STUDY ON PERFORMANCE OF FLAT AND ELONGATED AGGREGATE

N LOW TRAFFIC ROAD

NUR SYAZWANI B1NTI MD ZAKI

A thesis submitted in partial fulfillment of the

requirements for the award of the degree of

Bachelor of Civil Engineering

Faculty of Civil Engineering & Earth Resources

Universiti Malaysia Pahang

NOVEMBER 2010

ABSTRACT

Aggregate are the largest amount of material that can be found in HMA.

Aggregates make up between 80% to 90% of total volume or 94% to 95% of the

mass of hot mix asphalt (HMA). With this facts, it is totally agree that aggregate

properties are very important in HMA because it will affect the performances of

the HMA. The objectives of this research are to evaluate the performances of the

pavement using flat and elongated aggregate as the main material and to

compare the strength of using flat and elongated aggregate in pavement mixes

for low traffic road with the normal mixes. During the first stage, the aggregates

were tested in order to know the characteristic. The test that had been done were

AIV Test, ACV Test, LA Abrasion Test, Flakiness Index and Elongation Index.

The bitumen also had been tested with the Penetration Test and Softening Point

Test. After that, the mixtures were designed and prepared. The mixtures were

designed as ACW14 and were tested in accordance with the JKR

Specification:Arahan Teknik Jalan. 15 samples were prepared using Marshall

Mix Design methods in order to determine the optimum asphalt content (OAC).

The second stage of the research was to evaluate the performances of the

mixture consist of flat and elongated aggregates. 12 samples were prepared with

different percentage of flat and elongated aggregate which is 0% as the standard

mixture, 20%, 40% and 60% as the experimental mixture. Based on the results,

it is observed that flat and elongated aggregate might implies a significant effect

on the performance of the mixtures. Thus, it can be concluded that the flat and

elongated aggregate can be used in pavement mixtures but the percentage of

aggregate must be limited to certain level to make sure the strength

characteristics of the mixes can be maintained.

V

ABSTRAK

Batu baur merupakan bahan yang mempunyai jumlah terbesar di dalam

campuran tar panas. Batu baur mewakili antara 80% ke 90% daripada isipadu

atau 94% ke 95% daripada berat campuran tar panas. Dengan fakta mi, ianya

telah dipersetujui bahawa ciri-ciri bath baur adalah sangat penting di dalam

campuran tar panas kerana ia akan memberi kesan kepada prestasi campuran tar

panas. Objektif kajian mi dijalankan adalah untuk menilai prestasi jalan yang

mengandungi bath baur yang leper dan memanjang sebagai antara bahan utama

dan untuk membandingkan kekuatan jalan yang mengandungi bath baur yang

leper dan memanjang untuk jalan yang rendah aliran trafik dengan campuran

biasa. Path peringkat pertama, bath baur telah diuji untuk mengetahui ciri

cirinya. Antara ujian yang telah dijalankan ialah ujian MV, ACV, LA Abrasion,

indeks keleperan dan indeks pemanjangan. Bitumen juga turut diuji dengan i.jian

penetrasi dan ujian titik kelembutan. Selepas itu, campuran jalan di reka dan

disediakan. Campuran telah direka sebagai ACW14 dan telah diuji mengikut

spesifikasi JKR:Arahan Teknik Jalan. 15 sampel telah disediakan menggunakan

kaedah rekabentuk campuran Marshall untuk menthpatkan kandungan tar yang

optimum. Peringkat kedua dalan kajian mi adalah untuk menilai prestasi

campuran yang mengandungi bath baur yang leper dan memanjang. 12 sampel

telah disediakan dengan perathsan bath baur yang leper dan memanjang yang

berbeza iaitu 0% sebagai campuran piawai, 20%, 40% dan 60% sebagai

campuran kajian. Berdasarkan keputusan, didapati bahawa bath baur yang leper

dan memanjang telah memberikan kesan kepada prestasi campuran. Oleh itu,

konldusinya bath baur yang leper dan memanjang boleh digunakan di dalam

campuran jalan tetapi peratusan bath baur mestilah dihadkan kepada satu tahap

untuk memastikan ciri-ciri kekuatan campuran tersebut boleh dikekailcan.

