1. CHAPTER 1
INTRODUCTION
1.1
Background of study
The deterioration of surface roads is defined by the damage type of its condition of the
surface over time. The distress such as permanent deformation, cracking and
disintegration is classified as pavement surface defects. Flexible pavement distress modes
normally considered in the flexible pavement analysis and design is fatigue cracking,
rutting and low temperature cracking (Thompson and Nauman, n.d.). In this case study,
the focus is on rutting or permanent deformation because rutting is one of the common
pavement distresses happen in Malaysia which lead to lower riding quality for road users
and high maintenance costs. It describes that permanent deformation or rutting happens
as a consequence of continuous loading including heavy load which lead to progressive
accumulation of permanent deformation under continuous tire pressure. Rutting happened
in the form of longitudinal depression across the wheel path due to the continuous
application of axle loading.
The factors that contribute to the rutting are coming from the excessive traffic
consolidation in the upper layer of the pavement, plastic deformation due to the
inadequate mixture stability and also instability caused by stripping of asphalt binder
below the riding surface of the pavement (Ahmad et. al, 2011). It also stated that increase
in temperature will result in rutting increases even though the traffic loading is under
control and stability in HMA mixtures provided higher resistance against deformation
1

2. process under repetitive loading ( Hafeez et.al, 2010). In order to limit the rut depth at
the acceptable levels, careful attention must be made in surface layers and the subgrade.
The polymer modified binder in asphalt has been shown in improving the strength and
performance of the HMA pavement. Hence, binders such as latex and polyacrylate have
been selected in this case study to be used with Hot Mix Asphalt as a binder. The
comparison between modified asphalt and conventional asphalt also been made to see
their rutting performance. There are four tests commonly used in monitoring rutting
resistance of asphalt mixture such as repeated-load creep test, wheel tracking test, static
creep test, indirect tensile test and Simple Performance Test (SPT).
Many methods could be used in designing HMA mix, and the old methods are Marshall
and Hveem methods where these methods are used in the early 1940s until mid-1990s.
Research done by the Strategic Highway Research Program (SHRP) on asphalt binder
and asphalt mixture has introduced the new method called Superpave (Superior
Performing Asphalt Pavement). The Superpave Mix Design Method consist of a method
for specifying mineral aggregates and asphalt binders, mixing design for asphalt and a
procedure for analyzing and predicting the performance of the pavement. A major
difference between Superpave mix design and other design methods, such as the Marshall
ad Hveem methods, is that the Superpave mix design method mainly uses performancebased and performance-related characteristics as the selection criteria for the mix design
(Garber and Hoel, 2010)
2

3. 1.2
Problem statement
In recent years, the capacity on road increase since the increasing of vehicle ownership
and development of world transportation. This kind of situation may lead to higher traffic
volumes, traffic loads and tire pressure. These factors will increase pavement deformation
such as the rutting. In Malaysia, permanent deformation or rutting is a failure that usually
happens on flexible pavement. Rutting exists when the interlocking between aggregate
and bitumen not really strong and happen in the form of longitudinal depression in wheel
path. Another possible factor that causes rutting is improper mix design like the excessive
asphalt content and an insufficient amount of aggregate particles in mixtures. The
presence of rutting could reduce the serviceability life of the flexible HMA pavement and
lead to certain safety risks as well. Furthermore, rut can lead to car accidents because it
tends to pull a vehicle towards the rutted track as it is steered across the rut and it is also
may cause the hydroplaning of the vehicle during rainy day as water filled up the rut.
As road consumer, this study is significant in the sense of obtaining good quality of
pavement which provided long term road serviceability. It is necessary to provide
pavement which has good characteristics in term of durability, strength, moisture content
and air void that can resist the formation of surface deformation. There are two principle
solutions to construct a more durable pavement; first by applying a thicker asphalt
pavement which will increases the construction cost and secondly making an asphalt
mixture with modified characteristics (Moghaddam et.al., 2011). There are several
actions can be done in improving the HMA mixtures. One of action is using additives
such as polymer modified binder in hot mix asphalt to increase durability of pavement
3

4. structures because additives have abilities to captivate amount of distress imposed by a
continuous heavy traffic load. The aim of this study is to evaluate the rutting performance
on the HMA mix design using latex and polyacrylate thus, to determine the most suitable
modified binder to be used in order to minimize the rutting resistance on HMA pavement.
This study shows comparisons between three types of polymer modified binder on Hot
Mix Asphalt by using Superpave Design Method and evaluation of rutting performance
on those mixes.
1.3
Objectives
The main objective of this study is to evaluate the rutting performance on hot mix
asphalt using polymer modified binder. To achieve this aim, the following secondary
objectives must be carried out:
i.
To determine the rutting performance of Hot Mix Asphalt on Superpave mix
design using unmodified and polymer modified binder.
ii.
To compare the rutting performance of Hot Mix Asphalt on Superpave Mixtures
on unmodified and polymer modified binder.
1.4
Significant of Study
The total volume of vehicles on the road keeps increasing every year which cause the
pavement deformation such as rutting also increases. The existence of rutting is
dangerous for road user since it accumulates water in the wheel path and this may lead to
accidents and hydroplaning. Thus, it is necessary to improve pavement quality that can
minimize pavement problems such as pavement deformation, cracking and surface
4

5. defects. It is also important to extend the service life of the road pavement by minimizing
the rut depth and this can be done by improving the performance of asphalt mixture. The
usage of modified binder and non-modified binder in HMA mixture bring a huge impact
on performance of hot mix asphalt.So, the relationship between binder characteristics and
mix results were evaluated to see the binder performance in term of rutting.
From this study, the performance of rutting using control, latex and polyacrylate as a
binder on hot mix asphalt is observed through Asphalt Pavement Analyzer (APA)
machine.
1.5
Scope of Work
The focus of the study is to evaluate the rutting performance of polymer modified binder
in hot mix asphalt using Superpave Design Method through Asphalt Pavement Analyzer
machine. The comparison between modified asphalt and non-modified asphalt as binder
has been made to identify if the modified asphalt capable to strengthen the pavement
sample in term of rut resistance. In addition, the selection of suitable modified binder
against rutting can be done in this study. The specification used in preparing HMA
sample is Superpave mix design with NMAS 19mm. In this study there are 2 types of
polymer modified binder used which are latex and polyacrylate. The percentage of
polymer modified binder used in hot mix asphalt was 8% for latex and 6% for
polyacylates which these data are obtained from previous research work done by Atikah,
2013. The aggregates used in mix design is obtained from Blacktop Quarry in Jalan
Templer, Rawang, Selangor. The binder used is penetration grade 80/100 where it is
obtained from Port Klang. The performance of rutting on hot mix asphalt was monitor
5

6. through Asphalt Pavement Analyzer machine. In addition, the scope of the study also
covers the following:
i.
Desk study.
ii.
Materials selection for aggregates and binders.
iii.
To compact and test the HMA mixtures trial blends using the Superpave Gyrator
Compactor device.
iv.
Evaluation of rutting performance based on the compiled final design HMA
mixtures using the Asphalt Pavement Analyzer machine.
v.
Data analysis and result.
The general outline procedure of study was illustrated as shown in Figure 1.1.
6

7. Objective of the research
Literature review
Selection of material
(Aggregates and Asphalt Binder)
Preparation of HMA mix design sample at 7±0.5%
air void
Evaluation of Rutting Performance on the final compiled of Design Asphalt
Mixture using Asphalt Pavement Analyzer (APA) machine
No
Achieved
7±0.5% air
void?
Yes
Data Analysis and Result
Conclusion
Report Submission and Presentation
Figure 1.1: The Outline Procedure of the Research Study (HMA using Superpave method
and Asphalt Pavement Analyzer to evaluate the rutting performance)
7

