THE RELATIONSHIP BETWEEN MARSHALL STABILITY, FLOW AND
RUTTING OF THE NEW MALAYSIAN HOT-MIX ASPHALT MIXTURES
MUKHTAR ELSEDDIG ABUKHETTALA
A project report submitted in partial fulfillment of the
requirements for the award of the degree of
Master of Engineering (Civil - Transportation and Highway)
Faculty of Civil Engineering
Universiti Teknologi Malaysia
NOVEMEBER 2006
iii
“To my beloved father and mother,
my lovely brother and my dearest sisters.
To my brother-in-law (Yousef),
for their eternal love, support and encouragement…”
iv
ACKNOWLEDGEMENT
First and foremost, I would like to express my deep gratitude and most
heartfelt thanks to the Almighty "ALLAH" (SWT) for His Blessing, for lightening up
my heart with the torch of knowledge and for seeing me throughout my lifetime.
With utmost respect and pleasure, I would like to express my sincere thanks
and appreciation to my academic supervisor Dr. Mohd Rosli Bin Hainin, who
continuously guided me throughout every step of my thesis work and generously
shared his time and knowledge with me. I am greatly indebted to him for his
encouragement and incessant help to achieve more than I expected of myself.
My gratitude and deep appreciation go to my co-supervisor, Associate
Professor Dr. Abdul Aziz Bin Chik, for having the patience of a saint whilst I was
conducting my laboratory work and orienting me in the correct research direction.
My special thanks must be extended to technical staff members at the
highway & transportation engineering laboratory at UTM for their collaboration. In
particular, En. Suhaimi, for his steadfast assistance while carrying out my laboratory
work.
I would like to express special great words of thanks to my family, who
tirelessly encouraged and supported me in countless ways to pursue my Master's
Degree. I thank my brother-in-law, Dr.Yousef, for his brotherly love, moral support
and incessantly assist with words of assurance throughout my way. Without their
sacrifices, understanding and endless care, I would not have had the opportunity to
study in Malaysia and I could never have reached where I am today.
Last but not least, Million words of thanks for friends of mine who showed
their concern and support all the way.
vi
ABSTRACT
Hot-mix asphalt (HMA) has reasonably served well in the past. The high tire
pressures and increased wheel loads of traffic moving on roads is primarily
considered as the major cause of increasing the premature rutting of asphalt
pavement. Therefore, it has become necessary to improve HMA mixtures to
withstand the increased stresses. Many road pavement agencies have been using
Marshall Mix Design method for designing HMA mixtures and it is believed that
fundamental changes must be made in the aggregate components of HMA to reduce
rutting to tolerable levels. Properties of Hot-mix asphalt mixtures such as stability,
durability, and resistance to permanent deformation (rutting) can be largely affected
by aggregate gradation. Hence, gradation is considered as the centerpiece property of
aggregate that influences the performance of asphalt pavement. However, other
factors such as field compaction efforts and bitumen content have also some effects
on pavement performance. In Malaysia, rutting has been a continuous problem and it
has become necessary to give more attention to selecting materials that could
minimize this problem. Jabatan Kerja Raya (JKR) has recently set up a new standard
for asphalt mixes that could be rut resistant. In This research, an attempt was made
to evaluate the relationships between Marshall Stability, flow and rut depth of the
New Malaysian Hot-Mix Asphalt mixtures using five different asphalt mixtures,
which are ACW10, ACW14, ACB28, SMA14 and SMA20. Stability and flow values
of all mixes had been determined at the optimum bitumen content obtained from
Marshall Design Method. Rut depth has been evaluated using the Three-Wheel
immersion tracking Machine. Results have revealed that there is no good correlation
between Stability and flow of the new Malaysian HMA mixtures. It was concluded
that Stability, Flow and Stiffness can not be used to predict Rutting potential of the
New Malaysia hot-mix asphalt mixtures.
vi
ABSTRAKT
Campuran panas berasfalt (HMA) telah terbukti untuk berfungsi dengan baik.
Tekanan tayar yang tinggi dan peningkatan pembebanan lalulintas dikatakan sebagai
sebab utama untuk meningkatkan aluran permatang pada turapan berasfalt. Olen itu,
ianya menjadi keperluan untuk memperbaik campuran HMA untuk menangung
peninkatan tekanan. Banyak agensi jalan yang mengunakan kaedah rekabentuk
campuran Marshall dalam mereka bentukkan campuran HMA dan dipercayai
perubahan besar mestilah dibuat terhadap komponen agregat HMA untuk
mangurangkan aluran ke tahap yang bolah diterima.Siafat-sifat campuran panas
berasfalt seperti kestabilan, ketahanlasakan, dan rintangan terhadap ubahbentuk
kekal
(akuran)
bole
dipegaruhi
oleh gradasi
agregat.dengan
itu
gradasi
dipertimbangkan sebagai sifat utama agregat yang mempengaruhi pelaksanaan
turapan
berasfalt.
