm

3.0-4.0%

Min. 17%

3.6 Evaluation of Rutting Potential using the Three-Wheel immersion

Tracking Machine

After obtaining the optimum bitumen content, two beams from each mixture

type will be prepared and tested to evaluate rutting potential of each specific mixture.

Beams are of dimension (407mm × 90 mm × 443 mm) and will be tested using the

Three-Wheel immersion Tracking Machine shown in figure 3.17.

The main function of this machine is to evaluate the rutting resistance of

pavement samples loaded by means of moving wheels that simulate the actual

moving loads on the field.

46

3.6.1 Determination of number of roller Passes

A simple trial and error method is usually carried out to determine the

appropriate number of roller passes for a compaction purpose. The numbers of roller

passes have been initially suggested are 20, 30, 40, 80, 100, 150 and 200 passes. The

test procedure is listed as below:

i. First, aggregates are mixed together according to the gradation for

each asphaltic mixture design;

ii. The obtained optimum bitumen content from Marshall test is

added to each mixture accordingly;

iii. After mixing aggregate thoroughly with the optimum bitumen

content, it is decanted into the mould and compacted using

different numbers of roller passes;

Figure 3.15: Decanting of the sample into the mould

iv. The initial number of roller passes are suggested to be 20, 30, 40,

80, 100, 150 and 200 respectively;

v. After compacting, beams are left to cool at a room temperature;

47

Figure 3.16: Sample after compacting ready to be tested

vi. Once beams have been cooled, they are extruded from the mould

and Bulk Specific Gravity test of Compacted Bituminous

Mixtures Using Saturated Surface-Dry Specimens (ASTM D

2726) is conducted;

vii. Voids in total mix is then calculated for all mixtures and plotted

against the number of passes;

viii. Rolling shall be continued as long as it is necessary to achieve the

appropriate requirement stated in JKR aspect;

ix. Compaction is carried out in order to achieve particular densities

of different mixtures. In this research, for all mixtures, the number

of roller passes is selected to be of which produces a percentage of

air voids of about 7%. The 7% air voids is considered as the

typical in-situ percent of air voids after construction a pavement;

x. Voids in total mix is calculated using the following formulas :

T.M.D = 100 / [(% aggregate / S.G eff) + (% bitumen / S.G bitumen)]

Mass of sample in Air

Bulk specific gravity = Mass of SSD sample – Mass in water

VTM = [1 - (Gmb / Gmm)] x 100

48

3.6.2 Procedure of the Three-Wheel Immersion Tracking Machine Test

Three specimens can be tested simultaneously using three moulds. The

moulds are of dimension 407mm × 90 mm × 443 mm. Once samples have been

compacted, the Three-wheel immersion-tracking test is carried out. The procedure of

conduction the test is as listed below:

i. First, the well-compacted samples are placed into the oven for

approximately 3-5 hrs at a temperature of 60°C;

ii. Temperature of the water path in the wheel-tracking machine is

maintained at 60°C;

iii. Before conducting the test, samples are placed in the tracking

machine and immersed in water path for 30 minutes;

iv. The wheel is tracked back and forth with a travel speed about 40

passes/min;

v. One cycle is defined as the backward and forward movement of

the wheel over samples;

vi. Rutting depth is recorded after 500, 1000, 2000 and 5000 passes

respectively;

vii. The reading will be taken at three different placed of each beam to

obtain the average rut depth value;

49

Figure 3.17: The Wheels Immersion Tracking Machine

3.7 Specification

All samples will be prepared according to the JKR/SPJ/rev2005 as a

guideline. The above-mentioned Tables (3.1, 3.2, 3.3, 3.4 and 3.5) show the

appropriate envelopes of combined aggregates gradation and the range of the design

bitumen content that will be used in this study. The optimum bitumen content will be

determined based on NAPA method. The obtained results from the analysis process

will be compared to the JKR/SPJ/rev2005 requirements specifications of all types of

mixtures as given in Tables 3.5 and 3.7.

3.8 Data analysis

The outcome results from the laboratory work will be analyzed and presented

in such a way that reflects the objective of the research. Results will be recorded and

presented as shown in Table 3.11 below.

50

Table 3.11: The suggested form of the obtained results

Parameter

Mixture Stability (N) Flow (mm)

Stiffness

(N/mm)

Rut depth

(mm)

ACW10

ACW14

ACB28

SMA14

SMA20

Lastly, results will be presented and plotted on four different graphs, which

are flow versus rut depth, stability versus rut depth, flow versus stability and stiffness

versus rut depth. This aims to evaluate the relationships between the four main

parameters that are related to pavement performance.

CHAPTER IV

RESEARCH RESULTS AND ANALYSIS

4.1 Introduction

The analysis process of all data obtained by the laboratory work will be

discussed in depth in this chapter. Several tests have been conducted to determine

stability, flow and rut depth values of five different HMA mixtures, which are

(ACW10, ACW14, ACB28, SMA14 and SMA20). These results were obtained

based on the optimum bitumen content that had been determined from Marshall Mix

design method. Tests that were carried out include: dry and washed sieve analysis,

specific gravity for coarse and fine Aggregate test, Marshall Mix design to obtain the

optimum bitumen content, stability and flow test and evaluation of rut depth using

the Three-Wheel immersion tracking machine.

4.2 Aggregate gradation

Aggregate gradation is considered as the centerpiece component of HMA

mixture design. A proper selection of aggregate gradation plays a very significant

role in providing a dense, durable and stable mixture and it is affected almost all

HMA mixture properties.

52

Aggregate gradation was selected according to JKR/SPJ/2005 by choosing

the best curve for each HMA mixture. The best design curves chosen and then

plotted on the power of 0.45 graphs. Based on the design curve, the weight of

retained aggregate on each sieve was determined. Gradation limits and mix design

curve for all five mixtures are shown in figures 4.1(a) to (e).

ACW10 Aggregate Gradation

05

101520253035404550556065707580859095

100105

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5

Sieve Size ^0.45

% P

assi

ng

Lower Limit

Upper Limit

Mix Design Curve

MDL

Figure 4.1 (a) Gradation limits and mix design curve for ACW10

Table 4.1.1: Aggregate gradation for ACW10

Specification Limits (%)

Sieve Size mm

Size^0.45 Lower Upper

Percent Passing

Cumulative retained

Percent retained

14 3.279 100 100 100 0 0 10 2.818 90 100 95 5 5 5.0 2.063 58 72 65 35 30 3.35 1.723 48 64 56 44 9 1.18 1.077 22 40 27 73 29 0.425 0.680 12 26 15 85 12 0.150 0.426 6 14 10 90 5 0.075 0.312 4 8 6 94 4 Filler - - - - 100 6

∑=100 %

53

ACW14 Aggregate Gradation

05

101520253035404550556065707580859095

100105

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25

Sieve Sixe ^0.45

% P

assi

ng

Lower LimitUpper LimitMix Design CurveMDL

Figure 4.1(b): Gradation limits and mix design curve for ACW14

Table 4.1.2: Aggregate gradation for ACW14


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

20 3.850 100 100 100 0 0 14 3.279 90 100 93 7 7 10 2.818 76 86 79 21 14 5.0 2.063 56 62 56 44 23 3.35 1.723 40 54 47 53 9 1.18 1.077 18 34 23 77 24 0.425 0.680 12 24 14 86 9 0.150 0.426 6 14 10 90 4 0.075 0.312 4 8 6 94 4 Filler - - - - 100 6