8. CHAPTER 2
LITERATURE REVIEW
2.1
Introduction
In the late 1950’s, test on the rigid and flexible pavement in Ottawa, Illinois was
conducted by AASHO (American Association of State Highway Officials) to determine
and identify how traffic can contribute to the deterioration of highway pavements.
Through the information and data obtained, knowledge of designing pavement structure,
pavement performance, load equivalencies and climate effects could be improve and
expand. The results that obtained from the AASHO road test were used to develop design
guides of structural pavement including the AASHTO Guide for the Design of Pavement
Structures and develop empirical equations and calculations to be used for the design of
pavement structures.
Flexible pavement and rigid pavement are two types of pavement as shown in Figure 2.1.
The scope of this study is focusing on the flexible pavement. The surface of flexible
pavement must be high quality and strong enough in order to resist large axle loads and
high temperature. Thus, flexible pavement is constructed with layers of different
materials that the surface strength increase as move towards the surface (weakest layer on
the bottom and strongest layer at the surface). Traffic load distribution of flexible
pavement depends on the layered system over the subgrade. The layers of a flexible
pavement structure basically consist of hot mix asphalt (HMA) at the pavement surface,
with a stabilized base, base course gravel, and sub base course gravel. In Malaysia the
8

9. common flexible pavement structure normally consists of bitumen pavement, granular
road base, drainage sub-base and the subgrade (Hassan and Sufian, 2008). The design of
pavement structure must according to the Arahan Teknik (Jalan) 5/85 which is derived
from the AASHO Road Test.
Figure 2.1 Flexible and Rigid Pavement Cross Section
2.2
Asphalt
Asphalt mixtures basically formed through the combination of asphalt cement, fine
aggregates, coarse aggregates and other materials, which depend on the type of the
mixtures. There are three types of asphalt mixtures that usually used in pavement
construction which are hot-mix hot-laid asphalt mixture, hot-mix cold-laid asphalt
mixture and cold-mix cold-laid asphalt mixture.
Asphalt is a thermoplastic viscoelastic adhesive which acts as a glue. It softens slowly
and change the physical state from solid to liquid when heated. It is characterized by its
consistency at certain temperatures. Its relevant properties are its workability, strength,
durability, imperviousness and adhesion. Generally, the asphalt properties in term of
9

10. viscosity is should be in specified fluid in order to allow it easy to conduct during the
construction process and process of aggregates coat and wet. To avoid problem such as
fracture and crack the viscosity of asphalt must restrain high temperature exposure so that
it will not permanently deform through heavy traffic load and low pavement temperature.
Factors need to be considered during selection of asphalt penetration grade and types are
the climate of the construction area where the temperature of the atmosphere has to take
into account and type of construction to be applied. Asphalt can be classified into two;
unmodified asphalt and modified asphalt. It is not recommended to use unmodified
asphalt because it has a lower quality of resistance and formation of pavement distress
can be easily formed when repetitive and heavy load is passed through the pavement.
Chemical composition if asphalt also effecting the penetration grade of asphalt and it is
stated that the chemical percentage of pure asphalt is 80 to 88% of carbon (C), 0.5 to 10%
of oxygen (O2), 9 to 11% of hydrogen (H2) and 0 to 1% of Nitrogen (N2) .
2.3
Hot Mix Asphalt
Hot Mix Asphalt (HMA) is a common type of mix that broadly be used all over the
world. Basic materials in HMA are a combination of asphalt binder and aggregates which
is conducted through a specific design method such as Marshall, Hveem and Superpave.
In addition, criteria of selecting the HMA mixtures are based on the different coefficient
(Hafeez et. al, 2010). The special procedure of HMA is it must be heated first before
proceed to the next step. Besides that in HMA mix design asphalt binder and aggregates
are heated together in order to ensure that the asphalt in fluid form and the aggregates is
totally dry during coating the aggregates. The newest method in designing HMA is called
Superpave Mix design method.
10

11. 2.3.1
Basic Materials
2.3.1.1 Aggregate
Aggregate is one of the main materials in the industry of construction and
it contribute a large portion in the construction of an asphalt pavement.
American Society Testing Materials (ASTM) had describe aggregates as a
granular or coarse material in the composition of mineral such as crushed
stone, sand and gravel. It can form into compound materials such as
asphalt concrete and Portland cement concrete when it binds together with
a medium like water, bitumen, Portland cement and lime. Furthermore,
aggregate also used in constructing base and sub-base layers for rigid and
flexible pavements.
Aggregate is usually based from mineral composition and it can be either
natural or undergo mechanical process with the purpose of specific
applications. The natural aggregates are usually extracted or taking out
from the large formation of the rock by an open excavation. Basically, it is
categorized into three geologic classification of rock, which are igneous,
metamorphic and sedimentary.
Crushed stone, sand and gravel are three types of the aggregates. Crushed
stone also known as crushed rocks and mostly crushed stone is excavated
from the bedrock. The second type of rock is gravel, it is the result from
the erosion and destruction of bedrock and surficial resources. Gravel also
can be crushed, since it has a large contribution in constructing asphalt
11

12. pavement or bases. The formation of sand is either from the erosion of
bedrock or mechanically crushed.
2.3.1.2 Asphalt Binder
Binder or binder courses describe as a medium which acting as an
intermediate
paving
courses
in
Hot
Mixed
Asphalt
(HMA)
pavement.Modified binder such as polymer modified binder are
recommended to improve resistance of asphalt binder against rutting and
thermal cracking (Moghaddam, et al, 2011) Nowadays, the grading of
binder is base on the Performance Graded (PG) system in Superpave
research instead of previously method such as penetration and viscosity
test. Asphalt binders can have significant different characteristics within
the same grading category. Grading is more accurate and there is less
overlap between grades, tests and specifications are intended for asphalt
binders to include both modified and unmodified asphalt cements. Asphalt
binder tests for Superpave performance grading are as follows:
i. Rolling thin film oven;
ii. Pressure aging vessel
iii. Dynamic shear rheometer; and
iv. Bending beam rheometer.
12

13. 2.3.1.3 Mineral Filler
Mineral fillers have traditionally been used in asphalt mixtures to fill the
voids between the larger aggregate particles. Generally, the aggregate
material passing the No.200 sieve is referred to as filler. In ASTM D242,
mineral filler is defined as consisting of finely divided mineral matter,
such as rock dust, slag dust, hydrated lime, hydraulic binder, fly ash, loess,
or other suitable mineral matter. Other materials, such as carbon black and
sulfur, have been used primarily to modify asphalt binder properties, but
they do have a role as filler, also. Fillers may be used to:
i.
Fill voids and, hence, decrease the optimum asphalt content
ii.
Meet specifications for aggregate gradation
iii.
Increase stability and strength
iv.
Improve the bond between asphalt cement and aggregate
Mineral fillers have been used to largely fill in the voids between the
aggregate particles and to meet specified gradations for HMA.
2.4
Modes of Pavement Distress in Malaysia
2.4.1 Cracking
Through the research work done by Public Works Institute Malaysia (IKRAM)
has stated that the most common failed faces by asphaltic concrete is cracking as
shown in Figure 2.2. The asphaltic concrete road which is constructed for the first
time usually exposed to fatigue and top-down cracking while reflection cracks
13

14. tend to exists on the road that has done resurfacing before on the top cracked
surface (Hassan and Sufian, 2008).
Figure 2.2 Cracking failures that exist on the asphaltic concrete road
2.4.2 Top-down Cracking
In Malaysia, the common grade of asphalt use for asphaltic surface is PEN 80/100
as a binder. The process of making asphaltic concrete acquire heat apply 150 –
170 ˚C during the mixing process between hot aggregates and PEN 80/ 100
asphalt (Hassan and Sufian, 2008). According to JKR, the asphalt tends to
strengthen and become hard at the primary stage of the procedure, in storage,
during the process of mixing and in service. Top-down cracking is referred as the
external (surface) crack downwards propagation which happen when the
hardening process go deeper in the surface crack. Figure 2.3 shows the existence
of top-down cracking on the road.
14