VI

TABLE OF CONTENT

CHAPTER TITLE PAGE

TITLE i

DECLARATION

DEDICATION

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENT vii

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF ABBREVIATIONS / SYMBOLS xvi

LIST OF APPENDIX xvii

WDUCTION 1

Introduction 1

Background 2

1.2.1 Flexible Pavement 3

1.2.2 Aggregate Shape and Surface Particles 5

Problem Statement 7

Objectives 8

Scope of Study 8

Significant of study 9

MI

J1Ti

1.1

1.2

1.3

1.4

1.5

1.6

VIII

2 LITERATURE REVIEW 10 2.1 Introduction 10 2.2 Hot Mix Asphalt 11

2.2.1 Physical Properties of Asphalt 11 2.3 Asphalt Cement 13 2.4 Aggregate 14

2.4.1 Classes of Aggregate 18 2.4.2 Aggregate Strength 19 2.4.3 Flat and Elongated Aggregate 20

2.5 Summary 21

3 METHODOLOGY 22 3.1 Introduction 22 3.2 Evaluation of Aggregate Physical Properties 24

3.2.1 Aggregate Impact Value Test 24 3.2.2 Aggregate Crushing Value Test 26 3.2.3 LA Abrasion Test 28 3.2.4 Flakiness Index 30 3.2.5 Elongation Index 31

3.3 Evaluation of Asphalt 32 3.3.1 Penetration Test 32 3.3.2 Softening Point Test 34

3.4 Marshall Mix Design 36 3.5 Analysis of Asphalt Mixture 38

3.5.1 Density and Void Analysis 38 3.5.2 Resilient Modulus Test 40

3.5.3 Marshall Stability and Flow Test 41 3.6 Summary 42

ix

4 RESULT AND DATA ANALYSIS 44 4.1 Introduction 44 4.2 Analysis on Aggregate Physical Properties 45

4.2.1 Aggregate Impact Value Test 45

4.2.1.1 AIV Test Result for Standard 45

Aggregate

4.2.1.2 AIV Test Result for Flat and 47

Elongated Aggregate

4.2.2 Aggregate Crushing Value Test 48

4.2.2.1 ACV Test Result for 48

Standard Aggregate

4.2.2.2 ACV Test Result for Flat 50

and Elongated Aggregate

4.2.3 LA Abrasion Test si

4.2.3.1 LA Abrasion Test Result 51

for Standard Aggregate

4.2.3.1 LA Abrasion Test Result for 52

Flat and Elongated Aggregate

4.2.4 Flakiness Index and Elongation Index 53

4.3 Bitumen Performance Result 54 4.3.1 Penetration Test 54

4.3.2 Softening Point Test 55

4.4 Determining Optimum Asphalt Content 55 4.4.1 Resilient Modulus 56

4.4.2 Bulk Density 57

4.4.3 Void jn Total Mix 58

4.4.4 Marshall Stability 59

4.5 Analysis of JIMA Characteristics using Flat 61

And Elongated Aggregate

4.5.1 Result of Resilient Modulus 61 4.5.2 Result of Bulk Density 62

4.5.3 Result of Marshall Stability 63

4.5.4 Result of Void in Total Mix 64 4.5.5 Result of Void in Mineral Aggregate 65 4.5.6 Result of Void Filled with Asphalt 66 4.5.7 Result of Flow 67 4.5.8 Result of Stiffness 68

4.6 Comparison Between Standard 69 Pavement Mixture and Experimental

Pavement Mixture

4.6.1 Resilient Modulus 69 4.6.2 Bulk Density 70 4.6.3 Void in Total Mix 71 4.6.4 Marshall Stability 72 4.6.5 Void in Mineral Aggregate 73

