FACTORS INFLUENCING THE STRENGTH OF FOAMED …eprints.utm.my/id/eprint/40541/5/MohdYazipMatoriMFKA2013.pdf · Adalah didapati kekuatan campuran bitumen buih dari segi modulus, mampatan

FACTORS INFLUENCING THE STRENGTH OF FOAMED BITUMEN STABILISED MIX

MOHD YAZIP BIN MATORI

UNIVERSITI TEKNOLOGI MALAYSIA

FACTORS INFLUENCING THE STRENGTH OF FOAMED

BITUMEN STABILISED MIX

MOHD YAZIP BIN MATORI

A thesis submitted in fulfilment of the

requirements for the award of the degree of

Master of Engineering (Transportation and Highway)

Faculty of Civil Engineering Universiti Teknologi Malaysia

JANUARY 2013

iii

To my beloved Wife, Habibah Bt Ahmad, Son Muhammad Hyqal and Daughter Hyda Yazmin.

iv

ACKNOWLEDGEMENT

Alhamdullilah, deepest gratitude to Allah S.W.T, for his willing in giving me

opportunity and strength to complete this study.

I would like to express my deepest gratitude to my supervisor, Professor Dr

Mohd. Rosli bin Hainin for his guidance, assistance and moral support throughout

the period of the study. Suggestion and constructive comments given by him are

gratefully acknowledged. Special thanks to all staff of Pavement Laboratory,

Kumpulan Ikram Sdn.Bhd for their assistance and guidance.

Great thanks and heartfelt acknowledgments are expressed to my family for

their encouragement, patience and sacrifice from the beginning until the end of my

study. I am sincerely thankful for their understanding throughout my study,

especially during the difficult time.

Last but not least I would like to acknowledge each and every person who has

contributed to the success of this report, whether directly or indirectly.

v

ABSTRACT

Recycling of asphalt pavements has increased significantly since 1970 and in

Malaysia the use of foamed bitumen as stabilizing agent was first introduced in year

2001. Recycling of asphalt pavements involves mixing of existing pavement material

with stabilizing agent such as foamed bitumen, bitumen emulsion, cement or lime

and placed on the milled pavement and compacted. Although the asphalt pavements

recycling with foamed bitumen as stabilizing agent is gaining recognition and

acceptance as a cost effective method of rehabilitating distressed pavement, so far in

Malaysia no study has been carried out on the characteristic of foamed bitumen

stabilized mix. The strength of foamed bitumen stabilized mix is influenced by

factors such as cement content, moisture level and curing time. This study evaluates

the effect of ordinary Portland cement as active filler, curing time and moisture

content on the strength properties of foamed bitumen stabilized mix. Foamed

bitumen treated samples with different RAP proportions were tested for their strength

properties at various active filler contents, curing time and moisture contents. It was

found that the strength in terms of resilient modulus, Unconfined Compressive

Strength (UCS) and Indirect Tensile Strength (ITS) values, increased with curing

time and percentage of active filler. It was also found that the maximum strength in

terms of resilient modulus, Unconfined Compressive Strength (UCS) and Indirect

Tensile Strength (ITS) was not at Optimum Moisture Content (OMC) and the

strength decreased as the RAP proportion increased.

vi

ABSTRAK

Kitar semula pavemen telah berkembang dengan pesat sejak tahun 1970 dan

di Malaysia penggunaan bitumen buih sebagai ejen penstabil telah pertama kali

diperkenalkan pada tahun 2001. Kitar semula pavemen melibatkan proses

mencampur ejen penstabil seperti bitumen buih, bitumen emulsi, simen atau ‘lime’

dengan lapisan pavemen sediada, di baur, diturap semula dan kemudiannya

dipadatkan. Walaupun kitar semula pavemen meggunakan bitumen buih sebagai ejen

penstabil telah mendapat pengiktirafan dan diterima sebagai kaedah yang kos efektif

untuk membaiki kerosakan jalan, namun setakat ini tiada kajian yang telah

dijalankan mengenai ciri ciri campuran ini di Malaysia. Kekuatan atau prestasi

campuran bitumen buih dipengaruhi oleh beberapa factor seperti kandungan simen,

kandungan RAP, kandungan lembapan dan masa awet (curing). Kajian yang

dijalankan ini menilai kesan kandungan RAP, kandungan simen, kandungan

lembapan dan masa awet (curing) terhadap kekuatan campuran yang distabil dengan

bitumen buih. Adalah didapati kekuatan campuran bitumen buih dari segi modulus,

mampatan dan riceh bertambah dengan bertambahnya masa awet (curing) dan

adanya kandungan simen. Didapati juga kekuatan maksima bagi modulus, mampatan

dan riceh tidak berlaku pada kandungan lembapan yang optima. Kekuatan campuran

juga menurun dengan bertambahnya kandungan RAP.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION OF THE STATUS OF THESIS