15. Top-down cracking exists on the new constructed asphaltic concrete road due to
the thickness of the bitumen mix 5-10 micron which is thin. In addition, factors
such as improper design method and poor compaction causes higher void content
5 - 8 % during hardening process and lead to cracking existence (Hassan and
Sufian, 2008). Besides, ultra violet exposure and moisture content also contribute
to the distress of the asphaltic concrete road.
Figure 2.3 Top-down Cracking
2.4.3 Reflection Crack
The reflected crack shown in Figure 2.4 is a exist crack where had been reflected
toward the new layer of asphaltic concrete with 40mm overlay thickness in a
relatively short period. The rate of reflection crack depends on the sort of
magnitude and cracking of the surface road bonded to overlay, and the volume of
vehicle passes along the road after the construction (Hassan and Sufian, 2008).
Based on the research study, the 40 mm thickness overlays of asphaltic concrete
are unsuitable for rehabilitation of the asphaltic concrete road.
15

16. Figure 2.4 Reflection Crack
2.5
Rutting
Rutting is dangerous surface distress for road user where it causes accumulation of
surface water; hence it increases the possibility of hydroplaning and skidding (Hassan
and Sufian, 2008). Water that accumulates on the pavement distress during rain will
increase the water infiltration rate into the pavement layer and the existence of
deformation will cause the vehicle to lost control especially during lane changes which
both of these factors is dangerous for road users. Rutting also defined as longitudinal
cracking in road pavement where the presence of rutting will bring uncomfortable in
driving comfort for road user and affects safety and health. Rehabilitation is one of the
ways to overcome the permanent deformation problem and it must continuously apply on
the road after the road reach its service life. Figure 2.5 shows pictures of permanent
deformation or rutting.
16

17. Figure 2.5 Permanent deformations or rutting
2.5.1 Factors Affecting Rutting
Permanent deformation or rutting is categorized as a longitudinal depression
which is formed along the wheel paths. Figure 2.6 shows the rutting that happens
on the road. It happened due to the accumulation of minor deformations that
caused by high temperature and repetitive heavy loads. Factors that contribute to
deformations may be caused by too much continuous stress by tire being applied
to the subgrade or by an unstable asphalt mixture where shear strength of the
mixture is too low. In addition, rutting also considered as a structural problem. It
is generally the result happened because of wrong calculation during the
pavement design or of properties in the subgrade that has been weakened due to
the moisture intrusion. In the other research study, the presence of rutting is due to
the accumulated deformation happened in the asphalt surface layers rather than in
the subgrade layer. Incorrect procedure in preparing the asphalt mixture also
contributes to the permanent deformation. It is explained that when a layer of
17

18. asphalt pavement has inadequate shear strength it will cause shear deformation to
occur every time a heavy load such as truck passes through the pavement. A rut
will then appear after the asphalt pavement achieves the maximum load where it
can resist. This type of road distress can reduce the serviceability of the asphalt
pavement and the road user was exposed to a safety hazard.
Figure 2.6 Rutting or permanent deformation on the pavement
2.5.2 Laboratory Test Related to Rutting
2.5.2.1 Hamburg Wheel Tracker
The Hamburg Wheel Tracker (HWT) was developed and established by
Helmut Wind in Hamburg Germany. The advantage of HWT is it can
conduct the test of HMA beam and cylindrical sample in water.
18

19. The vertical load subjecting to the sample is 705 N and applied on a solid
rubber wheel. The diameter of loaded wheel is 194 mm and a width of 47
mm. The sample is compacted to an air void content of 7±1 percent, are
typically subjected to a maximum of 20,000 loading repetitive passes at a
rate of about 340 mm/s (Choubane et al, 1998). Figure 2.7 below shows
the Hamburg Wheel Tracker device.
Figure 2.7 Hamburg Wheel Tracking Device
2.5.2.2 Couch Wheel Tracker
The Couch Wheel Tracker (CWT) is modified version of Hamburg Wheel
Tracker. However in CWT tests only HMA beam samples being
submerged in the water (Choubane et al, 1998). Test samples are
subjected with a 705 N vertical load which is applied through a solid
rubber wheel. The rutting performance is determined by measuring the
19

20. height position of the loading wheel at the center of the travel span after
the process of continuous loading finish The measurements are constantly
recorded on a provided chart during the testing.
2.5.2.3 Georgia Loaded Wheel Tester
The development of Georgia Loaded Wheel Tester (GLWT) is from the
Georgia Institute of Technology at the Georgia Department of
Transportation in the mid-1980's (Choubane et al, 1998). It was designed
and planned with the aim of developing a simplified method to
enhancement the method of Marshall in evaluate the rutting characteristics
of the asphalt mixes which is used in Georgia. Figure 2.8 shows a
schematic drawing of one version of the Georgia Loaded Wheel Tester
Figure 2.8 Schematic drawing of one version of the Georgia Loaded
Wheel Tester
20

21. The advantages using GLWT is it capable of testing samples of the
confined asphalt concrete beam. It tests the samples of asphalt concrete
beam by using a stiff pressurized hose which is mounted at the top of the
specimens. The purpose of the hose was same as a tire which is to transfer
the load that is received from the loaded wheel directly to the beam
(Choubane et al, 1998). One complete loading cycle will involves back
and forth pass through of the loaded wheel. The rut depth is measured and
evaluated using a dial gauge that connected to the device and used a
reference template at set cycle intervals. The result then will be compared
to a pass or fail criteria.
2.5.2.4 LCPC (French) Wheel Tracker
The Laboratoire Central des Ponts et Chaussées (LCPC) wheel tracker
which is also known as Franch Wheel Tracker (FWT) majorly used in
France for more than a decade to determine rutting in HMA pavements
(Choubane et al, 1998). The function of LCPC is to carry out beam
sample test in the air. The samples will be subjected to 5,000 N loads
through a pneumatic tire which has been inflated to 600 kPa. The total
deformation depth of the slab is determined and recorded as the average of
a series of 15 measurements where three measurements is taken randomly
across the sample width at each of five points along the sample length.
The passing criterion for the sample is the average deformation depth must
less than 10 percent from the original sample thickness. Figure 2.9 shows
a France Wheel Tracker device
21

22. Figure 2.9 France Wheel Tracker device
2.6
Polymer Modified Asphalt
2.6.1 The Purpose of Asphalt Modification
Polymer modified Asphalt is asphalt which has undergone modification by
addition of modified binder such as latex and polyacrylates into the mix. The
advantages of using polymer modified asphalt are it has better performance in
durability, resistance and strength. Besides the physical properties of the asphalt
when added modified binder does not change the chemical nature of the asphalt.
Research done also stated that modified asphalt binders make the texture of the
mixture become soft and smooth at lower temperature which resulting in
reduction of thermal cracking. In addition to fatigue resistance of the asphalt
22

23. mixes is being improved with the polymer modified asphalt usage and since the
fatigue resistance of asphalt improves the pavement can resist more traffic load
and extreme climate temperature changes. Figure 2.10 shows the stress diagram of
unmodified asphalt and modified asphalt.
Shear stress ( )
Asphalt binders
Modified Asphalt
Large ‘c’
Unmodified Asphalt
Small ‘c’
Normal stress ( )
Figure 2.10 Stress Diagram of Modified and Unmodified Binder
2.6.2 Type of Asphalt Modifiers
Asphalt modifiers can be categorized in several ways which depends on the
mechanism where the modifier alters the asphalt properties, on the composition
and physical nature of the modifier itself, or on the properties of the target asphalt
that needs improvement or enhancement. A list of the types of modifiers
commonly used in the asphalt industry is given in Table 2.1. The modifiers are
classified based on the nature of the modifier and the generic types of asphalt
modifiers (National Cooperative Highway Research Program, 2001). The target
distress shown in the table corresponds to the main distress the additive is
expected, or claimed, to reduce. The information is based on an interpretation of
the published information for brands of modifiers that belong to the modifier
classes shown. The information in Table 2.1 indicates that asphalt modifiers vary
in many respects. They can be particulate matter or additives that will disperse
23