Walau
bagaimanapun,
faktor-faktor
lain
seperti
usaha
permandaptdan kandungan bitumen juga mempunyai kesan terhadap perlaksanaan
turapan. Di Malaysia, aluran yang sememangnya telah menjadi masalah harualah
diberi perhatian yang lebih dalam pemilihan bahan untuk mengurangkan masalah ini.
Baru-baru ini, Jabatan Kerja Raya (JKR) telah megemukakan piawaian yangbaru
untuk campuran-campuran asfalt yang boleh merintangi aluran. Dalam kajian ini,
satu percubaan telah dilakukan untuk menilai hubungan diantara kestabilan Marshall,
aliran, dan kedalaman aluran campuran berasfalt panas Malaysia yang baru dengan
mengunakan lime campuran berasfalt yang berbeza, iaitu ACW10, ACW14,
CAW28, SMA14, dan SMA20. nilai-nilai kestabilan dan aliran untuk kesemua
campuran telah ditentukan pada kandungan bitumen optimum yang diperoleh
daripada kaedah rekabentuk Marshall. Kedalaman aluran telah dinilai dengan
menggunakan mesin jejak tiga roda. Keputusan menunjukkan bahawa tiada korelasi
yang baik diantara kestabilan dan aliran bagio campuran HMA Malaysia yang baru.
Boleh disimpulkan bahawa kestabilan, aliran, dan kekukuhan tidak boleh digunakan
untuk meramalkan potensi aluran bagi campuran panas berasfalt Malaysia yang baru.
vii
TABLE OF CONTENTS
CHAPTER
I
II
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAKT
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
x
LIST OF FIGURES
xii
LIST OF APPENDIXES
xiv
INTRODUCTION
1.1
Aggregate Gradation
1
1.2
Permanent Deformation Resistance
2
1.3
1.4
Problem Statement
Objective
4
1.5
Scope of the Study
4
4
LITERATURE REVIEW
2.1
General Introduction
2.2
Description Of rutting Distress Mechanism
6
7
2.3
Rutting Severity Levels
8
2.4
Rutting Evaluation Tests
2.4.1 Hamburg Wheel Tracking Machine
11
11
2.4.2
Asphalt Pavement Analyzer
14
2.4.3
Three-Wheel Immersion Tracking Machine
16
viii
III
METHODOLOGY
3.1
Introduction
17
3.2
Laboratory Tests Procedure
21
3.3
Aggregate Preparation (Sieve Analysis Of Coarse
And Fine Aggregate (ASTM C136-84A
3.4
Determination Of Aggregate Specific Gravity
3.4.1
Determination Of Coarse Aggregate
Specific Gravity
3.4.2
Determination Of fine Aggregate Specific
Gravity
3.5
23
26
26
27
Marshall Mix Design (ASTM D1559)
29
3.5.1
Mix Design Preparation
30
3.5.2
Theoretical Maximum Specific Gravity And
Density of Bituminous Paving Mixtures
3.5.3
33
Bulk Specific Gravity Of Compacted
Bituminous Mixtures Using Saturated
36
Surface-Dry Specimens (ASTM D2726)
3.5.4
Resistance To Plastic Flow of Bituminous
Mixtures Using Marshall Apparatus (ASTM
39
D1559)
3.5.5
Volumetric properties of compacted
mixtures
3.6
Evaluating of Rutting Potential Using the ThreeWheel Immersion Tracking Machine
3.6.1
Determination of Number of Roller Passes
3.6.2
Procedure of the Three-Wheel Immersion
Tracking tests
IV
43
45
46
48
3.7
Specification
49
3.8
Data analysis
49
RESEARCH RESULTS AND ANALYSIS
4.1
Introduction
51
4.2
Aggregate gradation
51
ix
4.3
4.4
Sieve analysis
57
4.3.1
Dry sieve analysis
57
4.3.2
Washed sieve analysis
57
Bulk specific gravity of aggregate
57
4.4.1
Bulk specific gravity of coarse aggregate
58
4.4.2
Bulk specific gravity of fine aggregate
58
4.4.3
Mineral filler specific gravity
59
4.4.4
Bulk specific gravity of total aggregate
( S.G blend)
4.5
Specific gravity of Bitumen
60
4.6
Maximum specific gravity of paving mixtures
60
4.7
Effective specific gravity of aggregate
61
4.8
Volumetric properties analysis
62
4.8.1
Voids in total mix (VTM)
62
4.8.2
Voids in mineral aggregate (VMA)
63
4.8.3
Voids filled with bitumen (VFB)
64
4.9
The optimum bitumen content
4.10
Marshall Mix Design results of different mixtures at
the optimum bitumen content
4.11
Evaluation of Rut depth using the Three-Wheel
immersion tracking machine
4.11.1
Determination of number of roller passes
4.11.2
Conduction the Three-Wheel immersion
tracking test
4.12
V
59
Discussion
CONCLUSION AND ECOMMENDATION
64
65