∑=100 %

54

ACB28 Aggregate Gradation

05

101520253035404550556065707580859095

100105

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50

Sieve Size ^0.45

%P

assi

ng

Lower LimitUpper LimitMix DesignMDL

Figure 4.1(c): Gradation limits and mix design curve for ACB28

Table 4.1.3: Aggregate gradation for ACB28


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

37.5 5.109 100 100 100 - 0 28 4.479 90 100 95 - 5 20 3.850 72 90 85 15 10 14 3.279 58 76 70 30 15 10 2.818 48 64 56 44 14 5.0 2.063 30 46 36 64 20 3.35 1.723 24 40 28 72 8 1.18 1.077 14 28 17 83 11 0.425 0.680 8 20 10 90 7 0.150 0.426 4 10 5 95 5 0.075 0.312 3 7 4 96 1 Filler - - - - 100 4

∑=100%

55

SMA14 Aggregate Gradation

05

101520253035404550556065707580859095

100105110

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50

Sieve Size ^0.45

% P

assi

ng

Lower Limit

Upper Limit

Mix Design

MDL

Figure 4.1(d): Gradation limits and mix design curve for SMA14

Table 4.1.4: Aggregate gradation for SMA14


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

25 4.256 100 100 100 0 0 19 4.479 100 100 100 0 0

12.5 3.850 100 100 100 0 0 9.5 3.279 72 83 77.5 22.5 22.5 4.75 2.818 25 38 31.5 68.5 46 2.36 2.063 16 24 20 80 11.5 0.600 1.723 12 16 14 86 6 0.300 1.077 12 15 13.5 86.5 0.5 0.075 0.680 8 10 9 91 4.5 filler - - - - 100 9

∑=100%

56

SMA20 Aggregate Gradation

05

101520253035404550556065707580859095

100105

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50

Sieve Size ^0.45

% P

assi

ng

Lower Limit

Upper Limit

Mix Design Curve

MDL

Figure 4.1(e): Gradation limits and mix design curve for SMA20

Table 4.1.5: Aggregate gradation for SMA20


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

25 4.256 100 100 100 0 0 19 4.479 100 100 100 0 0

12.5 3.850 85 95 90 10 10 9.5 3.279 65 75 70 30 20 4.75 2.818 20 28 24 76 46 2.36 2.063 16 24 20 80 4 0.600 1.723 12 16 14 86 6 0.300 1.077 12 15 13.5 86.5 0.5 0.075 0.680 8 10 9 91 4.5 PAN - - - - 100 9

∑=100%

57

4.3 Sieve Analysis

4.3.1 Dry-Sieve Analysis

Sieve analysis was conducted as the first step in Marshall Design process to

divide aggregates into different sizes and obtain the desired aggregate gradation

required for each mixture design. The aggregate gradations for different mixtures

were used in this project are shown in appendix A.

4.3.2 Washed-Sieve Analysis

Washed-sieve analysis was conducted after all the aggregates samples had been

prepared. This test was carried out to get the amount of filler (aggregate with size

smaller than 75µm) coated on the courser aggregates to determine the required

amount of fillers need to be added for each mixture type. Appendix A shows the wet

sieve analysis results of all mixtures.

4.4 Bulk Specific Gravity of Aggregate

Bulk specific gravity of coarse and fine aggregates was determined form the

laboratory tests. Aggregates used in this research were provided from two different

sources (quarries). Aggregates for ACW mixtures were supplied from MRP quarry.

Whereas for SMA mixtures, aggregates were supplied from handsun quarry.

Based on the aggregate gradation for mixes design, tests were conducted to

determine the bulk specific gravity for aggregate from different sources. For ACW

mixtures, test was carried out based on ACW10 aggregate gradation. By identifying

the percentage of coarse, fine aggregate and mineral filler, the bulk specific gravity

of blend aggregate was determined. For SMA mixtures, aggregate gradation for

58

SMA14 was used to determine the specific gravity of coarse and fine aggregates.

Steps of calculating the bulk specific gravity are shown in Appendix B

4.4.1 Bulk Specific Gravity of Coarse Aggregates

Samples were prepared for testing for both sources of aggregate. For

asphaltic concrete for wearing and binder coarse, sample of coarse aggregate used to

determine its specific gravity has been prepared based the aggregate gradation for

ACW10. Aggregate size in the range of 20mm to 5mm was considered as coarse

aggregate when preparing sample for specific gravity determination. The obtained

results of coarse aggregate specific gravity of different mixtures are clarified in table

4.2 below.

Table 4.2: Bulk specific gravity of coarse aggregate for different mixtures

Mixture type ACW10 ACW14 ACB28 SMA14 SMA20

Coarse Aggregate Specific

Gravity (S.Gbulk) 2.586 2.586 2.586 2.611 2.611

4.4.2 Bulk Specific Gravity of Fine Aggregates

Sizes of aggregate that were considered as fines to find its specific gravity

were from 3.35mm and below. This also was based the aggregate gradation for

asphaltic cement for wearing coarse ACW10 and fro Stone Mastic Asphalt SMA 14.

The obtained results of fine aggregate specific gravity of different mixtures are

shown in Table 4.3 below.

59

Table 4.3: Bulk specific gravity of fine aggregate for different mixtures


Fine Aggregate Specific

Gravity(S.Gbulk) 2.522 2.522 2.522 2.707 2.707

4.4.3 Mineral Filler Specific Gravity

Ordinary Portland Cement (OPC) has been largely used as filler material for

Marshall Mix .Therefore; it was used in this research as well. It serves as a pond

agent in asphaltic mixtures between aggregate and bitumen. According to previous

work has been carried out in Highway & Transportation laboratory at UTM, the

specific gravity of the OPC was 2.980.

4.4.4 Bulk Specific Gravity of Total Aggregate ( S.GBlend )

Based on the percentage of Coarse, Fine aggregate and mineral filler of each

mixture, the bulk specific gravity of aggregate blend for each mix design was

determined. Table 4.4 shows the results were obtained for different mixtures. By

identifying the specific gravity of coarse and fine aggregate and the percentage of

coarse, fines and mineral filler for each mixture, the bulk specific gravity of total

mixture could be determined.

Table 4.4: Bulk specific gravity of Blend for different mixtures


Combined aggregate specific

gravity (S.GBlend)bulk 2.551 2.557 2.570 2.641 2.634

The specific gravity of blend has been determined by using the following

equation:

60

S.GBlend ( bulk) =

For example, S.GBlend for ACW 10 has been determined as following:

S.GBlend (ACW10) = = 2.551 (35 / 2.586) + (63 / 2.522) + (2 / 2.98)

100

(% coarse Agg. / SG coarse) + (% fine Agg. / SG fin e) + (% filler / SG filler) 100

4.5 Specific Gravity of Bitumen

Bitumen of 80/100 PEN (penetration) grade was used in this study for

asphaltic concrete for wearing and binder coarse mixtures. Whereas for Stone Mastic

Asphalt mixture, Bitumen of PG76 performance grade was used. Previous studies

that have been conducted in Transportation and Highway laboratory at UTM

concluded that specific gravity of bitumen was (1.03) for both types.