24. completely or dissolve in the asphalt. They range from organic to inorganic
materials, some of which react with the asphalt, while others are added as inert
fillers. The modifiers generically vary in their specific gravity as well as other
physical characteristics. They are expected to react differently to environmental
conditions such as oxidation and moisture effects.
Table 2.1 Generic types of asphalt modifiers currently used for paving applications
Effects on Distress
Modifier type
Fillers
Extenders
Polymers-Elastomers
Polymers-Plastomers
Crumb rubber
Oxidants
Hydrocarbons
Antistrips
Class
PD
Carbon black
Mineral: Hydarted lime
Fly ash
Portland cement
Baghouse fines
Sulphur
Wood lignin
Styrene butadiene di-block SB
Styrene butadiene triblock/ radial block (SBS)
Styrene isoprene (SIS)
Styrene ethylbutylene (SEBS)
Styrene butadiene rubber latex SBR
Polychloroprene latex
Natural rubber
Acrylorite butadiene styrene (ABS)
Ethylene vinyl acctate (EVA)
Ethylene propylene diene monomer (EDPM)
Ethylene acrylate (EA)
Polyisobutylene
Polyethylene (low density and high density)
Polypropylene
Different sizes, treatment and process
Manganese compunds
Aromatics
Napthenics
Paraffinics/ wax
Vacuum gas oil
Asphaltenes: ROSE process resins
SDA asphalteners
Shale oil
Tall oil
Polyamides
Hydrated lime
Organo-metallics
x
x
x
x
x
x
24
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
FC
LTC
MD
AG
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x

25. Fiber
Polyropylene
x
x
x
Polyster
x
x
Fiberglass
Steel
x
x
x
Reinforcement
x
x
x
Antioxidants
Carbon black
x
Calcium Salts
Hydarted lime
x
Phenols
Amines
x
PD: Permament Deformation
MD: Moisture Damage
FT: Fatigue Cracking
OA: Oxidative Aging
LTC: Low Temperautre Cracking
( National Cooperative Highway Research Program, 2001)
2.6.3 The Ideal Modified Binder
The most important property of asphalt when it is used in pavement construction
is changing in its stiffness with temperature. The ideal binder is necessary to be
hard and stiff enough at changes temperatures so that it can resist against
deformation and it also must be flexible enough at a lower temperature so as to
inhibit cracking. An ideal binder must exhibit the following properties:
i.
Adequate rigidity and inelasticity in order to minimize the rutting on a hot
day. In addition, it must have a progressive effect on the fatigue effect of
the bituminous hot mixture.
ii.
Flexible enough even during the cold temperature to avoid cracks such as
thermal cracks.
iii.
The binder must have light characteristics to allow the pumping process of
liquid binder smooth and fast and the binder is ideal when the viscosity
decreased to facilitate mixing and compaction of the hot bituminous
mixtures.
25
x
x
x
x
x

26. 2.7
Superior Performing Asphalt Pavement
Superior Performing Asphalt Pavement, better known as Superpave is a one of the
outcomes of the Strategic Highway Research Program (SHRP). SHRP target of
constructing the pavement requires less maintenance, provide a smooth ride, and is a
good value for tax payer’s money. The research was done in 1993, providing several new
elements in the system such as asphalt binder being graded by performance grade (PG),
consensus properties of aggregate, new mix design procedure, and mixture analysis
(National Cooperative Highway Research Program, 2001). Currently, the Superpave mix
design system has become the choice for the majority of transportation companies for
HMA mix design. The key equipment in Superpave method is the Superpave Gyratory
Compactor (SGC).
2.7.1
Background of Superpave
Through the development of asphalt mix design, there are now several different
types of laboratory compaction devices have been established in order to produce
specimens for volumetric and/or physical characterization (National Cooperative
Highway Research Program, 2001). Bruce Marshall and Francis Hveem are the
one whose developed mix design methods and by the late 1950s, these methods
were largely used in pavement construction. The Marshall mix design method
adopted the impact type of compaction while the Hveem mix design method uses
tampering blow and kneading compactor (Hafeez et. al, 2010).
The gyratory concept was credited to Phillipi, Raines, and Love of the Texas
Highway Department, which was a manual unit of gyratory pressing. In the
26

27. 1950’s, the concept was copied by John L. Macrae, with the U.S. Corps of
Engineers, developing a new device called gyratory kneading compactor, which
was named as the Gyratory Testing Machine (GTM) in 1993. Another important
contribution to the improvement of gyratory concept is through the Laboratory
Central des Ponts et Chausées (LCPC) in France, where it has a fixed external,
external mold wall angle of one degree with a compaction pressure to 600kPa.
2.8
Superpave Gyratory Compacter
The equipment used in the Superpave mix design method and which is the key piece is a
gyratory compactor as shown in Figure 2.11 which is the principle goals was to develop a
laboratory compaction method, which can consistently produce specimens representative
of in-service pavements. The Superpave Gyratory Compactor (SGC) compact HMA
sample to densities achieved under traffic loading conditions. Its ability to estimate
specimen density at any point during the compaction process is its key feature. Figure
2.11 shows Superpave Gyratory compactor.
Figure 2.11 Superpave Gyratory Compactor
27

28. 2.9
Asphalt Pavement Analyzer
The Asphalt Pavement Analyzer (APA) is the new version of the wheel tracker device
which is adapted from the Georgia Loaded Wheel Tester (Choubane et al, 1998). The
APA has implemented additional features which are installation of water storage tank and
is having the ability of testing both gyratory and beam samples. Generally, APA is a
wheel tracking device that applies a vertical load to a steel wheel (A Sholar and Page,
1999) Three beams or six gyratory of the samples can be performed and tested
simultaneously. The loaded wheels are applied to sample test of three pneumatic
cylinders, where each of it is equipped with standard aluminium wheels. The load from
each of the moving wheel is shifted and transferred to a test sample through a pressurized
rubber hose mounted along the top of the sample. The advantage of using APA is it can
evaluate not only the rutting performance of an HMA mixture, but it also can determine
the fatigue cracking and moisture susceptibility under certain condition of the service.
Figure 2.12 and Figure 2.13 shows an Asphalt Pavement Analyzer device and schematic
drawing of the device respectively.
Figure 2.12 Asphalt Pavement Analyzer Device
28

29. Figure 2.13 Schematic Drawing of the Asphalt Pavement Analyzer
29

30. 2.10
Gap of Research Study
Based on the studied journals, there are more focusing on evaluation of rutting
performance using different types of machineries used and gradation of aggregates. The
journal that using different type of machineries to evaluate the rutting performance such
as Simple Performance Test (SPT), Uniaxial Repeated Creep and Wheel Tracker Tests
were focused on determining the correlation of rutting performance using those
machines.
Besides that, a journal that used different types of aggregate gradation is to identify how
the size of aggregates can affect the performance of rutting. The study of aggregate
physical properties such as elongation and flakiness on rutting impact also was the main
focus of this journal.
On my research work, I’m focusing into the performance of polymer modified binder
against permanent deformation by comparing them with unmodified binder. There were
two types of polymer binder use of this work which are latex and polayacrylates.
Furthermore these two polymer modified binders were also comparable to each other to
select the best used of polymer against rutting. The criteria needed to be compared are the
rut depth which this was obtained through an Asphalt Pavement Analyzer. The result was
shown in term of graph and bar chart for better understanding of their performance on the
pavement. The characteristics of the polymer were analyzed and discussed to understand
why the performance of each polymer modified binder was differ from others polymer
modified binder. Table 2.2 shows a gap of research study.
30