4.6.6 Void Filled with Asphalt 74 4.6.7 Flow 75 4.6.8 Stiffness 76

4.7 Summary 77

5 CONCLUSION AND RECOMMENDATION 78 5.1 Introduction 78 5.2 Discussion on result of pavement mixtures 79

consist of flat and elongated aggregate

5.2.1 Resilient Modulus 79 5.2.2 Bulk Density 80 5.2.3 Marshall Stability 80 5.2.4 Void in Total Mix 81 5.2.5 Void in Mineral Aggregate 82 5.2.6 Void Filled with Asphalt 82 5.2.7 Flow 83 5.2.8 Stiffness 83

5.3 Discussion on the Comparison Between 84 Standard Pavement Mixture and

X

Experimental Pavement Mixture

5.3.1 Resilient Modulus 85

5.3.2 Bulk Density 85

5.3.3 Void inTotal Mix 86 5.3.4 Marshall Stability 87 5.3.5 Void in Mineral Aggregate 87 5.3.6 Void Filled with Asphalt 88 5.3.7 Flow 89 5.3.8 Stiffness 89

5.4 Conclusion 90 5.5 Recommendation 91 5.6 Summary of Research 91

REFERENCES 92

Xi

APPENDIX

LIST OF TABLES

TABLE NO. TITLE PAGE

4.1 AW Test result for standard aggregate 45 4.2 MV Test result for flat and elongated aggregate 46 4.3 ACV Test result for standard aggregate 48 4.4 ACV Test result for flat and elongated aggregate 49 4.5 LA Abrasion Test result for standard aggregate 50 4.6 LA Abrasion Test result for flat and elongated 51

Aggregate

4.7 Flakiness and Elongation Index result 52 4.8 Penetration Test result 53

4.9 Softening Point Test result 54

4.10 PWD Standard Specification for Road Works 60

XII

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 Flexible pavement layer 4

2.1 Flat and elongated particles 20 3.1 Flow chart for laboratory work and analysis 23 3.2 Impact test machine 25 3.3 AIV sample 25

3.4 Compressing testing machine 27 3.5 ACV sample 27 3.6 LA Abrasion test machine 29 3.7 Flakiness sieve 30 3.8 Elongation index test 31 3.9 Flat ang elongated aggregate 31 310 Automatic penetrometer 33 3.11 Asphalt sample 33 3.12 Softening point test apparatus 35

3.13 Asphalt sample 35 3.14 Sample for determining optimum asphalt content 37 3.15 Marshall stability and flow test 42 4.1 Resilient modulus for standard mixture 50 4.2 Bulk density for standard mixture 51 4.3 Void in total mix for standard mixture 52

4.4 Marshall stability for standard mixture 53 4.5 Resilient modulus for experimental mixture 56 4.6 Bulk density for experimental mixture 57

4.7 Marshall stability for experimental mixture 58

XIII

xiv

4.8 Void in total mix for experimental mixture 59

4.9 Void in mineral aggregate for experimental 60

mixture

4.10 Void filled with asphalt for experimental mixture 61 4.11 Flow for experimental mixture 62 4.12 Stiffness for experimental mixture 63 4.13 Comparison of resilient modulus between 64