4.6 Maximum Specific Gravity of Paving Mixtures

Two methods can be used to calculate the maximum specific gravity of loose

asphaltic mixture. The laboratory test (Rice Method) was used in this research. By

doing so, the theoretical maximum density of loose mixture can be calculated

directly. Table 4.5 shows the obtained results from the laboratory test for all mixtures

used in this research.

Table 4.5: Theoretical Maximum density of all used mixtures


Maximum specific gravity

(Gmm) or T.M.D 2.401 2.411 2.457 2.414 2.416

61

Theoretical maximum densities were used to calculate the effective specific

gravity of aggregate. Then, the maximum specific gravity at any asphalt content was

determined using this formula:

TMD = 100 (% coarse agg. / SGeff. blended) + (% bitumen / SGbitumen)

Table 4 .6 shows the maximum specific gravity at each asphalt content for each

mixtures used in this research.

Table 4.6: Theoretical Maximum density at each asphalt Content for each asphaltic

mixture

Maximum Specific Gravity (Gmm) T.M.D Asphalt

Content % ACW10 ACW14 ACB28 SMA14 SMA20

3.50 - - 2.481 - -

4.00 - - 2.463 - -

4.50 - 2.445 2.446 - -

5.00 2.435 2.427 2.428 2.449 2.452

5.50 2.418 2.410 2.411 2.432 2.434

6.00 2.401 2.393 - 2.414 2.416

6.50 2.384 2.376 - 2.397 2.400

7.00 2.367 - - 2.380 2.383

OBC 2.387 2.435

4.7 Effective Specific Gravity of Aggregate

The effective specific gravity of aggregate was calculated based on the

obtained values of the maximum specific gravity of loose mixture. The effective

specific gravity of aggregate is used in analyzing of volumetric properties of paving

mixtures. The effective densities used for analysis process of each mixture are shown

in table 4.7.

62

Table 4.7: Effective Specific Gravity of each mixture used in this research


Combined aggregate

specific gravity

(S.G effective blend)

2.624 2.614 2.615 2.641 2.644

4.8 Volumetric Properties Analysis

The volumetric properties which includes voids in total mix (VTM), voids

filled with bitumen (VFB) and voids in mineral aggregate (VMA) for all types of

mixtures (ACW10, ACW14, ACB28, SMA14 and SMA 20) were calculated based

on the effective specific gravity of aggregate.

4.8.1 Voids in total mix (VTM)

The voids in total mix were calculated based on the maximum specific

gravity of loose mixes (Gmm) and the bulk specific gravity of compacted mixes

(Gmb). Results were obtained are shown in Table 4.8.

Table 4.8: Percentage of VTM for different mixtures

VTM (%) Asphalt


3.50 - - 6.9 - -

4.00 - - 5.3 - -

4.50 - 8.1 5.0 - -

5.00 7.7 5.7 3.5 9.2 7.2

5.50 6.3 5 3.2 8.4 6.1

6.00 5.6 3.9 - 7.0 5.4

6.50 3.3 2.4 - 7.1 4.4

63

7.00 2.8 - - 5.8 4.2

7.10 - - - - 5.7

7.70 - - - 7.1 -

8.20 - - - 6.3 -

9.60 - - - 2.1 -

4.8.2 Voids in mineral aggregate (VMA)

Table 4.9: Percentage of VMA for different mixtures

VMA (%) Asphalt


3.50 - - 14.8 - -

4.00 - - 14.4 - -

4.50 - 17.9 15.1 - -

5.00 18.6 16.8 14.9 20.0 18.0

5.50 18.4 17.2 15.7 20.3 18.0

6.00 18.8 17.3 - 20.1 18.4

6.50 17.9 17.0 - 21.1 18.6

7.00 18.5 - - 21.0 19.4

7.10 - - - - 20.9

7.70 - - - 23.5 -

8.20 - - - 23.7 -

9.60 - - - 23.0 -

64

4.8.3 Voids Filled with Bitumen (VFB)

Table 4.10: Percentage of VFB for different mixtures

VFB (%) Asphalt


3.50 - - 53.2 - -

4.00 - - 62.9 - -

4.50 - 54.9 67.2 - -

5.00 58.5 66.2 76.2 54.0 61.4

5.50 65.9 71.1 79.4 58.6 67.8

6.00 70.2 77.4 - 65.2 72.5

6.50 81.5 86.0 - 66.7 78.0

7.00 84.7 - - 72.4 79.8

7.10 - - - - 74.1

7.70 - - - 69.8 -

8.20 - - - 73.7 -

9.60 - - - 91.0 -

4.9 The Optimum Bitumen Content

There are various methods to obtain the optimum bitumen content of HMA

mixtures. The Asphalt Institute Method and National Asphalt Pavement Association

(NAPA) method are world well-known methods and have been used widely. In this

research, it was proposed to determine the optimum content according to JKR

requirements but due to difficulties in meeting the requirement of JKR specification

(getting the peak of Stability and Density curves), there has become possible to

follow NAPA method as an available proper option. According to this method, the

optimum asphalt content is selected in corresponding to 4% VTM.

Table 4.11: The Optimum Bitumen Content of asphaltic mixes


Optimum Bitumen Content, % 6.30 5.80 4.80 8.70 8.00

65

4.10 Marshall mix design results of different mixtures at the optimum

bitumen content

After carrying out Marshall Mix design for all 5 mixtures and obtaining the

optimum asphalt content for each mixture, verification test was performed by

preparing 2 samples from each mix to evaluate volumetric properties, stability and

flow values using the OBC. Results are shown in Table 4.12.

Table 4.12: Marshall Mix design results for different mixtures

Mixture Property Mixture Type Test Result Requirement

ACW10 4.1 3% - 5%

ACW14 3.9 3% - 5%

ACB28 4.1 3% - 7%

SMA14 4.2 3% - 5%

VTM, %

SMA20 4.1 3% - 5%

ACW10 18.2 -

ACW14 16.9 -

ACB28 15 -

SMA14 23 Min. 17%

VMA, %

SMA20 21.9 Min. 17%

ACW10 77.2 70% - 80%

ACW14 77.1 70% - 80%

ACB28 72.7 65% - 75%

SMA14 81.9 -

VFB, %

SMA20 81.6 -

ACW10 12370 Min. 8000 N

ACW14 11970 Min. 8000 N

ACB28 7982 Min. 8000 N

SMA14 10490 Min. 6200 N

Stability, N

SMA20 9530 Min. 6200 N

66

ACW10 4.03 2 - 4 mm

ACW14 3.65 2 - 4 mm

ACB28 7.3 2 - 4 mm

SMA14 11 2 - 4 mm

Flow, mm

SMA20 14 2 - 4 mm

ACW10 3096.4 Min 2000 N

ACW14 3230.1 Min 2000 N

ACB28 1099 Min 2000 N

SMA14 953.3 -

Stiffness, N/mm

SMA20 680.7 -

Results achieved by Marshall Mix design method were acceptable. All values

of Optimum bitumen content were complied with the JKR requirements. Except for

SMA mixtures, where the obtained OBC values were complied with AASHTO

requirements, which specifies that the minimum OBC should be 6%. Verification has

approved that all volumetric properties, stability and flow values were complied with

the requirements of JKR specification

4.11 Evaluation of Rut Depth using the Three-Wheel immersion

Tracking Machine

4.11.1 Determination of Number of Roller Passes

Once the optimum bitumen content of all mixtures had been obtained, two

beams from each mixture batched, mixed and compacted to be tested in the Three-

Wheel tracking machine for rutting evaluation.