31. Table 2.2 Gap of research study
Year
Title
Authors
Purpose
Finding
2011
Rutting
Evaluation
of
Dense
Graded
Hot Mix Asphalt
Mixture
Juraidah Ahmad,
Mohd Yusof Abdul
Rahman,
Mohd
Rosli Hainin
To investigate rutting
potential using SPT
dynamic modulus test
and how well this test
correlates with Wessex
wheel tracking test to
evaluate the rutting
potential of local HMA
The change in HMA
mixture behaviour
using SPT dynamic
modulus test was
effective
to
determine the rutting
potential
of the
HMA mix with
varying temperatures
and
loading
frequencies.
2010
Evaluation
of
Rutting in HMA
Mixtures Using
Uniaxial
Repeated Creep
& Wheel Tracker
Tests
Imran
Hafeez,
Mumtaz
Ahmed
Kamal
and
Muhammad
Waseem Mirza
To
predict
the
permanent deformation
of HMA mixtures at
elevated
temperature
with uniaxial repeated
creep and wheel tracker
test)
The specimen from
the wheel tracker
specimen test is
observed to produce
a less rate of
increase in rut depth
compared
to
unconfined uniaxial
repeated creep test.
2011
A
review
of Taher
Baghaee To review previous
fatigue
and Moghaddam,
studies
carried
on
rutting
Mohamed Rehan fatigue and rutting
performance of Karim and Mahrez properties of asphalt
asphalt mixes
Abdelaziz
concrete (AC) and the
effects of additives to
slow the deterioration
of asphalt mixture.
It was determined
that mixtures with
larger
aggregate
gradation and higher
asphalt content result
in lower the fatigue
life and slower the
presence of rutting
2012
Performance of Ashok
Pareek,
Polymer Modified Trilok Gupta and
Bitumen
For Ravi K Sharma
Flexible Bitumen
Shows
that
the
performance
of
polymer
modified
bitumen is better
than
conventional
bitumen PEN 60/70
31
To
investigate
the
performance
using
polymer
modified
bitumen
and
unmodified bitumen in
term
of
rutting
performance.

32. CHAPTER 3
RESEARCH METHODOLOGY
3.1
Introduction
In this chapter, the detail of progress work and the procedure of how this study was
conducted is explained. Before proceeding to the procedure of laboratory test,
information searching were collected to explore the background of the study. The aim of
this study is to evaluate the rutting performance of polymer modified binder in Hot Mix
Asphalt mix design. Thus, method and process to be used in determining the rutting
performance is listed in detail to achieve the aim of the study. The test is conducted
according to the required specifications, laboratory test procedure and information on the
materials used and also based on the sample properties. The method used in the sample
preparation is the Superpave Mix Design method. The sample mix involves for rutting
performance basically have two types of polymer modified binder which is latex and
polyacrylate. The result of the rutting performance of latex and polyacrylate was
compared and analyzed. After all process are fulfilled, the evaluation of routing
performance on the final compiled HMA sample was conducted through Asphalt
Pavement Alyzer machine. Figure 3.1 shows an illustration design of research studies.
Figure 3.2 shows the Overall Evaluation of Rutting Performance of Polymer Modified
Binder in HMA Mix Design.
32

33. Stage 1
Stage 2
Superpave Mix
Design Method
Desk
Study
Stage 3
Rutting Performance
Evaluation on Polymer
Modifed Binder in
HMA ;
-the specimen was
7±0.5% air void
Materials Collection for
the Project
1.
Blending of Specimen:
-Asphalt Pavement
Analyzer
-Unmodified Binder-Control
-Modified Binder- Latex at 160°C
and 1270 rpm
-Polyacrylate 140°C and 1650 rpm
1. Asphalt binder PEN
80/100
2. Aggregate of 19 mm
Control
nom. max size
3. Binderlatex
&
polyacrlates
Mixing of HMA mixture
-automatic mixer
Compacting and
Testing Samples with
Superpave Gyrator
Compactor
Figure 3.1 Design of Research Study
33
Result and Data
Analysis
Conclusion

34. Superpave Method
Material Collection
Asphalt binder PEN
80/100
Aggregate of 19 mm
nom. max size
Mixture Design
Compacting and testing with
Superpave Gyrator Compactor
Mathematical Calculation
Compiling and Establishing Final Blend Bituminous Paving Mixture
Evaluation Rutting on Compiled final Bituminous Paving
Mixture by Asphalt Pavement Analyzer
Conclusion
Figure 3.2 Overall Evaluation of Rutting Performance of Polymer Modified Binder
in HMA Mix Design
34

35. 3.2
Materials Selection
3.2.1
Asphalt Binder
The binder used in this research study is grade PEN 80/100 and based on the
current study, it also stated that asphalt binder is obtained from Port Klang. Type
of asphalt cement binders is classified based on their depth of penetration at
various temperatures. In Superpave mix design the selection of asphalt binder is
totally depends on climate which changes of temperature must be recorded and
traffic-loading conditions of the selected project location.
3.2.1.1 Softening Point
Softening point which also known as ring and ball test is a method to
determine the softening point of asphalt binders, in the range of
temperature of 30 °C to 150 °C. Two horizontal discs of asphalt binder,
cast in shouldered brass rings, are heated at a controlled rate in a liquid
bath while each supports a steel ball. The softening point is reported as the
mean of the temperatures at which the two discs soften enough to allow
each ball, enveloped in a asphalt binder which were control, latex and
polyacrylates to fall a distance of (25,0 ± 0,4) mm.
3.2.1.2 Ductility Test
The ductility of a asphalt material is measured by the distance in cm to
which it will elongate before breaking when a standard briquette specimen
of the material is pulled apart at a specified speed and a specified
35

36. temperature. Ductility is the property of bitumen that permits it to undergo
great deformation or elongation. In addition, ductility is defined as the
distance in cm, to which a standard sample of the material will be
elongated without breaking. The procedure of the ductility start by the
asphalt (control, latex and polyacrylate) were heated and poured in the
mould assembly placed on a plate. These samples with moulds are cooled
in the air and then in water bath at 27 °C temperature. The excess asphalt
was cut and the surface was leveled using a hot knife. Then the mould with
assembly containing sample is kept in a water bath of the ductility machine
for about 90 minutes. The sides of the molds are removed, the clips are
hooked to the machine and the machine was operated. The distance up to
the point of breaking of thread was the ductility value which is reported in
cm. The ductility value gets affected by factors such as pouring
temperature, test temperature and rate of pulling. The ductility value of the
control, latex and polyacrylate were then compared to determine the binder
properties between modified binder and unmodified binder.
3.2.1.3 Penetration Test
In this test, the consistency of asphalt was examined by determining the
distance in tenths of a millimeter that a standard needle vertically
penetrates into the bitumen specimen under known conditions of loading,
time and temperature. This is the most common methods of measuring the
consistency of a asphalt material at a given temperature. The modified
asphalt (latex and polyacrylate) and unmodified asphalt (control) were
36

37. examined together to determine the penetration value between the three
specimens.
3.2.2
Aggregates
Aggregates used in the asphalt mixture include various particle sizes which are
coarse and fine aggregates. Figure 3.3 and Figure 3.4 show the aggregate was
obtained from the Blacktop Quarry at Rawang and filled in the sack. The selection
of aggregates is necessary because it affects the performance of HMA mixes. The
preparation of aggregates can be classified into two properties; consensus
properties and source properties as shown in Table 3.1
Figure 3.3 Sample is taken from Blacktop Quarry, Rawang
37

38. Figure 3.4 Sample Filled in Sack
Table 3.1 Properties of aggregates
Consensus Properties
Source properties
a) Coarse aggregate angularity
a) Specify gravity
b) Fine aggregate angularity
b) Soundness
c) Flat and elongated criteria
c) Toughness
d) Gradation
3.2.2.1 Flat and Elongation
Flat and elongation particles defined as the percentage by mass of coarse
and granular aggregates that have a maximum to minimum measurement
ratio greater than five. This classification is used in the Superpave
requirement in purpose to identify aggregates that have a tendency to
obstruct compaction. Flat and elongated particles have a tendency to lock
up between particles more readily during compaction process which makes
the compaction more difficult.
38