standard and experimental

4.14 Comparison of bulk density between standard 65

and experimental

4.15 Comparison of void in total mix between standard 66

and experimental

4.16 Comparison of marshall stability between standard 67

and experimental

4.17 Comparison of void in mineral aggregate between 68

standard and experimental

4.18 Comparison of void filled with asphalt between 69

standard and experimental

4.19 Comparison of flow between standard and 70

experimental

4.20 Comparison of stiffness between standard and 71

experimental

LIST OF ABBREVIATIONS /SYMBOLS

AASHTO American Association of State Highway and Transport Officials

ACV Aggregate Crushing Value

MV Aggregate Impact Value

ASTM American Society for Testing and Materials

BSI British Standard Institution

cm centimetre

d bulk density

g gram

9/cm3 gram per centimetre cube

G mb Bulk specific gravity

Gse effective specific gravity of the mix

Gb specific gravity of asphalt content

Gnm maximum theoretical specific gravity of the mix

bulk specific gravity of the aggregate

HMA hot mix asphalt

kg kilogram

kN kilo newton

kPa kilo pascal

kg/mm kilogram per milirnetre

LA Abrasion Los Angeles Abrasion

LVDT Linear Variable Differential Transducers

MATTA Material Testing Apparatus

MPa mega pascal

mm/min milimetre per minute

m metre

mm milimetre

rATJ

ms milisecond

N newton

PWD Public Work DepartmeniljKR

Pb asphalt content, percent by weight of the mix

rpm rotation per minute

TMD maximum theoretical density

VFA void filled with asphalt

VMA void in mineral aggregate

VTM void in total mix

WD mass of specimen in air

WSSD surface dry mass

WSUB mass of specimen in water

% percentage

°C degree Celcius

xvi

LIST OF APPENDIX

APPENDIX NO. TITLE

A Marshall Test Result for 5.0% and 5.5% of percentage bitumen

B Marshall Test Result for 6.0% and 6.5% of percentage bitumen

C Marshall Test Result for 7.0% of percentage bitumen

D Marshall Test Result for 0% and 20% of flat and

elongated aggregate

E Marshall Test Result for 40% and 60% of flat and

elongated aggregate

F Resilient Modulus Test Result for 0% of flat and

elongated aggregate

G Resilient Modulus Test Result for 20% of flat and

elongated aggregate

H Resilient Modulus Test Result for 40% of flat and

elongated aggregate

I Resilient Modulus Test Result for 60% of flat and

elongated aggregate

xvii

CHAPTER 1

INTRODUCTION

1.1 Introduction

Highway plays an important role in the development and sustainability of

human civilization from ancient times to the present. Today, throughout the world,

highways dominate the transportation system and providing access of natural

resources, retail marketing, industrial production, human population and to connect

between two towns (Mannering et a!, 2009). Highway transportation also gives a

big influence on the economic, social and political. In the twenty-first century, the

role of highway continues to evolve and investments in highway infrastructure have

been made continuously. But, highways require maintenance and rehabilitation at

regular interval. Thus, there is a strong emphasis in developing a new ways to

more economically construct and extend the life of the new facilities and to

effectively combat an aging highway infrastructure (Mannering et a!, 2009).

Pavements are among the costliest item associated with highway

construction and maintenance. In Malaysia, there are 74 603 km of road length

comprises in Semenanjung Malaysia, Sabah and Sarawak. Some of the road in

Malaysia are not paved but are composed of either gravel or a stabilized material

2

consisting of an aggregate material bound together with a cementing agent such as

Portland cement, lime fly ash, or asphaltic cement. Malaysia's road system

comprises several types of roads which are highway/expressways, federal roads,

state roads and municipal roads. The roads are either be design and maintenance by

major concessionaries, federal government, state government or municipal council.

Pavement provides two basic functions. The first function of pavement is to

guide the driver and delineate the roadway by giving a visual perspective of the

horizontal and vertical alignment of the traveled path. The second function of

pavement is to support vehicle loads. These function is the reason why pavement

design is very important (Mannering et al, 2009).

1.2 Background

In flexible pavement, mineral aggregate constitutes approximately about

95% of hot mix asphalt (HMA) by weight Q.S. Chen et al, 2005). Coarse aggregate

is the dominant material in the mineral aggregate. One of the main characteristics in

aggregate is the shape and sizes. Shape is important for proper compaction, load

resistance and workability. This is supported by the research that had been done by

Brown et al. 1989, Kandhal et al. 1992 and Kim et al. 1992 where the research has

shown that aggregate characteristics such as particle size, shape and texture

influence the performance and service ability of hot mix asphalt pavement.

Generally, cubic-angular shaped particles with a rough surface texture are the best.

1.2.1 Flexible Pavement

Flexible pavements are so named because the total pavement structure

deflects or flexes under loading. A flexible pavement structure is typically

composed of several layers of material which is surface course consist of wearing

course and binder course, base course, sub-base and sub-grade (Mannering et al,

2009). Each layer receives the loads from the above layer, spreads them out, then

passes on these loads to the next layer below. Thus, the further down in the

pavement structure. a particular layer is, the less load (in terms of force per area) it

must carry. Flexible pavement is laid with hot mix asphalt (HMA) at the surface

layer. The flexible pavement surface layers components are :-

• Seal coat : seal coat is a thin asphalt surface treatment used to

waterproof the surface or to provide skid resistance where the

aggregates in the surface course could be polished by traffic and

become slippery. Depending on the purpose, seal coats might or

might not be covered with aggregate.