Identifying the required number of roller passes to achieve the appropriate

requirement of the degree of compaction was the most crucial step before carrying

out the Three-Wheel immersion-tracking machine. ACW14 mixture was selected to

be the representative mixture to identify the required number of roller passes that

produces the required percentage of VTM for each mixture after rolling. Based on

67

JKR aspect, the number of roller passes was selected to be which produces VTM of

about 7% (the typical in-place air voids after construction and opening the road to

traffic).

Numbers of Roller passes that were initially used for the trial and error

method are 20, 30, 40, 80, 100, 150 and 200 passes receptively. Specific gravity of

each beam was determined in order to obtain the percentage of air voids after rolling.

By plotting the relationship of number of roller passes versus percentage of air voids,

the required number of passes was determined. It was concluded that the number of

roller passes required to produce 7% VTM was about 200 roller passes which was

selected to be the same number of roller passes for all mixtures. The process of

carrying out the trial and error method is shown in Appendix C.

Table 4.13: Results of determining required number of roller passes

Number of roller passes Bulk Specific Gravity % VTM

20 2.179 9.40

30 2.179 9.38

40 2.183 9.22

80 2.196 8.69

100 2.200 8.51

150 2.218 7.76

200 2.221 7.12

Results from the trial and error method to determine the number of roller

passes required to produce the appropriate requirement of compaction density have

proven that as number of roller passes is increased, density is increased. On the other

hand, as number of roller passes is increased, the percentage of VTM showed the

opposite trend and decreased.

68

Number of Roller Passes vs %VTM

R2 = 0.88

7.507.607.707.807.908.008.108.208.308.408.508.608.708.808.909.009.109.209.309.409.509.609.70

15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155

Number of Roller Passes

VTM

%

Figure 4.2: Number of roller passes versus %VTM

4.11.2 Conducting the Three-Wheel Immersion Tracking Test

Once the required number of roller passes had been identified, two beams of

each mixture were prepared to carry out the rutting evaluation test. The machine is

applicable to test three beams simultaneously. A total number of ten beams were

tested. Results were collected up to the maximum allowable number of rolling which

is 5000 roller passes. Results were obtained from this test are shown in Table 4.14.

Table 4.14: Results of the Three-Wheel immersion-tracking machine

Average Rut Depth (mm) Number of Roller Passes

ACW10 ACW14 ACB28 SMA14 SMA20

0 0 0 0 0 0

500 7.31 8.89 2.93 6.52 1.99

1000 9.88 10.98 3.59 8.34 2.12

2000 10.59 11.90 4.47 9.23 2.28

5000 15.69 14.81 8.2 14.01 4.06

69

Number of Roller Passes versus Rutting Depth

R2 = 0.995

R2 = 0.999

R2 = 0.995

R2 = 0.988

R2 = 0.990

0

2.5

5

7.5

10

12.5

15

17.5

20

22.5

25

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500

Number of Roller Passes

Rut

ting

Dep

th (m

m)

ACW10

ACB28

SMA14

SMA20

ACW14

Power (SMA20)

Power (ACB28)

Power (SMA14)

Power (ACW10)

Power (ACW14)

Figure 4.3: Roller Passes versus Rut Depth results

Finally, stability, flow, stiffness and rut depth values of each mix at the

optimum bitumen content were collected and presented as shown in table 4.15.

Table 4.15: Stability, Flow, Stiffness and Rut depth of various asphaltic mixtures

Mixture

Type

Flow

(mm)

Stability

(N)

Stiffness

(N/mm)

Rut Depth

(mm)

ACW10 4.03 12370 3096.4 15.69

ACW14 3.65 11790 3230.1 14.81

ACB28 7.30 7982 1093.4 8.20

SMA14 11.00 10490 953.6 14.01

SMA20 14.00 9530 680.7 4.06

The obtained relationships between the four parameters that are related to

pavement performance (Stability, Flow, Stiffness and Rut depth) are drawn on

graphs 4.4(a) to (d) as shown below.

70

Stability versus Rutting

R2 = 0.656

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

16.00

17.00

18.00

7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500

Stability (N)

Rut

Dep

th (m

m)

Series1Poly. (Series1)

Figure 4.4(a): Stability versus Rut Depth

Flow versus Rutting

R2 = 0.518

4.004.505.005.506.006.507.007.508.008.509.009.50

10.0010.5011.0011.5012.0012.5013.0013.5014.0014.5015.0015.5016.00

3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 14 14.5

Flow (mm)

Rut

Dep

th (m

m)

Series1Power (Series1)

Figure 4.4(b): Flow versus Rut Depth

71

Flow versus Stability

R2 = 0.345

7500

7750

8000

8250

8500

8750

9000

9250

9500

9750

10000

10250

10500

10750

11000

11250

11500

11750

12000

12250

12500

3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5

Stab

ility

(N)

Flow (mm)

Series1Power (Series1)

Figure 4.4(c): Flow versus Stability

Stiffness versus Rutting

R2 = 0.490

2.5

3.5

4.5

5.5

6.5

7.5

8.5

9.5

10.5

11.5

12.5

13.5

14.5

15.5

16.5

17.5

18.5

500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500

Stiffness (N/mm)

Rut

Dep

th (m

m)

Series1Expon. (Series1)

Figure 4.4(d): Stiffness versus Rut Depth

72

4.12 DISCUSSION

Results of this research will be discussed in this part and conclusion would be

drawn based on it. The conclusion and recommendations will be presented in the

next chapter.

Results achieved by Marshall Mix design method were acceptable. All values

of Optimum bitumen content were complied with the JKR requirements. Except for

SMA mixtures, where the obtained OBC values were complied with AASHTO

requirements, which specifies that the minimum OBC should be 6%. Verification has

approved that all volumetric properties, stability and flow values were complied with

the requirements of JKR specification.

Results from the trial and error method to determine the number of roller

passes required to produce the appropriate requirement of compaction density have

proven that as number of roller passes is increased, density is increased. On the other

hand, as number of roller passes is increased, the percentage of VTM showed the

opposite trend and decreased.

It was observed that from the Three-Wheel immersion tracking machine test,

the relationships between flow and stability is weak which indicated a poor

correlation with R² value of 0.345. Results show that as flow is increased, stability is

increased which is not acceptable.

As presented in stability versus rut depth graph, the obtained relationship

shows a fair correlation with R² of (0.656). The relationship suggests that as stability

is increased, rut depth is also increased which is not expected. Particularly, as a

material becomes more stable, rutting potential should be decreased. Therefore, it

was concluded that stability can not be used to predict rutting potential of the new

Malaysian HMA mixtures.