39. 3.2.2.2 Toughness
Abrasion test is carried out to check the toughness property of aggregates
and to select whether the aggregates are suitable for different pavement
construction works. The Los Angeles abrasion test is a suggested one for
carrying out the toughness property. The standard of Los Angeles
abrasion test is to determine the percentage wear due to relative rubbing
and crushing action between the aggregate and steel balls used as a
medium to abrasive charge.
The Los Angeles machine comprises of round drum of internal diameter
of 700 mm and length 520 mm mounted on a horizontal axis to make it
rotated. The steel spherical balls of 48 mm diameters and weight 340-445
g were placed inside the machine together with the aggregates. The
number of the abrasion varies depending on the grading of the sample.
The quantity of aggregates to be used usually ranges from 5-10 kg. The
speed of the cylinder to rotate was 30-33 RPM for a total of 500 -1000
revolutions subject to the gradation of aggregates. After the desired
revolution was achieved, the material is sieved and passed fraction is said
as the percentage total weight of the sample. This value is called a Los
Angeles abrasion value. Figure 3.5 shows the Los Angeles Abrasion
Machine.
39

40. Figure 3.5 LA Abrasion Machine
3.3
Superpave Hot Mix Asphalt Design
The Superpave procedure was used to design the HMA mix used for the performance test
evaluation for this study. The design procedure is based on the percentage of asphalt for
the aggregate blends using the volumetric properties of the mix as the primary criteria.
These include a 4% air voids and a set of minimum values for the voids in HMA sample,
however HMA sample at 7% air voids were prepared for rutting performance test.
40

41. 3.3.1 Aggregates Preparation
The aggregates were oven-dried in oven in large quantity for at least 12 hours at a
temperature of 100° C as shown in Figure 3.6 and Figure 3.7, then the aggregates
are then left to cool at room temperature. The aggregates were then sieved and
separated into their individual particle sizes as shown in the table below. Table 3.2
shows the aggregate gradation for Superpave mixes.
Figure 3.6 Loose Aggregates Before Mixing
Figure 3.7 Oven
41

42. Table 3.2 Aggregates Gradation for Superpave Mixes
Sieve size
Blending Passing
% Retained
25
100
0.0
19
96
4.0
12.5
81.0
15.0
9.5
75.0
6.0
4.75
55.0
20.0
2.36
43.0
12.0
1.18
32.0
11.0
0.6
23.0
9.0
0.3
13.0
10.0
0.15
8.0
5.0
0.0075
4.0
4.0
(mm)
Pan
4.0
Total
100.0
Dust Loss After Wet Sieving
3.3.2 Polymer Modified Binder
The device used to mix the binder with polymer is a hot plate mixer as shown in
Figure 3.8. For the research study, the selected mix method to be used is a wet
method is used to mix with asphalt grade PEN 80/100 where the polymer
modified binder were weight using an electronic scale as shown in Figure 3.9 and
Figure 3.10 respectively. The binder parameter in the research study is shown in
Table 3.3 which is obtained through previous project done by Atikah (2013).
42

43. Figure 3.8 Hot Plate Mixer for Modified Asphalt
Figure 3.9 Modified Asphalt Preparation (Latex and Polyacrylate)
43

44. Figure 3.10 Electronic Weighing Scale
Table 3.3 Binder Parameter of Polymer Modified Binder Mixes
Optimum
Blending
Blending
Polymer Content
Temperature, °C
Velocity
Polyacrylate
6%
140
1650
Latex
8%
160
1270
Types of binder
44

45. 3.3.3 Preparation Process of Polymer Modified Binder
The preparation of polymer modified binder is shown in Figure 3.11
1. Measure
• The 500 g conventional binder is measure
• Heat the over at 120°C and put the binder inside oven
2. Heat
• Calculate the weight of polymer using
following equation;
•
𝑃
100
× 𝐴 = 500𝑔
… 1
• 𝑊𝑒𝑖𝑔𝑕𝑡 𝑜𝑓 𝑝𝑜𝑙𝑦𝑚𝑒𝑟 𝑚𝑜𝑑𝑖𝑓𝑖𝑒𝑑 𝑏𝑖𝑛𝑑𝑒𝑟 =
𝐴 − 500𝑔
… (2)
3. Calculate
• Which:
• P = 100% of mixture minus by
percentage of polymer modified binder
• A = weight of conventional binder +
polymer modified binder
• % of polymer modified binder is based on
the previous research work
4. Mix
• Mix the polymer modified binder using laboratory mixer based
on the mixing parameter as shown in Table 2.
Figure 3.11 Blending Procedure of Polymer Modified Binder
45

46. After finishing the mix process, the step was repeated with different percentage of
polymer modified binder which is 6% of Polyacrylate and 8%. Figure 3.12 shows
propeller mixer and the blade was used in mixing the binder and duration of
mixing was one hour and heated using an electric hot plate with temperature
control of laser temperature.
Figure 3.12 Mixing Process for Modified Asphalt
3.3.4 HMA Mixing Process
The aggregates and the modified asphalt were initially heated in the oven at a
temperature of 160ºC for about 2 hours as shown in Figure 3.13. The mixer also
switched on to heat up the mixer bucket. After 2 hours, the aggregates and the
46

47. modified asphalt were weighed according to their optimum binder content
percentage. Figure 3.14 shows the mixing process which took approximately 5 to
10 minutes to allow aggregates to be well coated with binder. Three samples of
aggregate weighing 2200g, 2300g and 2400g for each control sample with
modified asphalt were mixed and compacted in the first place in the Superpave
Gyratory Compactor. Another three samples of aggregates of weighing 1500g
were mixed to determine to maximum specific gravity (Gmm).Table 3.4 shows the
optimum binder content and
mix design properties obtained from previous
research (Atikah, 2013).
Figure 3.13 Heating of Aggregates and Binder
47

48. Figure 3.14 Heating of Aggregates and Binder
Table 3.4 Mix Design Properties
Mix property
DESIGN MIXTURE PROPERTIES
19mm NMAS mixture types
control
polyacrylate
latex
Criteria
Air voids%
VMA %
4.0
15.8
4.0
16.0
4.0
15.9
4
14 min
VFA %
Dust proportion%
%Gmm@ Nini=8
74.7
0.8
75.0
0.8
74.8
0.9
65-75
0.6-1.2
86.5
5.5
87.6
5.4
86.2
less than 89
5.3
(Source: Atikah,2013)
Asphalt Binder content
48

49. 3.3.5 Short Term Oven Aging (STOA)
All HMA mixes were short term aged in the oven for 2 hours at temperature of
140ºC to induce a short term oven aging (STOA). However, loose mix to
determine the maximum specific gravity was left at room temperature to cool as
shown in Figure 3.15.
Figure 3.15 Loose HMA mixture after mixed process
3.3.6 Compaction
The HMA samples are compacted in the Superpave Gyrator Compactor Device
(Figure 3.17) after STOA for two hours. Figure 3.16 shows the 150mm diameter
mould used to compact HMA sample. After compaction the sample allowed to
cool for 24 hours in room. The Bulk Specific Gravity (Gmb) was then determined
using buoyancy apparatus for each of the compacted HMA samples. From both
Gmm and the Gmb data, the percentage air voids for each control, latex and
49

50. polyacrylates samples are calculated. Figure 3.18 shows that the immersed
samples in water to determine the Gmb. A back-calculation formula was used to
identify the percentage of weight of sample needed for net performance test based
on 7% air void. The final HMA mixture aggregate is then mixed and compacted
and to the corresponding to Ndes gyrations.
Figure 3.16 Compaction Mould
50

51. Figure 3.17 Superpave Gyratory Compactor
Figure 3.18 Sample immersed in water
51

52. 3.4
Compacting and Testing HMA mixture of trial blend with Superpave Gyrator
Compactor Device
The Servopac Gyratory Compactor (SGC) is a device used to compact the HMA mixture
in mix design. It is capable to compact the HMA samples to a density which is required
in the field pavement. Basically, there are three main parameters that control the
compaction of the Superpave mix design which are vertical pressure, number of gyrations
and angle of gyration. For vertical stress it was set at 600-kPa, and the angle of gyration
was set at 1.25º, and lastly the number of gyrations, which is not being set up because it
may be various depending on condition of HMA samples. Three (3) samples for each
polymer modified binder and control were compacted at 1.25º in the Servopac Gyratory
Compactor to obtain the air void as shown in Figure 3.19.
Figure 3.19 Compacted HMA Sample
The procedure for sample preparation and testing in the Servopac started with weighing
the aggregates of 2200g, 2300g and 2400g respectively according to the required job mix
formula shown in Figure 3.20. The aggregate and asphalt binder for control, latex and
polyacrylates are preheated separately at 140ºC for about two hours then both are mixed
52