66
66
68
72
74
REFERENCES
75-77
APPENDIXES A - C
78-107
x
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Possible rutting causes and probable treatments
9
3.1
Gradation Limit for Asphaltic Concrete (ACW10)
18
3.2
Gradation Limit for Asphaltic Concrete (ACW14)
18
3.3
Gradation Limit for Asphaltic Concrete (ACB28)
19
3.4
Gradation Limit of combined aggregate (SMA14,
SMA20)
3.5
Design Bitumen Content
3.6
Test and Analyses Parameter for Asphaltic Concrete
(JKR/SPJ/rev2005)
3.7
Minimum sample size requirement for coarse
aggregate specific gravity
3.8
Minimum sample size requirement for Theoretical
Maximum Density (ASTM D2041)
19
20
20
26
34
3.9
Stability Correlation Ratios
42
3.10
SMA Mix requirements (JKR/SPJ/rev2005)
45
3.11
The suggested form of the obtained results
50
4.1.1
Aggregate gradation for ACW10
52
4.1.2
Aggregate gradation for ACW14
53
4.1.3
Aggregate gradation for ACB28
54
4.1.4
Aggregate gradation for SMA14
55
4.1.5
Aggregate gradation for SMA20
56
4.2
Bulk specific gravity of coarse aggregate for different
mixtures
4.3
Bulk specific gravity of fine aggregate for different
mixtures
58
59
xi
4.4
Bulk specific gravity of Blend for different mixtures
59
4.5
Theoretical Maximum density of all used mixtures
60
4.6
Theoretical Maximum density at each asphalt
Content for each asphaltic mixture
4.7
Effective Specific Gravity of each mixture used in this
research
61
62
4.8
Percentage of VTM for different mixtures
62
4.9
Percentage of VMA for different mixtures
63
4.10
Percentage of VFB for different mixtures
4.11
The Optimum Bitumen Content of asphaltic mixes
64
64
4.12
Marshall Mix design results for different mixtures
65
4.13
Results of determining required number of roller
passes
4.14
Results of the Three-Wheel immersion tracking
machine
4.15
Stability, Flow, Stiffness and Rut depth of various
asphaltic mixtures
67
68
69
xii
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Rutting severity levels as classified by JKR
8
2.2
Types of Asphalt pavement rutting
Asphalt pavement rutting due to plastic movement
of the asphalt mix Under heavy loads.
Hamburg Wheel Rut Tester in operation.
Asphalt samples submerged in water prepared for
the HWRT wet test.
Asphalt cylindrical samples after application Of
20,000 Wheel passes (HWRT)
Typical Hamburg Wheel Tracker Test Results
Testing of cylindrical and beam hot-mix asphalt
samples in the APA.
Laboratory Test Flow chart
Sieves from 75μm to 37.5mm are placed on the
mechanical shaker
Washing of Aggregate before sieving process
9
2.3
2.4
2.5
2.6
2.7
2.8
3.1
3.2
3.3
10
12
12
12
13
14
22
24
25
25
3.8
Weighing Aggregate during a Sieve Analysis
Aggregates sieved and separated according
to particle size
Determination of fine aggregate specific gravity
The specimens that have been prepared by Marshall
Mix Design
The ASTM D 2041 test apparatus
3.9
Steps of Bulk Specific Gravity Test
38
3.10
Compression Testing Machine
39
3.11
Speicemen are being immersion in water bath
40
3.12
Lubricating of the guide and its rods prior to testing
40
3.13
Breaking head is placed on a sample
41
3.14
Sample is placed in Marshall stability machine
41
3.4
3.5
3.6
3.7
25
29
32
33
xiii
3.15
Decanting of the sample into the mould
46
3.16
Sample after compacting ready to be tested
47
3.17
The Three-Wheel immersion Tracking Machine
49
4.1 (a)
Gradation limits and mix design curve for ACW10
52
4.1 (b)
Gradation limits and mix design curve for ACW14
53
4.1 (c)
Gradation limits and mix design curve for ACB28
54
4.1 (d)
Gradation limits and mix design curve for SMA14
55
4.1 (e)
Gradation limits and mix design curve for SMA20
56
4.2
Number of roller passes versus %VTM
68
4.3
Roller Passes versus Rut Depth results
69
4.4 (a)
Stability versus Rut Depth
70
4.4 (b)
Flow versus Rut Depth
70
4.4 (c)
Flow versus Stability
71
4.4 (d)
Stiffness versus Rut Depth
71
xiv
LIST OF APPENDIXES
APPENDIX
A
TITLE
PAGE
1.