By plotting the relationships between flow and rut depth, the trend indicated

that while flow value is increased, rut depth shows an opposite intend and decreased

73

which is unexpected. Normally, as flow is increased, rut depth is increased. Although

the correlation is fair with R² of 0.518 but this again shows that, flow can not predict

rutting potential.

An attempt was made to investigate the relationship between stiffness (which

is the ratio of stability divided by flow value) and rut depth. The obtained

relationship shows a weak (poor) correlation with R² of (0.49) and indicates that

stiffness does not have much reliability. Therefore, the trend a show that as stiffness

is increased, the rut depth is also increased which is against the understanding of

asphalt behavior. It is concluded that stiffness cannot be used as an indicator of

rutting potential. Typically, the stiffer the mix, the less the rut depth or in other

words, the higher the stiffness, the lower the rut depth which does not exist from th

obtained relationship.

CHAPTER V

CONCLUSION AND RECOMMONDATIONS

From this study, it can be concluded that there is no correlation between

stability, flow and rutting potential .Therefore, stability flow and stiffness cannot be

used to predict rutting potential of the new Malaysia HMA mixtures.

To improve the findings it might be helpful for future researches to be carried

out using a modern Wheel tracking machine (e.g. Hamburg Wheel-Tracking

Machine) and make a comparison of the results with the achieved results by the

Three-Wheel immersion Tracking Machine used in this research.

It should be noted that the results were obtained based on a level of

compaction of 75 blows/face for AC mixtures and 50 blows/face for SMA mixtures.

Using different levels of compaction could be useful to study the correlation between

stability, flow, stiffness and rut depth of various mixes at different levels of

compaction.

75

REFERENCES

1. Freddy L. Roberts, Prithvi S.Kandhal, E. Ray Brown,Dah-Yinn Lee,Thomas

W. Kennnedy. NAPA research and education foundation. “Hot mix asphalt

materials, mixtures, design and construction”. 2nd edition; 1996.

2 “Asphalt paving technology”. Proceedings association of asphalt paving

technologists. Technical sessions. Volume 58; 1989

3. Harold N. Atkins, PE. “Highway materials, soils and concrete”. 4th edition;

2004.

4. “A guide to the visual assessment of flexible pavement surface conditions”.

Jabatan Kerja Malaysia; 1992.

5. Asphalt Institute, Lexington, Kentucky “Mix Design Methods for Asphalt

Concrete and Other Hot-Mix Types “. Manual Series No.2 (MS-2). 6th

Edition; 1996.

6. Eisenmann, J., and A. Hilmer. “Influence of Wheel Load and Inflation

Pressure on the Rutting Effect at Asphalt-Pavements-Experiments and

Theoretical Investigations.”. Proceedings, Sixth International Conference on

the Structural Design of Asphalt Pavements, Vol. I, Ann Arbor, 392-403,;

1987.

7. Van de Loo, P.J “Creep Testing, a Simple Tool to Judge Asphalt Mix

Stability.” Proceeding of the Association of Asphalt Paving Technologists,

Volume 43; 1974.

76

8. Ray Brown, Prithvi Kandhal and Jingna Zhang “Performance Testing for Hot

Mix Asphalt, Executive Summary”. NCAT Report No. 2001-05A, Nov. 2001.

9. Texas Department of Transportation TDOT “Manual of Testing Procedures”.

10. Buchanan, M. S. An Evaluation of Laboratory Wheel-Tracking Devices.

National Asphalt Pavement Association, National Center for Asphalt

Technology; Aug. 1997.

11. Williams, C. R. and B. D. Prowell. Comparison of Laboratory Wheel-

Tracking Test Results to WesTrack Performance. Presented at the 78th

Annual Meeting of the Transportation Research Board, Washington, D.C; Jan

1999.

12. West, R. C., G. C. Page, K. H. Murphy. Evaluation of the Loaded Wheel

Tester.Research Report FL/DOT/SMO/91-391, Florida Department of

Transportation; Dec.1991.

13. E.RAY BROWN,PRITHVI S. KANDHAL, JINGNA ZHANG. National

Center for Asphalt Technology “performance testing for Hot-Mix Asphalt”.

14. PRITHVI S. KANDHAL, Rajib B. Mallick, “Effect of aggregate gradation

on permanent deformation potential of dense graded Hot-Mix Aspahlt”.

15. Stephen A. Cross, Alex Ad-Osei, and Mohd Rosli Hainin “Effects of

aggregate gradation on performance of asphalt mixtures”; JAN1999.

16. E.R BROWNand STEPHEN A. CROSS. “A study of in-place rutting of

asphalt pavement”.

17. HAPI Asphalt Pavement Guide. Hawai'I asphalt paving industry.

77

18. Ludomir Uzarowski, Michel Paradis, Paul Lum,” accelerated performance

testing of Canadian asphalt mixes using three different wheel rut testers”;

2004.

19. Myron Thiessen, Ahmed Shalaby, Leonnie Kavanagh “Strength testing of in-

service asphalt pavement in Manitoba and correlation to rutting”; 2000.

APPENDIXES

79

APPENDIX A

1) Aggregate gradation

Table A1.1: Aggregate gradation for ACW10


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

14 3.279 100 100 100 0 0 10 2.818 90 100 95 5 5 5.0 2.063 58 72 65 35 30 3.35 1.723 48 64 56 44 9 1.18 1.077 22 40 27 73 29 0.425 0.680 12 26 15 85 12 0.150 0.426 6 14 10 90 5 0.075 0.312 4 8 6 94 4 Filler - - - - 100 6

∑=100 %

Table A1.2: Aggregate gradation for ACW14


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

20 3.850 100 100 100 0 0 14 3.279 90 100 93 7 7 10 2.818 76 86 79 21 14 5.0 2.063 56 62 56 44 23 3.35 1.723 40 54 47 53 9 1.18 1.077 18 34 23 77 24 0.425 0.680 12 24 14 86 9 0.150 0.426 6 14 10 90 4 0.075 0.312 4 8 6 94 4 Filler - - - - 100 6

∑=100 %

80

Table A1.3: Aggregate gradation for ACB28


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

37.5 5.109 100 100 100 - 0 28 4.479 90 100 95 - 5 20 3.850 72 90 85 15 10 14 3.279 58 76 70 30 15 10 2.818 48 64 56 44 14 5.0 2.063 30 46 36 64 20 3.35 1.723 24 40 28 72 8 1.18 1.077 14 28 17 83 11 0.425 0.680 8 20 10 90 7 0.150 0.426 4 10 5 95 5 0.075 0.312 3 7 4 96 1 Filler - - - - 100 4

∑=100%

Table A1.4: Aggregate gradation for SMA14


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

25 4.256 100 100 100 0 0 19 4.479 100 100 100 0 0

12.5 3.850 100 100 100 0 0 9.5 3.279 72 83 77.5 22.5 22.5 4.75 2.818 25 38 31.5 68.5 46 2.36 2.063 16 24 20 80 11.5 0.600 1.723 12 16 14 86 6 0.300 1.077 12 15 13.5 86.5 0.5 0.075 0.680 8 10 9 91 4.5 filler - - - - 100 9