53. until the aggregates are fully coated with binder. The amount of binder used is based on
optimum binder content obtained from previous research conducted by Atikah, 2013.
The HMA mixture was then placed in the oven for two hours for short-term oven aging
(STOA). Prior to compaction in 150mm mold diameter and 65mm height. The three
samples were then compacted at 1.25º angle of the gyration.
Each specimen was left to cool at room temperature (approximately 25ºC) for at least 24
hours after the compaction process. The Bulk Specific Gravity of the specimen is then
determined using buoyancy balance apparatus. The maximum specific gravity of the
mixture was determined using Corelox machine and buoyancy balance apparatus. From
both Gmm and Gmb result obtained, the air void of the HMA samples was determined using
the following equation to achieve 7± 0.5% air void before proceeding with rutting
performance test.
𝐴𝑖𝑟
𝑜𝑖𝑑 = 100 × (1 −
Where,
A = bulk specific gravity (gmb)
B = theoretical maximum specific gravity (gmm)
53
𝐴
)

54. a) Aggregates- put into oven
with150°C - 160°C for more than
4 hours
b) Binder- put into oven with 150°C
at one – two hours
Heat both binder and
aggregates
The cynlinder mould is place into oven at
160°C for one – two hours
Heat cyclinder mould
The binder and aggregates is mix together
at 160°C to ensured the aggregates fully
coated with binder
Mix aggregates and binder
a) Place the mixes of aggregates and
binder into oven for two hours
(ageing process) at 160°C
b) Compact the HMA mixture using
SGC
c) Determine the specify gravity with
corelox
Gmb
a) Store at room temperature for 24
hours
b) Proceed with Corelok to get
specifc gravity
Gmm
Figure 3.20 Preparation Sample of HMA mixes
54

55. 3.5
Evaluation of Rutting Performance on HMA Mixture
Rutting or permanent deformation of the laboratory designed mixtures was evaluated
using the Asphalt Pavement Analyzer (APA) as shown in Figure 3.21. This wheel
tracking machine operates under a pair of wheels apply moving loads above two rubber
hose to the specimen in order to simulate the rutting performance in an accelerated
manner. The depth of depression or rut formed on the sample is measured and analyzed
using computer software. The test measures the depth and number of wheel passes to
failure. Each moving steel wheel of APA machine was 8 inches (203.6 mm) in diameter
and 1.85 inches (47 mm) wide.
The aggregates and asphalt mixtures were heated to 150°C, blended together then
returned to the oven for 2 hours before compaction. The HMA samples after the
compaction, is placed in the laboratory with room temperature at least for 24 hours to
allow the aggregates to uniformlly bind with the asphalt mixture . All samples were
compacted to reach target air voids of 7 percent to simulate the typical initial density in
the field. Figure 3.22 shows the set up the specimen.
55

56. Figure 3.21 Asphalt Pavement Analyzer Machine
Figure 3.22 Sample is placed in APA machine
For APA testing, eight cylindrical samples of which four are control samples, two latex
and two poly were compacted using Superpave Gyratory Compactor. The desired density
56

57. of HMA mixture was obtained by adjusting the weight of the mixture. Prior to real
testing, the sample was first conditioned in the APA chamber machine for two hours.
Testing on the APA machine was performed at 60°C with the sample sides in full
confinement and the pressure of rubber hose and wheel load was respectively set up at
690 kPa (100psi). The analysis of rut measurements was collected at 0, 25, 4000 and
8000 loading cycles. Figure 3.23 and Figure 3.24 shows the condition of the specimens
after the performance test.
Figure 3.23 Specimen condition after the test
57

58. Figure 3.24 Rut depth on the HMA sample
3.6
Data Analysis
In this study, the performance of pavement by using a polymer modified binder was
analyzed. The performance graph and bar chart are used to analyze the performance of
each polymer modified binder in terms of rut depth. The APA rut depth measurements as
collected during the performance test are summarized in result and discussion section.
The result was analyzed the effectiveness of rut potential of asphalt mixes between
polymer modified binder and control mixes.
58

59. CHAPTER 4
RESULT AND DISCUSSION
4.1
Introduction
This chapter discusses the results of laboratory HMA mix rut performances NMAS
19.0mm Superpave mixtures. The cylindrical samples were examined with respect to
rutting at three different mixtures which are control, latex and polyacrylate. Performances
of laboratory mixes were evaluated in terms of rutting by using the Asphalt Pavement
Analyzer machine. From this study, it determines that the design of hot mix asphalt
mixture using Superpave mix design suitable to be developed based on Malaysian
standard. The major steps in testing and analyzing process lead to the outcome of this
study.
4.2
Aggregates Properties Test
Three types of aggregates which are sand, screening and quarry dust were used in order
to developed aggregates blends meeting the requirements of gradation. The standard for
the consensus aggregate test is based on the traffic level and position the pavement layer.
The importance of the source aggregate property test is to estimate the specific stockpile
fraction. The toughness test by LA Abrasion is used to evaluate the percentage change in
coarse particle size of aggregates while aggregate soundness test capabilities to assess
both coarse and fine aggregates. Table 4.1 and Table 4.2 show results of consensus
properties and source properties respectively.
59

60. Based on the achieved result, the value for both consensus and sound properties is
satisfied and fulfilled the standard of mix design. Thus, the aggregates sample from
Blacktop Quarry,Rawang can be used in Superpave mix design.
Table 4.1 Consensus Aggregates Properties Result Blacktop Quarry, Rawang
Consensus Properties
References
Test Method
Result
Criteria
ASTM D 4791
Flat or Elongation in
Flakiness Index:
Coarse Aggregates
3.10%
<10 %
Elongation Index:
16.6%
<20%
Table 4.2 Source Aggregates Properties Result Blacktop Quarry, Rawang
Source Properties
References
Result
AASTHO T 96
Los Angeles Abrasion
Percentage of loss:
Test
4.3
Test Method
Criteria
25.35
<45 %
Binder Properties Test
Three test have been carried out to test the physical properties of asphalt which are
penetration test, softening point ad ductility test as shown in Table 4.3.
Table 4.3 Physical Properties of Aphalt
Conventional
Bitumen
Polyacrylate
(Modified)
Latex
(Modified)
Penetration value (mm)
85
60
55
Softening Point (ºC)
58
65
70
Ductility Test (cm)
95
125
150
60

61. Penetration test is a commonly adopted test on bitumen to grade the material in terms of
its hardness and it was used to measure the consistency of bitumen, so that the bitumen
can be classified into standard grades. In this work the penetration grade used were
80/100 where it means that the penetration value lies between 80 and 100. The
penetration value of bitumen helps to assess its strength between modified and
unmodified asphalt.
The greater value of penetration indicates softer consistency.
Generally higher penetration bitumen are preferred for use in cold climate and smaller
penetration bitumen are used in a hot climate area. In our climate we preferred lower
penetration grade to avoid softening due to the high temperature of the climate, and based
on the result it was said that modified asphalt has lower penetration value compared to
unmodified asphalt so the use of polymer modified binder in this work can be proceed to
the performance test.
Temperature is noted when the softened bitumen touches the metal plate
which is at a specified distance below. Based on the table 4.3, the lowest
temperature of softening point was 58 ºC using control sample. However the temperature
of softening point of where the ball fall was increased using latex and polyacrylates. The
difference of softening point may influenced by the properties of the asphalt binder.
Asphalt that consists latex has the highest softening point, where high temperature need
to soften the bitumen and same thing goes to polyacrylates specimen. Generally, the
higher softening point indicates lower temperature susceptibility and was
preferred in hot climates thus modified asphalt was showing positive results
in strengthening the HMA mixture for this work study.
61