• Surface course the surface course is the top course of an asphalt

pavement and sometimes called wearing course. It is usually

constructed of dense graded HMA. It must be tough to resist

distortion under traffic and provide a smooth and skid-resistant

riding surface. It also must be waterproof to protect the entire

pavement and subgrade form the weakening effect of water.

3

• Binder course the binder course or sometimes is called the asphalt

base course, is the asphalt layer below the surface course. Asphalt

4

will be too thick if only be laid in one layer. Thus, binder course is

used. Binder course generally consist of larger aggregates and less

asphalt and does not require as high quality as the surface course.

Resulted in a more economical design.

. Tack coat and prime coat : a tack coat is a very light application of

asphalt, usually asphalt emulsion diluted with water and used to

ensure a bond between the surface being paved and the overlying

course. A prime coat is an application of low-viscosity cutback

asphalt to an absorbent surface, such as an untreated granular base

on which an asphalt layer will be placed. its purpose is to bind the

granular base to the asphalt layer. The difference between a tack coat

and a prime coat is that a tack coat does not require the penetration

of asphalt into the underlying layer whereas a prime coat penetrates

into the underlying layer, plugs the voids and form a watertight

surface.

;eal Coat f Surface Course

Tack Coat .1 Binder Course -

Prime Coat' Base Course

• Subbase Course

l Compacted Subgrade

Natural Subgrade

Figure 1.1 Flexible pavement layer

1.2.2 Aggregate shape and surface particles

Aggregates are the largest component of 1-JIMA, making up 80 to 85 percent

of the mixture by volume and roughly 95 percent of the mixture by weight.

Aggregate characteristics and quality are major factors in the performance of HMA.

Aggregate is one of the most important materials in flexible pavement design

besides asphalts as these two materials will direct effect to the strength of the

highway segment (Mannering et al, 2009).

Mixtures with crushed coarse aggregate with sharp, angular shapes will

usually have the greatest shear resistance and, hence, the highest resistance to

rutting Q.S. Chen et al, 2005). These materials create HMA mixtures with the

highest voids in the mineral aggregate (VMA). Coarse aggregate angularity is

defined as the percentage by weight of the aggregate with one or more fractured

faces according to American Society for Testing and Materials (ASTM) D5821.

Similar to coarse aggregate, crushed angular fine aggregate will usually have the

greatest shear resistance. The use of crushed angular fine aggregate typically

increases the mixture VMA. Fine .aggregate angularity is established by AASHTO

T304, Method A, which measures the percentage of air voids present in loosely

compacted aggregate that passes the 2.36 mm sieve

The percentage of flat and elongated particles in coarse aggregate is another

important aggregate parameter. Fiat and elongated aggregates are known to have

adverse effects on the performance and strength properties of bituminous paving

mixtures (Oduroh, P.K, 1999). Besides, it will also affect the workability which

may lead to low densification, fatigue cracking and decrease in the fatigue

resistance of the pavement. Flat and elongated aggregates are aggregates with the

thickness less than three-fifths of their dimension and length greater that one and

fourth fifth times their mean dimension. Flat and elongated particles of coarse

aggregates have a tendency to fracture more easily than other aggregate particles. It

6

can break during the construction process, changing the mixture gradation and the

overall mixture properties. Therefore, aggregate shape is one of the important

properties that must be considered in the mix design of asphalt pavements to avoid

premature pavement failure. The shape of the aggregates affects the particles

interlock which affects the rutting resistance of the HMA pavement (Mannering et

a!, 2009).

Soft aggregate has a greater tendency to break than hard aggregate (Oduroh,

P.K, 1999). Flat, slivered aggregate particles also have a tendency to lie flat in the

pavement, creating slippage planes and reducing aggregate interlock. The way in

which aggregate particles pack together for any given gradation is influenced by the

surface texture of the particles. Rougher texture generates more friction between

aggregate particles and the mixture therefore resists compaction. Hence, for a given

number of design gyrations, the mixture will not compact as much and the VMA

will be higher.