∑=100%

81

Table A1.5: Aggregate gradation for SMA20


Sieve Size mm


Percent Passing

Cumulative retained

Percent retained

25 4.256 100 100 100 0 0 19 4.479 100 100 100 0 0

12.5 3.850 85 95 90 10 10 9.5 3.279 65 75 70 30 20 4.75 2.818 20 28 24 76 46 2.36 2.063 16 24 20 80 4 0.600 1.723 12 16 14 86 6 0.300 1.077 12 15 13.5 86.5 0.5 0.075 0.680 8 10 9 91 4.5 PAN - - - - 100 9

∑=100%

82

2) Dry & Washed-Sieve Analysis Results

A) Dry & Washed-Sieve Analysis Test for ACW10

Dry-Sieve analysis results

Table A2.1: Aggregate gradation & required weight of each aggregate size for

ACW10 mixture

Sieve Size mm Size^0.45 Percent

Passing Percent retained

Weight required (gm)

Cumulative Weight

14 3.279 100 % 0 % 0 0 10 2.818 95 % 5 % 60 60 5.0 2.063 65 % 30 % 360 420 3.35 1.723 56 % 9 % 108 528 1.18 1.077 27 % 29 % 348 876 0.425 0.680 15 % 12 % 144 1020 0.150 0.426 10 % 5 % 60 1080 0.075 0.312 6 % 4 % 48 1128 PAN - - 6 % 72 1200

∑ =100 % ∑ = 1200

Washed-Sieve analysis results

Table A2.2: Washed-sieve analysis result

Sample No. 1 2 Weight of sample before washing, A (g) 1128.0 1128.0 Weight of oven dry sample in air (after washing), B (g) 1079.3 1076.0 Amount of Dust coated on aggregate = A - B 48.70 52.00

Average = 50.35gm

83

Percentage of required filler material for ACW10

Percentage of dust (Filler) = 6% (2% OPC + 4%filler).

2 % OPC (Ordinary Portland Cement) = 0.02×1200 = 24gm.

4 % filler = 0.04×1200 = 48gm.

Amount of dust cotaed on the aggregate ≈ 50gm.

Since the required dust is almost the same amount of dust coated on the aggregate,

only the percentage of OPC (24gm) has been added to total weight of aggregate.

Table A2.3: Final Aggregate gradation used to prepare Marshall samples For

ACW10 after determining amount of dust content coated oaggregates

Sieve Size

mm

% retained

Cumulative Weight of

agg.

@ 5.0 %

@ 5.5 %

@ 6.0 %

@ 6.5 %

@ 7.0 %

14 0 % 0 0 0 0 0 0

10 5 % 60 60 60 60 60 60

5.0 30 % 420 360 360 360 360 360

3.35 9 % 528 108 108 108 108 108

1.18 29 % 876 348 348 348 348 348

0.425 12 % 1020 144 144 144 144 144

0.150 5 % 1080 60 60 60 60 60

0.075 4 % 1128 48 48 48 48 48

OPC 2 % 1152 24 24 24 24 24 Added Dust 0 % 0 0 0 0 0 0

Weight of bitumen - - 60.63 67.04 73.53 80.08 86.70

Total Weight

of sample - - 1212.63 1219.04 1225.53 1232.08 1232.7

84

B) Dry & Washed-Sieve Analysis Test for ACW14



ACW14 mixture




Cumulative Weight

20 3.850 100 % 0 % 0 0 14 3.279 93 % 7 % 84 84 10 2.818 79 % 14 % 168 252 5 2.063 56 % 23 % 276 528

3.35 1.723 47 % 9 % 108 636 1.18 1.077 23 % 24 % 288 924 0.425 0.680 14 % 9 % 108 1032 0.15 0.426 10 % 4 % 48 1080 0.075 0.312 6 % 4 % 48 1128 PAN 0 0 % 6% 72 1200

∑ =100 % ∑ = 1200



Sample No. 1 2 Weight of sample before washing, A (g) 1128.0 1128.0 Weight of oven dry sample in air(after washing), B (g) 1084.3 1086.1 Amount of Dust coated on aggregate = A - B 43.70 41.90

Average =42.80gm

85

Percentage of required filler material for ACW14



4 % filler = 0.04×1200 = 48gm.

Amount of dust coated on the aggregate ≈ 42.80gm.

Then, 48 - 42.80 = 5.2gm. filler that must be added to the total weight of aggregate.

Table A3.3: Final Aggregate gradation used to prepare Marshall samples for

ACW14 after determining amount dust content coated an the aggregate

Sieve Size

mm

% retained


agg.

@ 5 %

@ 5.5 %

@ 6 %

@ 6.5 %

@ 7 %

14 0 % 0 0 0 0 0 0

10 5 % 60 60 60 60 60 60

5.0 30 % 420 360 360 360 360 360

3.35 9 % 528 108 108 108 108 108

1.18 29 % 876 348 348 348 348 348

0.425 12 % 1020 144 144 144 144 144

0.150 5 % 1080 60 60 60 60 60

0.075 4 % 1128 48 48 48 48 48

OPC 2 % 1152 24 24 24 24 24 Added Dust 0.43 % 1157.2 5.2 5.2 5.2 5.2 5.2

Weight of

bitumen - - 60.63 67.04 73.53 80.08 86.70

Total Weight

of sample

- - 1217.83 1224.24 1230.73 1237.28 1243.90

86

C) Dry & Washed-Sieve Analysis Test for ACB28



ACB28 mixture




Cumulative Weight

37.5 5.109 100 % 0 % 0 0 28 4.479 95 % 5 % 60 60 20 3.850 85 % 10 % 120 180 14 3.279 70 % 15 % 180 360 10 2.818 56 % 14 % 168 528 5 2.063 36 % 20 % 240 768

3.35 1.723 28 % 8 % 96 864 1.18 1.077 17 % 11 % 132 996 0.425 0.680 10 % 7 % 84 1080 0.15 0.426 5 % 5 % 60 1140 0.075 0.312 4 % 1 % 12 1152 Pan 0 0 % 4 % 48 1200

∑ =100 % ∑ = 1200



Sample No. 1 2 Weight of sample before washing, A (g) 1152.0 1152.0 Weight of oven dry sample in air(after washing), B (g) 1128.0 1131.1 Amount of Dust coated on aggregate = A - B 24.00 20.90

Average =22.45gm

87

Percentage of required filler material for ACB28



2 % filler = 0.02×1200 = 24gm.


Then, 24 - 22.45 = 1.55gm. filler that must be added to the total weight of aggregate.

Table A4.3: Final Aggregate gradation used to prepare Marshall samples for ACB28

after determining amount dust content coated an the aggregate

Sieve Size

mm

% retained


agg.