SUPERVISOR’S DECLARATION

TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xii

LIST OF ABBREVIATIONS xiv

LIST OF APPENDICES xv

1 INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 2

1.3 Objectives 3

1.4 Scope of the study 3

1.5 Significance of the study 4

2 LITERATURE REVIEW 5

2.1 Cold Recycling 5

2.2 Stabilizing Agent 6

viii

2.3 Foamed Bitumen 7

2.4 Foamed Bitumen Stabilised Mix 9

2.5 Property of Aggregate and Reclaimed Asphalt Pavement (RAP) 11

2.6 Moisture Content and Density Relationship 13

2.7 Active Filler 15

2.8 Curing 16

2.9 Test for Foamed Bitumen Stabilised mix. 18

2.9.1 Unconfined Compressive Strength Test (UCS) 18

2.9.2 Indirect Tensile Strength Test (ITS) 19

2.9.3 Tensile Strength Ratio (TSR)/Moisture Susceptibility 20

2.9.4 Resilient Modulus Test 21

3 METHODOLOGY 22

3.1 Introduction 22

3.2 Sample Preparation 22

3.3 Sample Preparation for Foamed Bitumen Stabilised Mix 27

3.4 Sample Preparation for the effect of curing time 27

3.5 Sample preparation for the effect of moisture content 28

3.6 Sample Preparation for the effect of cement content 29

3.7 Materials 30

3.7.1 Reclaimed Pavement Samples 30

3.7.2 Existing Pavement Material 31

3.8 Laboratory Testing 32

3.8.1 Aggregate Grading 32

3.8.2 Determination of MDD/OMC 33

3.8.3 Determination of the foaming characteristic of the bitumen 34

ix

3.8.4 Preparation of Samples for ITS/UCS and Resilient Modulus 37

3.8.5 Compaction, curing and testing procedure for ITSdry, ITS soaked and Resilient Modulus 39

3.8.6 Compaction, curing and testing procedure for UCS 42

3.8.7 Determination of Design Bitumen Content 45

3.8.8 Resilient Modulus Test 45

4 RESULTS AND ANALYSIS 48

4.1 Introduction 48

4.2 Effect of Variation of RAP 48

4.2.1 Grading Analysis 48

4.2.2 Maximum Dry Density and Moisture Content 50

4.2.3 Optimum Bitumen Content 51

4.3 Effect of Variation of Curing Time on Mix 52

4.3.1 Effect on UCS 52

4.3.2 Effect on ITSdry 53

4.3.3 Effect on ITSsoaked 54

4.3.4 Effect on Resilient Modulus 55

4.3.5 Effect on Tensile Strength Ratio 56

4.4 Effect of Variation of Moisture Content on Mix 57






4.5 Effect of Variation of Cement Content on Mix 62


x





4.6 Summary of Findings 66

5 CONCLUSION AND RECOMMENDATION 69

5.1 Conclusions 69

5.2 Recommendations 70

REFERENCES

APPENDICES

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Interpretation of ITS tests 20

3.1 Experimental Matrix of the Study 25

4.1 Sieve analysis result of RAP/Crusher Run proportion 49

4.2 Results of MDD and OMC 50

4.3 Result of Optimum Binder Content 51

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Schematic of the Foamed Bitumen Production 8

2.2 Dispersion of foamed bitumen particles 10

2.3 Aggregate grading zones for foamed bitumen 11

2.4 Cutting drum operation in up-cutting direction 12

3.1 Works Flow Chart 24

3.2 RAP and Crushed Aggregate proportion 30

3.3 Reclaimed Asphalt Pavement (RAP) 31

3.4 Crushed Aggregate (CR) 31

3.5 Apparatus for aggregate grading 32

3.6 Vibrating Hammer method 33

3.7 Moisture content and dry density relationship 34

3.8 Half Life/ Expansion ratio 36

3.9 Foamed bitumen laboratory plant and mechanical mixer 38

3.10 100mm diameter ITS specimens 40

3.11 Curing of ITS specimen 40

3.12 ITS Test 41

3.13 Soaked specimen 42

3.14 Mould for UCS test 43

3.15 150mm diameter UCS specimen 43

3.16 UCS test 44

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3.17 Measured ITSdry, ITSsoaked, Density and TSR versus Foamed Bitumen Content. 45

