INFLUENCE OF FLAKY AGGREGATE TOWARDS CREEP AND...

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INFLUENCE OF FLAKY AGGREGATE TOWARDS CREEP AND

RESILIENT MODULUS ON ASPHALT CONCRETE 20

MOHD ZUL HANIF BIN MAHMUD

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

JANUARY 2013

Specially dedicated to my beloved father and mother,

Mahmud bin Doll and Begam binti Nebi

and my family,

Nur Faezah, Bibi Sygena, Bibita, Mohammed Gupta, Mohd Faisal and Nur Aliah

Bazilah

THANK YOU

ACKNOWLEDGEMENT

In the name of Allah, the Most Gracious and Most Merciful.

Alhamdulillah, praises to Allah for giving me the strength, patient, time and

wisdom to complete this thesis. This long awaited moment seems like a dream to me.

There have been many ups and downs while doing this project. Personally, I enjoyed

the moment doing the data collecting and experiments. It seems like a huge challenge

for me to choose the proper rock samples and doing the labs. I would give my sincere

appreciation to my beloved family for believing in me to be who I am today.

My deepest appreciation goes to my supervisors, Dr. Haryati bte Yaacob and

Dr. Ramadhansyah Putra Jaya for their guidance and help. Thank for all the

criticism and shared experiences to help me prepare this thesis. I would also want to

further my thanks to technicians of Highway and Transportation laboratories for their

assistance and cooperation.

Last but not least, I would like to thank my friends that gave their support and

ideas in this project and my time as a post-graduate student in UTM. May ALLAH

reward all of them for their kindness and sincerity. All the helps and sacrifices from

all parties are unforgettable and really appreciated. Hopefully one day, I may

continue to my study to a higher level. InsyaAllah.

ABSTRACT

The aim of this paper is to investigate and evaluate the characteristics of flaky

aggregate shapes that specifically towards creep and resilient modulus. The

maximum allowable aggregate size selected specifically for this study is size 20 mm.

In general, flakiness aggregates are being avoided in asphalt concrete mixture simply

because these types of properties have significant influence of towards gradation and

interlocking characteristic of the aggregate. Due to this significant influence of flaky

aggregate, it is recommended that the proportion of flaky aggregate should be

limited. Therefore, based on the Jabatan Kerja Raya (JKR) and Malaysian Standards

(MS), it specified that the maximum allowable flakiness should be less than 25% in

asphalt concrete mixture. This study is only focusing on asphalt concrete mixture that

consists of 10%, 20% and 30% proportion of flaky aggregate. The objective of this

study is to determine the relationship between resilient modulus against percentage

of flaky aggregates in the asphalt concrete mixture. This study also looks on the

influence different percentage of flaky aggregates towards dynamic creep properties

in a mixture. Hence, several tests like Marshall Tests, Resilient Modulus test and

dynamic creep test were conducted. Based on Marshall Tests, the optimum asphalt

content obtained for 10%, 20% and, 30% was 5.6%, 5.7% and 5.8% respectively.

The findings of this research are the value resilient modulus and stiffness modulus

decreases as the amount of flaky aggregate increases.

ABSTRAK

Tujuan kertas kerja ini adalah untuk mengkaji dan menilai ciri-ciri bentuk

batu baur yang berkeping khusus kepada daya tahan modulus dan rayapan. Saiz

agregat maksimum yang digunakan dalam projek ini dipilih secara khusus adalah

saiz 20 mm. Secara umum, batu baur perlulah dielakkan dalam campuran konkrit

asfalt kerana batu baur mempunyai pengaruh yang signifikan ke arah penggredan dan

sifat saling bertaut batu baur. Disebabkan oleh pengaruh ini, batu baur menjadi tidak

stabil. Oleh itu, nisbah batu baur tidak stabil harus dihadkan. Berdasarkan kepada

Jabatan Kerja Raya (JKR) dan Piawaian Malaysia (MS), penyerpihan maksimum

yang dibenarkan hendaklah kurang daripada 25% dalam campuran konkrit asfalt.