@ 3.5 %

@ 4.0 %

@ 4.5 %

@ 5.0 %

@ 5.5 %

37.5 0 % 0 0 0 0 0 0

28 5 % 60 60 60 60 60 60

20 10 % 180 120 120 120 120 120

14 15 % 360 180 180 180 180 180

10 14 % 528 168 168 168 168 168

5.0 20 % 768 240 240 240 240 240

3.35 8 % 864 96 96 96 96 96

1.18 11 % 996 132 132 132 132 132

0.425 7 % 1080 84 84 84 84 84

0.150 5 % 1140 60 60 60 60 60

0.075 1 % 1152 12 12 12 12 12

OPC 2 % 1176 24 24 24 24 24 Added Dust 0.1291% 1177.55 1.55 1.55 1.55 1.55 1.55

Weight of

bitumen - - 42.70 49.10 55.50 62.00 68.60

Total Weight

of sample

- - 1220.25 1226.65 1233.1 1239.55 1246.15

88

D) Dry & Washed-Sieve Analysis Test for SMA14



SMA14 mixture




Cumulative Weight

25 4.256 100 100 100 0 19 3.762 100 % 0 % 0 0

12.5 3.116 100 % 0 % 0 0 9.5 2.754 77.5 % 22.5 % 270 270 4.75 2.016 31.5 % 46 % 552 822 2.36 1.472 20 % 11.5 % 138 960 0.6 0.795 14 % 6 % 72 1032 0.3 0.582 13.5 % 0.5 % 6 1038

0.075 0.312 9 % 4.5 % 54 1092 Pan 0 0 % 9 % 108 1200

∑ =100 % ∑ = 1200



Sample No. 1 2 Weight of sample before washing, A (g) 1092 1092 Weight of oven dry sample in air(after washing), B (g) 1069.1 1071.5 Amount of Dust coated on aggregate = A - B 22.9 20.5

Average = 21.7gm

89

Percentage of required filler material for SMA14

Percentage of dust (Filler) = 9% (Ortdinary Portland Cement).

9 % OPC (Ordinary Portland Cement) = 0.09*1200 = 108gm.


Then, 108 - 21.7 = 86.3gm OPC that must be added to the total weight of aggregate.

Table A5.3: Final Aggregate gradation used to prepare Marshall samples for SMA14


Sieve Size

mm

% retained


agg.

@ 5.0 %

@ 5.5 %

@ 6.0 %

@ 6.5 %

@ 7.0 %

25 4.256 0 0 0 0 0 0

19 0 % 0 0 0 0 0 0

12.5 0 % 0 0 0 0 0 0

9.5 22.5 % 270 270 270 270 270 270

4.75 46 % 822 552 552 552 552 552

2.36 11.5 % 960 138 138 138 138 138

0.6 6 % 1032 72 72 72 72 72

0.3 0.5 % 1038 6 6 6 6 6

0.075 4.5 % 1092 54 54 54 54 54

OPC 7.19 % 1178.3 86.3 86.3 86.3 86.3 86.3 Added Dust 0 % 0 0 0 0 0 0

Weight of

bitumen - - 62.02 68.58 75.21 81.91 88.69

Total Weight

of sample

- - 1240.32 1246.88 1253.51 1260.21 1266.99

90

E) Dry & Washed-Sieve Analysis Test for SMA20



SMA20 mixture




Cumulative Weight

25 4.256 0 0 0 0 19 3.762 100 % 0 % 0 0

12.5 3.116 90% 10 % 120 120 9.5 2.754 70 % 20 % 240 360 4.75 2.016 24 % 46 % 552 912 2.36 1.472 20 % 4 % 48 960 0.6 0.795 14 % 6 % 72 1032 0.3 0.582 13.5 % 0.5 % 6 1038

0.075 0.312 9 % 4.5 % 54 1092 Pan 0 9 % 108 1200

∑ =100 % ∑ = 1200



Sample No. 1 2 Weight of sample before washing, A (g) 1092 1092 Weight of oven dry sample in air(after washing), B (g) 1072 1074.9 Amount of Dust coated on aggregate = A - B 20.0 17.1

Average =18.55gm

91

Percentage of required filler material for SMA20

Percentage of dust (Filler) = 9% (Ortdinary Portland Cement).

9 % OPC (Ordinary Portland Cement) = 0.09*1200 = 108gm.


Then, 108 - 18.55 = 89.5gm OPC that must be added to the total weight of aggregate.

Table A6.3: Final Aggregate gradation used to prepare Marshall samples for SMA20


Sieve Size

mm

% retained


agg.

@ 5.0 %

@ 5.5 %

@ 6.0 %

@ 6.5 %

@ 7.0 %

19 0 % 0 0 0 0 0 0

12.5 10 % 120 120 120 120 120 120

9.5 20 % 360 240 240 240 240 240

4.75 46 % 912 552 552 552 552 552

2.36 4 % 960 48 48 48 48 48

0.6 6 % 1032 72 72 72 72 72

0.3 0.5 % 1038 6 6 6 6 6

0.075 4.5 % 1092 54 54 54 54 54

OPC 7.45 % 1181.5 89.5 89.5 89.5 89.5 89.5 Added Dust 0 % - 0 0 0 0 0

Weight of

bitumen - - 62.18 68.76 75.41 82.14 88.93

Total Weight

of sample

- - 1243.68 1250.26 1256.91 1263.64 1270.43

92

3) Percentage of Bitumen Contents and Required weight of Asphalt for

different mixtures

The following formula is used to calculate the weight of bitumen required at

each asphalt content:

% Asphalt content = [ W bitumen / (W bitumen + W aggregate)] x 100

For example, at 5% asphalt content for ACW10, the required weight of asphalt is :

5% = [ W bitumen / (W bitumen + 1152)] x 100 → W bitumen =60.63gm.

Table A7.1: Weight of bitumen at each bitumen content for ACW10

Bitumen Content 5.0 % 5.5 % 6.0 % 6.5 % 7.0 %

Weight aggregate (gm) 1152 1152 1152 1152 1152

Weight of bitumen (gm) 60.63 67.04 73.53 80.08 86.70

Table A7.2: Weight of bitumen at each bitumen content for ACW14

Bitumen Content 4.5 % 5.0 % 5.5 % 6.0 % 6.5 %

Weight aggregate (gm) 1157.2 1157.2 1157.2 1157.2 1157.2


Table A7.3: Weight of bitumen at each bitumen content for ACB28

Bitumen Content 3.5 % 4.0 % 4.5 % 5.0 % 5.5 %



93

Table A7.4: Weight of bitumen at each bitumen content for SMA14

Bitumen Content 5.0 % 5.5 % 6.0 % 6.5 % 7.0 %



Table A7.5: Weight of bitumen at each bitumen content for SMA20

Bitumen Content 5.0 % 5.5 % 6.0 % 6.5 % 7.0 %



94

APPENDIX B

1) Bulk Specific Gravity of coarse and fine Aggregates

A) ACW10

Table B1.1: Bulk Specific Gravity of Coarse Aggregate

Sample 1 2 3 Weight Oven-dry aggregate, A (gm) 1045.3 1045.6 1044.50

Weight saturated surface dry aggregate, B (gm) 1056.9 1054.2 1053.70

Weight aggregate in water, C (gm) 650.7 651.7 650.00

2.573 2.598 2.587 Bulk Specific Gravity (S.G)bulk = A/(B-C) Average(S.G)bulk = 2.586

2.602 2.619 2.610 Bulk SSD Specific Gravity (S.G)ssd

= B/(B-C) Average (S.G)ssd = 2.610 2.649 2.654 2.648 Apparent Specific Gravity (S.G)app