Smooth texture, by contrast, does not generate as much friction between

aggregate particles. For a given number of design gyrations, the mixture containing

smoother particles will compact more easily and the VMA will be lower. Typically,

crushed faces have more texture than uncrushed faces. In the case of gravel

aggregate, the uncrushed portion of the particles tends to have a smooth texture.

The greater the percentage of each individual particle surface area that is fractured,

the more surface texture that will be present. Usually, the more a gravel is crushed,

the more surface texture it will have. Particles with two crushed faces tend to have a

greater percentage of surface area with rough texture than will particles with only

one crushed face (Oduroh, P.K, 1999).

However, crushing will not always increase texture, because some

aggregates fracture with very smooth faces. For any given gradation, the density to

VA

which aggregate particles will pack is influenced by the shape of the particles.

Angular particles those with sharp, defined edge tend to produce mixtures with a

higher VMA than mixtures containing rounded particles. Cubical particles that

retain a sharp, angular edge tend to create a higher VMA than particles with

rounded edges. But in this case, the flat and elongated aggregate will be used as the

material in the mixture for a low traffic road.

1.3 Problem Statement

Pavements tend to distress after only a few years of construction.

Pavement's failure such as cracking, stripping, rutting and so on happens due to

traffic loading and some other causes like how well the mix is done and the quality

of the mixture. Cost of constructing the pavement is usually expensive. It also

consists of the cost of crush / round particles aggregate which is high. Meanwhile,

the cost of flat and elongated particle is cheaper than angular particle. So, in this

research, the angular particle in HMA is changed with the flat and elongated

particles. This research is conducted to test whether the flat and elongated

aggregate can be used in the pavement mixture or not. The alternative is also

designed to reduce the cost of low traffic pavement construction and to extend the

life of the new facilities besides to effectively combat an aging highway

infrastructure. Moreover, a better road can be designed for a low traffic road so that

the road user will have a better road quality in the future. But, if only the

characteristics and strength of the mixes meet the specification then the flat and

elongated particle can be used in the mix for low traffic road. That is why the

strength of normal mix and experimental mix is compared.

8

1.4 Objectives

The objectives of this research are to:

i. To evaluate the performance of pavement mixes designed using flat and

elongated material.

ii. To compare the strength of flat and elongated pavement mixes and standard

pavement mixes in accordance to specification for low traffic road.

1.5 Scope of Study

The limitation for the this pavement design is:

a. The design is only for low traffic road : For this case study, a specification

of low traffic road will be used as a guidelines in making comparisons on

pavement strength.

b. Using flat and elongated aggregate as one of the material : Flat and

elongated aggregates will be used to replace a small portion of coarse

aggregate having round and angular shaped. The percentage of flat and

elongated aggregate in each mixes are grouped into three different group

which is 0%, 20%, 40% and 60%. Flat and elongated aggregate will not

replace the whole amount of coarse aggregate but only a small part of it

while the rest of coarse aggregate will maintain using normal aggregate.

9

c. This design is only apply to HMA only: HMA is usually used for pavement

design for road in Malaysia.

1.6 Significant of Study

This research aims to create a new approach in pavement design by using

different type shape of aggregate. it is done in order to find a way to reduce the cost

of constructing a new pavement for certain area as it is known that constructing a

new pavement is a bit pricey. This research will allow for an explicit study on the

new approach in pavement design which may be useful to the Public Works

Department PWD) of the Ministry of Works Malaysia and the road engineer in

order to mitigate the problems that rise due to the construction of new pavement.

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

An economical and adequate design is one of the important element in

pavement design. An underdesigned pavement will fail prematurely and costing

more money for repairs (Asphalt Institute, 1989). It is therefore important to

recognize that the proper selection of aggregate is pertinent to the achievement

of the desired performance of bituminous paving mixtures (Oduroh, P.K, 1999).

The design of a pavement structure is very important because it directly affects

on the construction and maintenance of the pavement. A good design would give

a great benefit to the economy if the life of the road could be extended.