Aggregate gradation
79-81
2.
Dry & washed-sieve analysis results
82-91
3.
Percentage of bitumen contents & Required weight
of asphalt for different mixtures
92
B
Bulk Specific Gravity of coarse and fine Aggregates
94-98
C
Maximum Specific Gravity of Loose Mixtures
99-101
D
Marshall Mix Design results
102-107
CHAPTER I
INTRODUCTION
1.1
Aggregate gradation
Aggregate gradation is the distribution of particle sizes expressed as a
percentage of the total weight. The gradation as a percent of the total volume is of
most importance, but expressing gradation as a percent by weight is much easier and
is a standard practice. Gradation is determined by sieve analysis, sieves are stacked
from the largest openings on the top to the smallest opening on the bottom, and a pan
is placed at the bottom of the stack, by passing the material through a series of sieves
and weighing the material retained on each sieve, gradation can be determined. The
gradation of an aggregate is normally expressed as total percent passing various sieve
sizes [1].
Some properties of Hot-mix asphalt mixture such as stiffness, stability,
durability, fatigue resistance and resistance to permanent deformation, can be largely
affected by aggregate gradation. Therefore, gradation is considered the most
important property of aggregate that influences the performance of asphalt
pavements [1].
Stability of HMA is important aspect that affects the performance in the field.
It can be increased by increasing the internal friction between aggregates and
improving the shear resistance. Increasing of mix stability through increase antiparticle contact and reduce voids in the mineral aggregate may result from gradation
2
that provide a maximum density. However, there must be sufficient air void spaces
to permit enough asphalt cement to be incorporated to ensure durability, while still
leaving some air space in the mixture to avoid bleeding and rutting [1].
Improper and unsuitable aggregate gradation causes a lot of trouble to the
performance of HMA. One of the problems caused by poor aggregates gradation is
tender mixes, which rut easily under traffic load and cannot be compacted in the
normal manner because of their slow ability to develop sufficient stability to
withstand the weight of the compaction equipment [1].
In recent years, there has been an increase in the use of large stone mixes to
minimize rutting potential of HMA. Using of large stone mixes increases the volume
concentration of the aggregate and contributes to a reduction of both asphalt content
and cost of the mix. However, the use of a maximum aggregate size greater than
(1inch) often results in a harsh mixes that tend to segregate during construction [1].
In addition, using of the Stone Mastic Asphalt (SMA) has been widely used
in recent years due to it is excellent rutting resistance on high volume roads. The
high resistance to rutting is due to high proportion of coarse aggregate in SMA
mixtures, which represents about 70-80% of the mix and produces stone-to-stone
contact. SMA mixture has an ability to improve stability and increase durability at
the same time. The stability in SMA is obtained through internal friction in the selfsupporting stone skeleton.
1.2
Permanent deformation resistance
Resistance to permanent deformation is one objective should be kept in mind
when designing HMA. The mix should not distort (rut) or displace when subjected
to traffic load. The resistance to permanent deformation (rutting) becomes critical
during hot weather months when the viscosity of the asphalt binder is low and the
traffic load is primary carried by the mineral aggregate structure. Resistance to
permanent deformation is controlled by selecting the quality aggregate with proper
3
gradation and selection the asphalt content that is enough but not too much to
provide adequate air voids exist in the mix [1].
The mix proportions for a properly compacted asphalt concrete paving
mixtures are determined in the laboratory during mix design testing. The ability of a
properly proportioned asphalt paving mix to resist potentially damaged effects of the
asphalt binder stripping from the aggregate particles is also routinely evaluated in the
laboratory. To perform properly in the field, a well-designed asphalt paving mixture
must be placed within the proper temperature range and must be adequately
compacted. HMA mixtures should be evaluated for the following properties [5]:
•
Stability: which is the load that a well-compacted paving mixture can accept
and withstand before failure. Sufficient mix stability is required to satisfy the
demands of traffic without rutting or bleeding problems [5].
•
Flow: which is the maximum deformation measured at the instance of failure
under the load applied. The ratio of Marshall Stability to flow approximates
the mix's load deformation characteristics and therefore indicates the material
resistance to permanent deformation [5].
The asphalt concrete mix design process is conducted to determine an
aggregate gradation that meets the requirements of the specifications in terms of
voids in mineral aggregate(VMA), air voids content (voids in total mix VTM) and
density. Any changes that occur in the gradation can alter the properties of the mix.