4.1 Results of Grading Analysis 49

4.2 Dry Density and Moisture Content relationship 50

4.3 Optimum Binder Content at various RAP contents 51

4.4 Relationship between UCS and curing time at various RAP contents 52

4.5 Relationship between ITSdry and curing time at various RAP contents 53

4.6 Relationship between ITSsoaked and curing time at various RAP contents. 54

4.7 Relationship between Resilient Modulus and curing time at various RAP contents 55

4.8 Relationship between Tensile Strength Ratio (TSR) and curing time at various RAP contents. 56

4.9 Relationship between UCS and moisture content at various RAP contents 57

4.10 Relationship between ITSdry and moisture content at various RAP contents 58

4.11 Relationship between ITSsoaked and moisture content at various RAP contents 59

4.12 Relationship between Resilient Modulus and moisture content at various RAP contents 60

4.13 Relationship between Resilient Modulus and moisture content at various RAP contents 61

4.14 Relationship between UCS and cement content at various RAP contents 62

4.15 Relationship between ITSdry and cement content at various RAP contents 63

4.16 Relationship between ITSsoaked and cement content at various RAP contents 64

4.17 Relationship between Resilient Modulus and cement content at various RAP contents 65

4.18 Relationship between Tensile Strength Ratio (TSR) and cement content 66

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LIST OF ABBREVIATIONS

ACWC Asphaltic Concrete Wearing Course.

ACBC Asphaltic Concrete Binder Course.

RAP Reclaimed Asphalt Pavement.

C/R Crusher Run.

OMC Optimum Moisture Content.

MDD Maximum Dry Density.

ITS Indirect Tensile Strength test.

UCS Unconfined Compressive Strength test.

TSR Tensile Strength Ratio.

RM Resilient Modulus test.

CR Cold Recycling.

CIPR Cold In Place Recycling.

HMA Hot Mix Asphalt.

REAM Road Engineering Association Malaysia.

PF Percentage of Fine

BC Binder Content.

OBC Optimum Binder Content.

MMC Moisture Mixing Compaction.

BSM Bituminous Stabilised Mix.

xv

LIST OF APPENDICES APPENDIX TITLE PAGE

A Summary of Test Results – 100% RAP 76

B Summary of Test Results – 75% RAP + 25% CR 77

C Summary of Test Results – 50% RAP + 50% CR 78

D Summary of Test Results – 25% RAP + 75% CR 79

E Summary of Test Results – 100% CR 80

F Effect of curing time on UCS and ITSdry 81

G Effect of curing time on ITSsoaked and Resilient Modulus 82

H Effect of curing time on Tensile Strength Ratio (TSR) 83

I Effect of cement content on UCS and ITSdry 84

J Effect of cement content on ITSsoaked and Resilient Modulus 85

K Effect of cement content on Tensile Strength Ratio (TSR) 86

1

CHAPTER 1

INTRODUCTION

1.1 Background

Recycling of asphalt pavements has increased significantly since 1970. In

Malaysia the cold recycling technique which involved in-plant recycling or in-situ

recycling with foamed bitumen was first introduced in 2001. Since then the

technique has become popular as a viable alternative pavement rehabilitation

measure. The technique involves milling of existing pavement, mixed with the

stabilizing agent and placed on the milled pavement and compacted. The most

common stabilizing agents used for cold recycling in Malaysia are foamed bitumen,

bitumen emulsion, cement and lime. The cold recycling process is carried out either

in plant or in situ using purposed built recycling machine and recycled layer will

form a new road base stabilized layer. It is a normal practice in Malaysia to overlay

the newly stabilized roadbase layer with 60mm thick of binder course and 50mm

thick of wearing course layers.

Although the cold recycling technique with foamed bitumen is gaining

recognition as a cost effective method of rehabilitating distressed pavement, so far in

Malaysia no study has been carried out on the characteristic of foamed bitumen

stabilized mix. The performance of the recycled asphalt layer depends on the

proportion of reclaimed asphalt pavement (RAP), types of stabilizing agents, and

amount of cement [1]. Therefore, the purpose of this study is to evaluate in the

2

laboratory the effects of RAP, moisture content, curing time and cement to the

strength properties of foamed bitumen stabilized mix.