Kajian ini hanya memberi tumpuan kepada campuran konkrit asfalt yang terdiri

daripada 10%, 20% dan 30% perkadaran batu baur berkeping. Objektif kajian ini

adalah untuk menentukan hubungan antara daya tahan modulus terhadap peratusan

batu baur yang berkeping dalam campuran konkrit asfalt. Kajian ini juga mengkaji

pengaruh peratusan batu baur berkeping yang berbeza terhadap sifat dinamik rayap

dalam campuran. Oleh itu, beberapa ujikaji seperti Ujian Marshall, Ujian Daya

Tahan Modulus dan Ujian Rayapan Dinamik telah dijalankan. Berdasarkan Ujian

Marshall, kandungan optimum asfalt yang diperoleh untuk 10%, 20%, dan 30%

adalah masing-masing 5.6%, 5.7% dan 5.8%. Hasil kajian ini mendapati bahawa

nilai daya tahan modulus dan kekakuan modulus berkurangan apabila jumlah batu

baur yang berkeping bertambah.

TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF ABREVATIONS xiii

LIST OF APPENDIX xiv

1 INTRODUCTION 1

1.1 General 1

1.2 Problem Statement 2

1.3 Objectives of the Study 3

1.4 Scope of the Study 3

1.5 Significance of the Study 4

2 LITERATURE REVIEW 5

2.1 Shapes of Aggregates 5

2.2 Influence of Aggregate Morphological Characteristics 6

2.3 Marshall Mix Design 7

2.3.1 Stability 8

2.3.2 Flow 9

2.3.3 Air Void 10

2.3.4 Voids in Mineral Aggregate 11

2.3.5 Void Filled with Asphalt 13

2.4 Resilient Modulus 14

2.4.1 Previous Research on Resilient Modulus 16

2.5 Creep 17

3 METHODOLOGY 18

3.1 Introduction 18

3.2 Methodology Flow Chart 19

3.3 Source and Type of Materials 20

3.3.1 Aggregate 20

3.3.2 Binder 20

3.4 Aggregate Properties Test 21

3.4.1 Sieve Analysis 21

3.4.1.1 Dry Sieve Aggregate 21

(For Fine and Coarse Aggregate)