The degree of change in the mix properties is the function of the change in gradation
of the aggregate. If that change is significant, the potential for an increase in the
permanent deformation of the mix can also be significant [2].
4
1.3
Problem statement
The high increase in number of vehicles and heavy traffic volumes on the
roads at an alarming proportion consequently increases the tire pressures and
produces heavier axle loads imposed on pavement structure.
Hence, there has
become a need to enhance asphalt pavement mixtures that may prone to rutting, to
withstand the increase of loading, mitigate adverse affects on pavement performance
and reduce occurrence of premature rutting. Gradation is a property that needs a
careful consideration due to its effect on performance of HMA mixtures. In addition,
mix properties, such as air voids, stability and resistance to permanent deformation
are strongly affected by the proper gradation of aggregates.
1.4
Objective
The objective of study is:
•
Evaluating the relationships between Marshall Stability, flow and rutting
potential of the New Malaysian HMA mixtures.
1.5
Scope of the Study
The scope of this study concentrates on preparing asphalt concrete mixes
based on the new Malaysian hot-mix design mixtures using Marshall Mix design
method. The optimum bitumen content of all mixes will be obtained and the stability
and flow values at the obtained OBC will be determined. In addition, rutting
potential (rut depth) of different mixtures will be evaluated by means of the ThreeWheel immersion-tracking machine.
Asphaltic concrete mixtures that will be used in this research include; Asphalt
concrete for wearing coarse (ACW10 and ACW14), Asphalt concrete for binder
5
coarse ACB28, and Stone Mastic Asphalt (SMA14 and SMA20) in accordance with
the new aggregate gradation proposed by JKR.
Samples will be compacted with two different levels of compaction, which
are; 75 blows / face for asphaltic concrete for wearing and binder course mixtures
and 50 blows / face for Stone Mastic Asphalt mixtures.
CHAPTER II
LITRATURE REVIEW
2.1
General Introduction
Marshall Stability is generally a measure of mass viscosity of the aggregateasphalt cement mixture. It is significantly affected by the angle of internal friction of
aggregate and the viscosity of asphalt cement at 60°C (140°F). This stability is
defined as the maximum load (that the specimen can withstand) carried by a
compacted specimen tested at 60°C (140°F) at a loading rate of 2 inches/minute
(50.8mm/minute).
The main purpose of Marshall Stability test is to measure the strength of an
asphalt mixture that has been compacted to a standard laboratory compactive effort.
One of the easiest ways to increase the stability of an aggregate mixture is by
changing to higher viscosity grade of asphalt cement [1]. Anything that increases the
viscosity of the asphalt cement increases the Marshall stability. The stability of a
mixture in the field is affected by some parameters, such as the ambient temperature,
aggregate gradation, type of loading, rate of loading, tire contact pressure and
numerous mixture properties. The primary use of Marshall Stability is in evaluating
the change in stability with increasing asphalt content to aid in selection the optimum
asphalt content [1].
The flow is equal to the vertical deformation of the sample (measured from
the start of loading to the point at which stability begins to decrease). It is measured
7
at the same time as Marshall Stability. High flow values indicate a plastic mix that
will experience deformation under traffic, whereas low flow values indicate a mix
with percent of air voids higher than the normal voids and insufficient asphalt [1].
The flow value or flow index is the total vertical deformation of the specimen
at the maximum load. Marshall Stiffness which is Marshall Stability divided by flow
is a term sometimes used to characterize asphalt mixture. A higher value of stability
divided by flow indicates a stiffer mixture and hence, indicates the mixture is likely
more resistance to permanent deformation.
2.2
Description of rutting distress mechanism
Rutting of asphalt concrete pavement is the permanent deformation of any of
the layers in the structural system. It is considered as one of the most common and
destructive pavement distresses. There are five areas of distress that affect
performance of Hot-Mix asphalt which are: fatigue cracking, rutting, thermal
cracking, friction, and moisture susceptibility. All of these distresses can result in
loss of performance but rutting is the one distress that is most likely to be a sudden
failure as a result of unsatisfactory hot mix asphalt. Other distresses are typically
long-term failures that show up after a few years of traffic.
The rutting distress is recognized as a surface depression in the wheel path.
Ruts are particularly evident after a rain when wheel paths are filled with water.
When rutting path filled with water, it can cause vehicle hydroplaning, which is
considered hazardous because ruts tend to pull a vehicle towards the rut path as it is
steered across the rut path.
8
2.3
Rutting severity levels
Rutting severity has been classified according to JKR specification into three
different levels, which are low, moderate and high level. The following is a brief
explanation of the three different levels respectively.