1.2 Problem Statement

A number of cold recycling projects with foamed bitumen stabilised mix

have been completed in Malaysia for the past 10 years and on-going performance

monitoring are in progress. However, despite such progress, option on foamed

bitumen has been limited because of the lack of a standardized mix design,

construction procedure and gaps that exist between the current knowledge and the

knowledge that is needed to increase the probability of success when using this

technology, particularly in the Malaysian hot and wet environment.

Important factors for the success of cold recycling works include site

investigation, evaluation of existing materials, laboratory mix design and

construction by appropriately skilled contractors. Before the cold recycling project

start, representative samples from the existing pavement are obtained and samples

are prepared to simulate as close as possible the property of material to be achieved

during the actual recycling process, but it must be also noted that the mix design

process or procedure cannot fully simulate what will happen in the field at the time

of construction. Because of inconsistency of pavement layer thickness and moisture

content from the existing pavement, field adjustments are sometime necessary, such

as increasing water or stabilizing agent content.

This experimental laboratory works simulate the on- site condition of the

foamed bitumen stabilised mix and the study is therefore aimed to answer problems

with regard to the effect of RAP, cement content, curing time and moisture content to

the strength properties of foamed bitumen stabilised mix. Among the problems faced

during the construction of a cold recycling project are;

i. Proportion of RAP and the existing unbound material is not consistent, as

the pavement layer thicknesses vary from place to place.

3

ii. During construction, it is difficult to meet the optimum moisture content

(OMC) and maximum dry density (MDD) target, existing moisture

content at the site normally varies from place to place.

iii. Before the recycling commences, cement in powder form is spread

manually based on pre-determined percentage required. During

construction the quantity or percentage of cement will vary because of

the cement being blown away by the movement of heavy traffic and by

strong wind.

iv. After the completion of recycling works, the determination of the

appropriate curing time before foamed bitumen stabilised layer can be

opened to traffic or be paved with asphaltic layer ACBC and ACWC

depends on the judgment of the contractor based on previous experience.

1.3 Objectives

The objectives of this study are:

i. To investigate the effect of cement, moisture content and curing time at

varying RAP proportions to the strength of foamed bitumen stabilised

mix.

ii. To analyse and compare the results obtained with the requirement of the

National Specification for Roadworks.

iii. To provide recommendations on the required cement content, moisture

content and curing time for foamed bitumen stabilised mix based on the

findings of the research.

1.4 Scope of the Study

The scope of the study covers the strength test for the foamed bitumen stabilised

mix and the study is limited to the evaluation of the specimens prepared in the

laboratory. The scope of this study is as follows:

4

i. To review and research the literature relating factors influencing the

strength of foamed bitumen stabilised mix.

ii. Development of work flow chart and experimental test matrix for the

study.

iii. Preparation of test specimens in accordance with prescribed procedures.

For the purpose of this study the materials used are limited to;

RAP from Grand Saga mill and replace project.

Aggregate (CR) from Kajang Rock Quarry.

Bitumen Penetration Grade 80/100 from SHELL.

iv. Investigation and laboratory testing on the strength of the foamed bitumen

stabilised mix and the laboratory tests carried out are as follows:

Unconfined Compressive Strength test (UCS).

Indirect Tensile Strength test (ITS) at dry and soaked condition.

Determination of Tensile Strength Ratio (TSR).

Resilient Modulus Test (RM).

v. Analysis of the test results and evaluating the strength properties of the

foamed bitumen stabilised mix.

vi. Findings, conclusion and recommendation from this study for further

research.

1.5 Significance of the Study

Although the cold recycling technique with foamed bitumen is gaining

recognition and acceptance as a cost effective method of rehabilitating distressed

pavement, so far in Malaysia no study has been carried out to study the characteristic

of foamed bitumen stabilized mix. Very little local data is available and the results

and output of this study can be used for the development of standard specification

and guidelines for cold recycling with foamed bitumen in Malaysia.

72

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Documents

FACTORS INFLUENCING THE STRENGTH OF FOAMED …eprints.utm.my/id/eprint/40541/5/MohdYazipMatoriMFKA2013.pdf · Adalah didapati kekuatan campuran bitumen buih dari segi modulus, mampatan