= A(A-C) Average (S.G)app = 2.650

1.110 0.822 0.881 Water absorption (%) = 100(B-A)/A Average = 0.938 %

95

Table B1.2: Bulk Specific Gravity of Fine Aggregate

Sample 1 2 3

Pycnometer Weight 280.7 281.4 294.1

Weight of oven dry material, A (gm) 493.3 491.2 493.6

Weight of SSD aggregate , S (gm) 500.2 500.4 501.1

Weight of Pycnometer filled with water, B (gm) 875.5 877.1 878.4

Weight of Pycnometer with specimen and water to the calibration mark, C (gm)

1172.3 1184.7 1189.1

2.425 2.548 2.592 Bulk Specific Gravity (S.G)bulk =A/(B+S-C) Average(S.G)bulk = 2.522

2.459 2.595 2.632 Bulk SSD Specific Gravity (S.G)ssd =S/(B+S-C)

Average (S.G)ssd = 2.562

2.510 2.675 2.699 Apparent Specific Gravity (S.G)app =A/(A+B-C) Average (S.G)app = 2.628

1.399 1.873 1.519 Water absorption (%) =100(S-A)/A Average = 1.597 %

Specific Gravity of Blend

S.G (blend) =

(%coarse Agg./SG coarse) + (%fine Agg./SG fin e) + (%filler/SG filler)

S.G (blend) = 100

100

(35 / 2.586) + (63 / 2.522) + (2 / 2.98)

= 2.551

96

B) ACW14

Due to using the same source of aggregate for ACW10,ACW14 and ACB28,

specific gravity of coarse and fine aggregate have been considered to be the same for

the three mixtures which is 2.586 for Coarse aggregate and 2.522 for fine aggregate.


S.G (blend) = 100

(%coarse Agg./SG coarse) + (%fine Agg./SG fin e) + (%filler/SG filler)

S.G (blend) = 100

(44 / 2.586) + (54/ 2.522) + (2 / 2.98)

= 2.557

C) ACB28

Due to using the same source of aggregate for ACW10,ACW14 and ACB28,

specific gravity of coarse and fine aggregate has been considered the same which are

2.586 for Coarse aggregate and 2.522 for fine aggregate.


S.G (blend) = 100

(64 / 2.586) + (34/ 2.522) + (2 / 2.98)

= 2.570

97

D) SMA14

Table B1.3: Bulk Specific Gravity of Coarse Aggregate

Sample 1 2

Weight Oven-dry aggregate, A (gm) 995.4 995.9

Weight saturated surface dry aggregate, B(gm) 1005.3 1005.0

Weight aggregate in water, C (gm) 623.9 623.8

2.610 2.613 Bulk Specific Gravity (S.G)bulk = A/(B-C) Average(S.G)bulk = 2.611

2.636 2.636 Bulk SSD Specific Gravity (S.G)ssd = B/(B-C)


2.679 2.676 Apparent Specific Gravity (S.G)app = A/(A -C) Average (S.G)app = 2.678

0.995 0.914 Water absorption (%) = 100(B-A)/A Average = 0.954 %

Table B1.3: Bulk Specific Gravity of Fine Aggregate

Sample 1 2

Pycnometer Weight 293.3 -

Weight of oven dry material, A (gm) 495.2 -

Weight of SSD aggregate , S (gm) 500.4 -

Weight of Pycnometer filled with water, B (gm) 877.2 -

Weight of Pycnometer with specimen and water to the calibration mark, C (gm)

1194.7 -

2.707 - Bulk Specific Gravity (S.G)bulk = A/(B+S-C) Average(S.G)bulk = 2.707

2.736 - Bulk SSD Specific Gravity (S.G)ssd = S/(B+S-C)


2.787 - Apparent Specific Gravity (S.G)app = A/(A+B-C) Average (S.G)app = 2.787

1.050 - Water absorption (%) = 100(S-A)/A Average = 1.050 %

98

Specific Gravity of Blend for SMA14

100

S.G (blend) =

(%coarse Agg./SG coarse) + (%fine Agg./SG fin e)

S.G (blend) =

(68.5 / 2.611) + (31.5 / 2.707)

= 2.641

E) SMA20

S.G (blend) =

100

100

(%coarse Agg./SG coarse) + (%fine Agg./SG fin e)

S.G (blend) = 100

(76 / 2.611) + (24 / 2.707)

= 2.634

99

APPENDIX C

Maximum Specific Gravity of Loose Mixtures

A) ACW10

Table C1.1: Maximum specific gravity of loose ACW10 mixture

Sample 1 2 Asphalt content of the mix, ( % bit ) 6.00 6.00 Specific gravity of Aspahlt, S.G(bit) 1.03 1.03 Weight of Bowl in air, A (g) 2210.5 2210.8 Weight of Bowl in water, B (g) 1393.7 1393.7 Weight of Bowl & sample in air, C (g) 3426.0 3425.8 Weight of sample , D (g) 1215.5 1215.0 Weight of Bowl & sample in water, E (g) 2103.7 2101.8

Maximum specific gravity of Mix, Gmm (T.M.D) 2.405 2.397 =D/(D+B-E) Average = 2.401 Effective specific gravity of aggregate, S.G eff 2.628 2.619 =(100-%bit) / {(100/Gmm)-(%bit/S.Gbit)} Average = 2.6236

100

B) ACW14

Table C1.2: Maximum specific gravity of loose ACW14 mixture

Sample 1 2 Asphalt content of the mix, ( % bit ) 5.50 5.50Specific gravity of Aspahlt, S.G(bit) 1.03 1.03 Weight of Bowl in air, A (g) 2210.1 2210.3Weight of Bowl in water, B (g) 1393.7 1393.7Weight of Bowl & sample in air, C (g) 3815.3 3816.5Weight of sample , D (g) 1605.2 1606.2Weight of Bowl & sample in water, E (g) 2332.8 2333.9


C) ACB28

Table C1.3: Maximum specific gravity of loose ACB28 mixture



101

D) SMA14

Table C.4: Maximum specific gravity of loose SMA14 mixture

Sample 1 2 Asphalt content of the mix, ( % bit ) 6.00 6.00 Specific gravity of Aspahlt, S.G(bit) 1.03 1.03 Weight of Bowl in air, A (g) 2210.1 2210.1 Weight of Bowl in water, B (g) 1392.8 1392.7 Weight of Bowl & sample in air, C (g) 3728 3765 Weight of sample , D (g) 1517.9 1554.9 Weight of Bowl & sample in water, E (g) 2285.2 2300.2 Maximum specific gravity of Mix, Gmm (T.M.D) 2.427 2.402 =D/(D+B-E) Average = 2.414 Effective specific gravity of aggregate, S.G eff 2.657 2.625 =(100-%bit) / {(100/Gmm)-(%bit/S.Gbit)} Average = 2.641

E) SMA20

Table C.5: Maximum specific gravity of loose SMA20 mixture



102

APPENDIX D

MARSHALL MIX DESIGN RESULTS

1) ACW10

103

2) ACW14

104

3) ACB28

105

4) SMA14

106

107

107

5) SMA20

Documents

THE RELATIONSHIP BETWEEN MARSHALL STABILITY, FLOW