•
Low severity level: Where rut depths of less than 12mm (measured under
1.2 m straight edge) [4].
•
Moderate severity level: Where rut depths of between 12mm and 25mm
(may include slight longitudinal cracks) [4].
•
High severity level: Rut depths of greater than 25mm (may include
multiple longitudinal or crocodile cracks) [4].
a) Low severity: Rut depth <12mm
b) Moderate severity: Rut depth
between12 mm to 25 mm
c) High severity: Rut depth >25mm
Figure 2.1: Rutting severity levels as classified by JKR
9
In addition, JKR has identified some possible causes and probable treatments
of rutting .The following table illustrates some of them.
Table 2.1: Possible rutting causes and probable treatments
No.
Possible Causes
Probable Treatments
1.
Inadequate pavement thickness.
Strengthen overlay or reconstruction
2.
Inadequate compaction of layers
Reconstruction.
3.
Unstable bituminous mixes.
Use stiffer mix.
4.
Overstressed sub grade, which
Reconstruction.
deforms permanently.
5.
Excess bitumen in the mix.
Proper selection of asphalt content for
the mix for the purpose
Asphalt pavement rutting can be caused by insufficient pavement structural
support allowing excessive stress to be transferred to the sub grade (structural
rutting); however, the most common type of rutting is asphalt ‘stability’ rutting
caused by the plastic movement of asphalt mix under heavy, often slow moving
loading. The deformation is exaggerated during periods of high ambient temperature.
An increase in the stiffness of asphalt concrete mixture at a given temperature causes
an increase in the rutting resistance of the pavement. To the extent that asphalt
influences mix stiffness, an increase of the viscosity of the asphalt cement at the
same temperature can produce a mix with improved rutting resistance.
Over densification
Plastic flow
Figure 2.2: Types of Asphalt pavement rutting (19)
10
Figure 2.3: Asphalt pavement rutting due to plastic movement of the asphalt
mix Under heavy loads. (18)
Rutting in pavement usually develops gradually with increasing numbers of
load applications. It typically appears as longitudinal depressions in the wheel paths
sometimes accompanied by small upheavals to the sides. It is generally caused by a
combination of densification (decrease in volume and, hence, increase in density)
and shear deformation and can occur in any one or more of the HMA layers as well
as in the unbound materials underneath the HMA. Eisenmann and Hilmer (6) also
found that rutting is mainly caused by deformation flow rather than volume change.
Predicting performance of HMA is very difficult due to the complexity of
HMA, the complexity of the underlying unbound layers and varying environmental
conditions. Presently, there are no specific methods being used nationally to design
and control HMA to control rutting.
The cost of asphalt pavement rutting repairs can be very high and disruptive
on traffic operations. A reliable, accelerated laboratory performance test to evaluate
rutting resistance of asphalt mixes is considered necessary. Several laboratory
methods are in use for test for rutting characteristics of asphalt concrete mixture.
11
2.4
Rutting Evaluation Tests
Test that have the potential for predicting rutting resistance include uniaxial
static and repeated load tests, triaxial static and repeated load tests, and simulative
tests. The simulative tests primarily include wheel-tracking tests. The Asphalt
Pavement Analyzer (APA), Hamburg Wheel Rut Tester (HWRT) and French
Laboratory Rutting Tester (FLRT) are considered to provide reasonable results and
good correlation with field performance. These rut testers have been used in Canada
and the United States for mix designs, pavement evaluation, assessment of new
materials, quality control, and pavement failure investigation [8].
2.4.1
Hamburg Wheel-Tracking Machine
The HWTD, It is used to evaluate rutting and stripping. Tests within the
HWTD are conducted on a slab that is 260 mm wide, 320 mm long, and typically 40
mm thick (10.2 in x 12.6 in x 1.6 in). These slabs are normally compacted to 7±1
percent air voids.
Testing in the HWTD is conducted under water at temperatures ranging from
25°C to 70°C (77°F to 158°F), with 50°C (122°F) being the most common used
temperature. Loading of samples in the HWTD is accomplished by applying a 705-N
(158-lb) force onto a 47-mm-wide steel wheel (or 50-mm-wide rubber wheel). The
steel wheel is then tracked back and forth over the slab sample. Two samples can be
tested simultaneously in one HWRT run. Some researchers in Europe consider that
the use of the steel wheel is too severe and may cause excessive damage to asphalt
samples. There is more experience with wheel tracking tests than with any other type
of test to predict rutting. Other tests have promise but more work is needed to
finalize details before they are utilized for mix control (research is underway to do
this) [13].