62. Ductility is the property of bitumen that allows it to undergo elongation. In this work
asphalt binder are used in the HMA mixtures. It is important that bituminous material
forms ductile thin film around the aggregates that serves as a binder. From the table, the
modified binder has a longer ductility value which is 125 m and 150 cm for polyacrylates
and latex respectively compared to control. The binder material not of sufficient ductility
renders pervious pavement surface and leads to development of cracks. Therefore, the
longer the elongation of the bitumen can resist mean the better it can serve as a binder.
4.4
Evaluation of Rutting Performance using Asphalt Pavement Analyzer
The rut depth from APA at a number of wheel cycles was measured for control, latex and
polyacrylate sample to follow the rate of rutting for these samples. These are shown in
Figure 4.1 and Figure 4.2. It is observed that for all the samples, the APA rutting
accumulated at the end of 8000 cycles and it is measured within the first 25strokes whiles
about two-thirds of the rutting are mobilized at 4000 cycles. This may indicate that in
practice a greater portion cycles such as 4000 cycles of the entire rutting accumulated
within the pavement over its service period is likely to happen very quickly after the first
few months of traffic loading.
The higher the depth of rut indicates that the asphalt used in HMA mixture has lower
strength to against rutting in terms of the bonding with aggregates. This rut depth will be
in the form of densification rutting and it will not be dangerous enough to cause hazard,
but may be risky for motorist if it is deep enough and uneven across the pavement
surface. A very high rutting measured next the first few passes of cycles may seem to
have problem such as unstable mixture especially when the rutting does not begin to
stabilize during this level. This behavior of rutting was observed in the APA rutting for
62

63. the control sample, which explain that it has unstable mixtures. However, for the
purposes of comparison of the performance control sample and modified asphalt is to
determine the effect of rutting on polymer modified binder and also determined the best
modified asphalt (latex and polyacrylates) can be used to against rutting.
The HMA mixtures were tested with the Asphalt Pavement Analyzer (APA), which is
used as an indirect measure to predict rutting on the field. The mould diameter HMA
samples used were 150mm cylindrical and were compacted to approximately 7% air
voids. The sample was placed and maintained at a temperature of 60ºC in the APA
chamber for at three hours before the test started. Two replicates for each mixture were
tested for 8000 numbers of wheel cycles and the computer software will measure and
averages the rut depths. Figure 4.3 and Figure 4.4 shows the rut depths at the end of 8000
cycles, and other modified asphalt such as latex and polyacrylates.
The APA rut depths obtained from the rutting test show that polymer modified binder
which using latex is the most resistant to rutting with an average rut depths of 5.1mm.
The modified asphalt with polyacrylates average rut depth is 6.5mm while the control
sample is 8.00 mm. Therefore, polyacrylate was considered as more resistant to rutting
compared with control samples. This shows that the polymer modified binder with latex
is the most resistant to rutting followed by polymer modified binder with polyacrylate.
This could be concluded that the properties of unmodified binder was not strong enough
in binding with aggregates compared to the binding properties of modified asphalt with
aggregates. It is also said that hence its natural characteristics which is rubber, the latex
tends to glue itself more strongly to the aggregates and providing strong HMA mixtures.
This suggests that adding polymer into binder could enhance the performance of the
binder itself.
63

64. Rut Depth
Control
latex
14
12
Depth(MM)
10
8
6
4
2
0
0
401 801 1201 1601 2001 2401 2801 3201 3601 4001 4401 4801 5201 5601 6001 6401
Cycles (60 Cycles Per Minute)
Figure 4.1 Asphalt Pavement Analyzer Graph (control and latex sample) for 19 mm
nominal size
64

65. Rut Depth
Control
Polyacrlate
14
12
Depth(MM)
10
8
6
4
2
0
0
400 800 1200 1629 2029 2429 2829 3229 3629 4029 4429 4829 5229 5629 6029 6429
Cycles (60 Cycles Per Minute)
Figure 4.2 Asphalt Pavement Analyzer Graph (control and polyacrlate sample) for 19 mm
nominal size
65

66. Rut Depth
Control
Latex
14
12
Depth(MM)
10
8
6
4
2
0
0 401 8011201
1601
2001
2401
2801
3201
3601
4001
4401
4801
5201
5601
6001
6401
6801
7201
7601
8001
Cycles (60 Cycles Per Minute)
Figure 4.3 Asphalt Pavement Analyzer Graph (control and latex sample) for 19 mm
nominal size
66

67. Rut Depth
Control
Polyacrylate
14
12
Depth(MM)
10
8
6
4
2
0
0 400 8001200
1629
2029
2429
2829
3229
3629
4029
4429
4829
5229
5629
6029
6429
6829
7229
7629
Cycles (60 Cycles Per Minute)
Figure 4.4 Asphalt Pavement Analyzer Graph (control and polyacrlate sample) for 19 mm
nominal size
67

68. CHAPTER 5
CONCLUSION AND RECOMMENDATION
5.1.
Conclusion
The Superpave method using HMA mixtures performances was used in this study to
evaluate the rutting performance between modified asphalt and unmodified asphalt of
Superpave mixtures. During the preparation of the samples it was noted that the mixes
with the polymer modified binder which are latex and poly were difficult to mix
compared to preparation of control sample. At lower temperature, it will increase the
cooling effects on the mix thus it increases the stiffness of the mix and viscosity of the
asphalt. For polymer modified binder the temperature of the pan and velocity of the blade
must be aware during mixing in order to stabilize the properties of the polymer modified
binder.
The compiled final sample was obtained through the calculation where the weight of
aggregates and asphalt were being adjusted and the preparation sample was based on the
Superpave mix design procedures. The HMA mixtures were tested in Servopac Gyratory
Compactor, and Asphalt Pavement Analyzer and their evaluation of ruting performance
were compared with modified (latex and poly) and unmodified (control) asphalt of HMA
mixtures.
Meeting the current rutting performance requirement appears to result in high rutting
depth for control samples; consequently these mixtures may have poor rutting resistances
even though these samples may meet the standard of the Superpave mix design. It
appears that at lower asphalt contents which the OBC is lower such as 5.3% for latex, the
68

69. aggregate may have greater impact on the mixture performance of rutting, overriding that
of the asphalt. The rut depths were measured and analyze for the sample tested in the
APA seems to have a correlation with rutting resistance of the sample. In this study, it
was determined that average rut depth of control, latex and polyacrylates at 6500 cycles
were 7.5mm, 4.9mm and 6.5mm respectively. It was obtained that latex has the least
depth of rut compared to control and polyacrylate hence it show that latex is highly
recommended as a polymer modified binder to use in road construction in purpose to
against rutting. The sample with high rut depth in the APA corresponds to have a low
rutting resistance of the sample, while a relatively low depth of the rut in the APA also
relates to a relatively higher rutting resistance of the sample.
5.2.
Recommendation
The following recommendations are based on the above findings evolving from this study
and other related research efforts. Further study and more data are required to validate the
findings and conclusions as well as increase the level of confidence in these findings.
i.
The rate of change of weight of aggregates and asphalt content, , measured from
compaction in the Servopac Gyratory Compactor may in terms of density will be
a potential parameter for assessing the rutting resistance of coarse mixtures in the
laboratory and, therefore, should be investigated further for this purpose. It must
also be investigated for fine mixtures.
ii.
Rut depth measured from the APA has a potential relationship with the rutting
resistance of mixtures and could be used to predict the rutting performance of
mixtures in the laboratory.
69

70. iii.
Study can be conducted by using all modified asphalt in three types of gradation
such as 9.5 mm NMAS and 12.5mm NMAS through an engineering test such as
APA to observed the correlation of rutting on different gradation.
iv.
The study also recommended to be done by adding some additive such as
hydrated lime in a small percentage to the different types of hot mix asphalt
gradation. The outcomes of the research are to determine whether the additives
help to resist rutting and identify types of gradation with additives can resist
rutting better.
70

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