3.4.1.2 Washed Sieve Analysis 22

3.4.1.3 Gradation limits 24

3.4.2 Specific Gravity 25

3.4.2.1 Specific Gravity for Coarse Aggregate 25

3.4.2.2 Specific Gravity for Fine Aggregate 26

3.4.3 Flakiness Index Test 28

3.4.4 Aggregate Impact Test 30

3.5 Asphalt Physical Properties Test 32

3.5.1 Penetration Test 32

3.5.2 Softening Point Test 33

3.6 Marshall Mix Design 35

3.6.1 Marshall Specimen 35

3.6.2 Theoretical Maximum Density (Loose Mix) 37

3.6.3 Determination of Optimum Asphalt Content 39

3.7 Mechanical Properties of Asphalt Concrete 40

3.7.1 Resilient Modulus Test 41

3.7.2 Dynamic Creep Test 43

4 RESULTS AND DATA ANALYSIS 46

4.1 Introduction 46

4.2 Material Preparation 46

4.2.1 Aggregate Gradation 47

4.2.2 Specific Gravity and Water Absorption 48

4.2.3 Aggregate Impact Value 49

4.3 Determination of Marshall Properties 50

4.3.1 Theoretical Maximum Density 50

4.3.2 Optimum Asphalt Content 50

4.4 Mechanical Properties Analysis 52

4.4.1 Resilient Modulus 53

4.4.2 Dynamic Creep 55

5 CONCLUSION AND RECOMMENDATION 57

5.1 Introduction 57

5.2 Conclusion 57

5.3 Recommendations 58

REFERENCES 59

APPENDIX 63

LIST OF TABLES

TABLE NO. TITLE PAGES

Table 2.0 Test and Analysis Parameters for Asphalt Concrete 7

Table 2.1 Factors Affecting VMA on Hot Mix Asphalt (HMA) 12

Table 3.1 Gradation limits for Asphalt Concrete 20 24

Table 3.2 Maximum Difference Allowable In a Penetration 33

Table 3.3 Design Asphalt Contents 35

Table 3.4 Test and Analysis Parameters for Asphalt Concrete 40

Table 4.1 Flaky Aggregate Gradation 48

Table 4.2 Specific Gravity and Water Absorption for Each 49

Material

Table 4.3 Aggregate Impact Value 49

Table 4.4 Effective Specific Gravity for different 50

Percentage Flaky Aggregate

Table 4.5 Optimum Asphalt Content for Different 51

Portion of Flaky Aggregate

Table 4.6 Verification Sample for Different Percentage 52

of Flaky Aggregate

Table 4.7 Resilient Modulus Values with Different Percentage 53

of Flaky Aggregates

LIST OF FIGURES

NO.OF FIGURE TITLE PAGES

Figure 2.0 Aggregate Shape 6

Figure 2.1 Variation of Stability for Flakiness Indices 8

Figure 2.2 Variation of Flow for Flakiness Indices 9

Figure 2.3 Variation of Air Void for Flakiness Indices 11

Figure 2.4 Variation of Void in Mineral Aggregate for 13

Flakiness Indices

Figure 2.5 Variation of Void Filled with Bitumen for 13

Flakiness Indices

Figure 2.6 The relationship between Resilient Modulus 16

and Flaky Aggregate Content

Figure 3.0 Research Methodology Flow Chart 19

Figure 3.1 Thickness Gauge 29

Figure 3.2 Impact Testing Machine 31

Figure 3.3 Softening Point Test 34

Figure 3.4 Motorized Sieve Shaker 38

Figure 3.5 Resilient Modulus Test 42

Figure 3.6 Dynamic Creep Test 44

Figure 4.1 Aggregate Gradation Curve for AC 20 47

Figure 4.2 Resilient Modulus at 25oC with different 54

percentage of Flaky Aggregate

Figure 4.3 Resilient Modulus at 40oC with different 55


Figure 4.4 Stiffness Modulus values with different 56


LIST OF ABREVIATIONS

AASHTO - American Association of State Highway and

Transportation Officials

AC20 - Asphalt Concrete Wearing With 20 mm Nominal

Maximum Aggregate Size

ASTM - American Society for Testing and Materials

AASHTO - American Association of State Highway and

Transportation Officials

BS - British Standard

HMA - Hot Mix Asphalt

JKR - Jabatan Kerja Raya

MS - Malaysian Standard

TMD - Theoretical Maximum Density

VTM - Void Ratio in Mix

VFA - Void Filled Asphalt

VFB - Void Filled Bitumen

OAC - Optimum Asphalt Content

OBC - Optimum Bitumen Content

g - gram

mm - millimetre

KPa - KiloPascal

MPa - MegaPascal

N - Newton

ºC - degree celcius

% - percent

LIST OF APPENDIX

APPENDIX NO. TITLE PAGES

Appendix A Aggregate Size Distribution and Determination 64

of Filler

Appendix B Aggregate Proportion Distribution for Flaky 65

Aggregate

Appendix C Specific Gravity and Water Absorption of 66

Coarse and Fine Aggregate

Appendix D Aggregate Impact Value for Asphalt Concrete 20 67

Appendix E Softening Point of Asphalt Cement 67

Appendix F Penetration of Bituminious Materials 67

Appendix G Theoretical Maximum Density 68

Appendix H Marshall Properties Test 70

Appendix I Resilient Modulus 76

Appendix J Marshall Properties Test 91

CHAPTER 1

INTRODUCTION

1.1 General

Aggregates are one of the major materials that are used in any road

constructions. Generally, testing the properties of aggregates is one of the major

concerns in asphalt industry because aggregates testing will give information about

that particular research, design or mixture in order to implement quality control in

any constructions projects. The aggregates samples that are tested will represent and

reflects the average quality of the entire mass of the materials. For this paper, the

major focus is to evaluate on the influence of flaky aggregate in an asphalt concrete

mixture in terms of mechanical properties.