Test samples are loaded for 20,000 passes or until 20 mm of deformation
occur. The travel speed of the wheel is approximately 340 mm per second. Colorado
12
DOT recommends maximum allowable rut depth (figure 2.6) of 4.0 mm at 10,000
wheel passes and 10 mm at 20,000 wheel passes while the Texas DOT specification
requires that the rut depth be less than 12.0 mm at 20,000 passes [9].
Figure 2.4: Hamburg Wheel Rut Tester in operation.
Figure 2.5: Asphalt samples submerged in water prepared for the
HWRT wet test.
Figure2.6: Asphalt cylindrical samples after Application of 20,000
Wheel passes (HWRT).
13
As shown in Figure 2.7, results obtained from the HWTD consist of rut
depth, creep slope, stripping inflection point, and stripping slope. The creep slope is
the inverse of the deformation rate within the linear region of the deformation curve
after post compaction and prior to stripping (if stripping occurs). The stripping slope
is the inverse of the deformation rate within the linear region of the deformation
curve, after the onset of stripping. The stripping inflection point is the number of
wheel passes corresponding to the intersection of the creep slope and the stripping
slope. This value is used to estimate the relative resistance of the HMA sample to
moisture induced damage [10].
Figure 2.7: Typical Hamburg Wheel Tracker Test Results (10)
Numerous studies have been conducted to compare results of Loaded Wheel
Tester (LWT) to the actual field performance. A joint study by the FHWA and
Virginia Transportation Research Council evaluated the ability of three LWTs to
predict rutting performance. The relationship between LWT and field rutting for all
three LWTs was strong. The HWTD had the highest correlation (R²=0.91), followed
by the APA (R²=0.90) and FRT (R²=0.83). From that study, it was concluded that
results obtained from the wheel tracking devices seem to correlate reasonably well to
actual field performance when the in-service loading and environmental conditions
of that location are considered [11].
14
2.4.2
Asphalt Pavement Analyzer
The Asphalt Pavement Analyzer (APA), shown in Figure 8 below, was
developed in 1995. The APA has been used to evaluate the rutting, fatigue, and
moisture resistance of HMA mixtures. It features controllable wheel load and contact
pressure adjustable temperature inside the test chamber. In evaluating rutting
potential using the APA, a wheel is loaded onto a pressurized linear hose and tracked
back and forth over a testing sample to induce rutting. Most tests are typically carried
out to 8,000 cycles (one cycle is defined as the backward and forward movement of
the wheel over samples) and samples can be tested while submerged in water.
Figure 2.8: Testing of cylindrical and beam hot-mix asphalt samples in the APA.
Testing specimens for the APA can be either beam or cylindrical. Beams are
most often compacted to 7 % air voids, while cylindrical samples have been
fabricated to both 4 % and 7 % air voids. Beams or cylindrical samples are placed in
a test chamber. The amount of permanent deformation (rut depth) under repetitive
load is monitored by a computer and display in a screen. Test temperatures for the
APA have ranged from 40.6°C to 64°C (105°F to 147°F). The most recent work has
15
been conducted at or slightly above expected high pavement temperatures. Wheel
load and hose pressure are 445 N and 690 kPa (100 lb and 100 psi), respectively.
Rut depth is measured with an electronic dial indicator. Some States in the
USA use a maximum deformation of 5.0 mm in the APA as the pass-fail criterion for
mixes designed to be used on interstate highways [7].
After the APA came on the market, the Florida Department of Transportation
conducted a study using three mixes of known field performance. The three mixes of
were tested in the APA. Within this study, beams and cylinders were both tested.
Results showed that both sample types ranked the mixes similar to the field
performance data. Therefore, the study has concluded that the APA had the
capability to rank mixes according to their rutting potential [12].
Aggregate gradation is an important factor that influences the permanent
deformation potential of HMA. One common way to characterizing aggregate
gradation is by making a gradation plot on a 0.45 power chart, which also contains a
maximum density line. It is believed that gradation passing through the restricted
zone can have low stability. Experience shows that stiff binder courses with bigger
aggregates have less rutting potential compared to relatively more flexible wearing
courses with fine aggregate and higher binder content. Statistical analyses of APA rut
depth obtained from tested mixes with different aggregate gradation indicates a
significant difference between rut depths of mixes gradation passing above, through
and below the Superpave restricted zone [14].
A study was conducted to evaluate affects of aggregate gradation on
performance of asphalt mixture in university of Kansas in 1999. Two mixes were
used in the study, one of coarse gradation and the other of fine gradation. The two
mixes were evaluated for air-void, permanent deformation and gradation. Then they
were coarsened to simulate the effects of production variability and segregation and
test repeated. Coarsening of mixtures led to an increase in VTM, VMA that
decreases the stability of mixture. Fine mixture had less rutting (5mm) than the
coarse mixture (8.9m) using APA. Results from this study was indicated that fine
16
aggregate was stronger that coarse aggregate as measured by APA to evaluate rutting
potential [15].