The shapes of the aggregates play a significant influence towards the

performance of asphalt pavements. There are many shapes of aggregates. It can be

classified as round, cubical, flaky, elongated, irregular and etc. For road construction,

the shapes of flaky aggregates are commonly undesirable and therefore the amount

flaky aggregate should be limited. Research have indicates that aggregate testing

towards the characteristic like particle size, shapes and texture will influence the

performance and life span of the asphalt pavement (Brown et al. 1989). According

to the Malaysian Standards (MS 30) manuals, the amount of maximum flakiness

allowed can be varies from 25 % to 30 % depending on the type of road layers. For

asphalt concrete, the maximum amount of flaky aggregate allowed is 25%.

1.2 Problem Statement

Aggregate shapes play a significant role influencing the performance of

asphalt concrete mixture since 95% of the composition of hot mix asphalt is consist

by mineral aggregate. The shapes of the aggregates that are used in many

constructions can be rounded, irregular, angular, flaky, elongated and also a

combination of flaky and elongated. In most road construction, flaky and elongated

aggregates are undesired shaped since these types of aggregate have higher chances

to be broken once the road constructed and opened to public. Oduroh et al. (2000)

described the orientation of the flaky and elongation shape of the aggregate in an

asphaltic mixture creates lower resistance towards shear deformation and thus,

creates problems like premature failure and decreasing the performance of the

pavement.

It is understood that flexible pavement is the most common type of pavement

used in the world. According to Satyakumar & Wilson (2009), most of the authorities

used Marshall Tests to judge the mechanical properties asphalt mixture which is used

in pavement design. They continue to explain that the value of Marshall Tests cannot

be directly used in pavement design calculation due to the increase traffic demand

and load. It is important to understand the mechanical properties to measure

resistance to deformation and failure. One of the tests to measure flexibility of

asphalt mixture is through Resilient Modulus (MR) test. This test is being carried out

using universal testing machine to understand the effectiveness of the elastic

properties of the mixture of asphalt under repeated loading. Erol et. al. (2005)

discussed in his study that by using a more irregular morphologies can improve the

resilient modulus of the bituminous mixture. For this study, the second type of

mechanical testing for asphalt pavement is creep test. This test is to measure time

dependent deformation under constant compressive stress for the asphalt concrete

mixture.

1.3 Objective of Research

The main aim of this research is to investigate the influence of different

proportion of flaky shape aggregates in terms of mechanical properties for an asphalt

concrete mixture for size 20 mm (AC 20). The objectives of this study are also listed

below;

(i) To determine the relationship of different percentage of flaky aggregates

towards the resilient modulus properties in an asphalt concrete mixture;

(ii) To investigate the influence different percentage of flaky aggregates towards

dynamic creep properties in an asphalt concrete mixture.

1.4 Scope of Study

The scopes of study on this research are focusing on the influence flaky shape

aggregates towards creep and resilient modulus for an asphalt concrete mixture. The

scope of study is listed as follow;

i. This study is focused on asphalt concrete size 20 mm (AC 20);

ii. This research involved different proportion of 10%, 20% and 30 % flaky

shapes aggregate in an asphalt concrete mixture;

iii. The scope of this study for this project are involved with the influence of

exceeding the maximum allowable proportion of 25% of flaky shapes

aggregate in an asphalt concrete mixture;

iv. For this study, the laboratory tests that are conducted to obtain the objective

of this research i.e. Marshall Tests, indirect tensile test and dynamic creep

test.

1.5 Significance of Research

This study will help to develop an understanding toward the influence

different shapes aggregates in an asphalt concrete mixture in Malaysia. Below are the

other significant influences towards this research:

(i) To understand the behaviour of different proportion flaky shapes aggregate

based on resilient modulus and stiffness modulus in an asphalt concrete mixture;

(ii) To assist in improving better understanding of proper shapes of aggregates in

order to provide a more sustainable pavement development in Malaysia.

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