Another study was carried out to evaluate rutting potential of pavement mixes
using 4-in and 6-in samples. From this study, it was concluded that the amount of
voids in total mix VTM is likely the most important property of asphalt mixtures that
relates to rutting and plastic flow of the asphalt mixtures is likely to begin once the
VTM are reduced to approximately 3%.
The study draw a conclusion that there is a good possibility that the voids
level decreases under compaction to some point at which rutting begins to occur and
at which time the voids level begins to increase due to shoving of the mixture. In
addition, mixes having flow values above 10 tended to have higher amount of
rutting. Coring of 4-in and 6-in samples from the site indicated that most observed
rutting occurred in layers, which contained fine aggregate gradation and high asphalt
content [16].
2.4.3
Three-Wheel Immersion Tracking Machine
The wheel tracking tests have been largely used for evaluating of rutting
behavior. The Transport and Road Research Laboratory of the United Kingdom
adopted the Three Wheels Immersion Tracking Machine in 1951. The main purpose
of this machine is to evaluate pavement-rutting resistance using moving wheels that
simulate the actual moving loads of traffic.
CHAPTER III
METHODOLOGY
3.1
Introduction
The main aim of this project is to evaluate the relationships between Marshall
Stability, flow and rutting potential of the new Malaysian Hot-Mix Asphalt mixtures.
Rutting potential will be evaluated using the Three-Wheels immersion Tracking
Machine which is available in the highway and transportation laboratory at Universiti
Teknologi Malaysia.
Samples will be prepared and tested according to the JKR/SPJ/rev2005 as a
guide to attain that the laboratory works and materials fulfill the Malaysian Road
works circumstances. Five different asphaltic mixtures will be used throughout the
laboratory work namely; Asphalt concrete for wearing course ACW10 and ACW14,
Asphalt concrete for binder course ACB28 and Stone Mastic Asphalt (SMA14 and
SMA20). Tables 3.1, 3.2, 3.3 and 3.4 below show the appropriate envelopes for the
new aggregate gradations that have been introduced recently by JKR, which will be
used in this project.
All samples will be prepared based on Marshall Laboratory compaction
method and by using of 100mm mould size. For each laboratory design mix
gradation, three specimens will be prepared for each bitumen content within the
range given in Table 3.5 below at increments of 0.5 percent in accordance with
ASTM D1559 using 75-blows/face compaction standard (heavy traffic) for (ACW10,
ACW14, ACB28) mixtures, and 50-blows/face for (SAM14, SMA20) mixtures.
18
Once Specimens have been compacted using Marshall Hammer, they will be tested
for stability and flow.
Table 3.1: Gradation Limit for Asphaltic Concrete (ACW10)
Mix Type
Wearing Course
B.S Sieve Size,mm
% Passing By Weight
28.0
-
20.0
-
14.0
100
10.0
90-100
5.0
58-72
3.35
48-64
1.18
22-40
0.425
12-26
0.150
6-14
0.075
4-8
PAN
-
Table 3.2: Gradation Limit for Asphaltic Concrete (ACW14)
Mix Type
Wearing Course
B.S Sieve Size,mm
% Passing By Weight
28.0
-
20.0
100
14.0
90-100
10.0
76-86
5.0
50-62
3.35
40-54
1.18
18-34
0.425
12-24
0.150
6-14
0.075
4-8
PAN
-
19
Table 3.3: Gradation Limit for Asphaltic Concrete (ACB28)
Mix Type
Binder Course
B.S Sieve Size,mm
% Passing By Weight
28.0
100
20.0
72-90
14.0
58-76
10.0
48-64
5.0
30-46
3.35
24-40
1.18
14-28
0.425
8-20
0.150
4-10
0.075
3-7
PAN
-
Table 3.4: Gradation Limit of combined aggregate (SMA14, SMA20)
ASTM Sieves
Percentage by weight Passing Sieve
Sieve Size, mm
SMA14
SMA20
19
100
100
12.5
100
85-95
9.5
72-83
65-75
4.75
25-38
20-28
2.36
16-24
16-24
0.600
12-16
12-16
0.300
12-15
12-15
0.075
8-10
8-10
PAN
-
-
After obtaining the optimum bitumen content, two samples will be prepared
for verification and identifying stability and flow values using the optimum bitumen
content .Thereafter, two beams will also be prepared using the same bitumen
content to carry out rutting potential test using the Three-Wheel immersion tracking
machine.
20
The design bitumen contents for the design process of all mixtures will be as
stated in JKR's specifications that are in the in the appropriate range given in Table
3.5.
Table 3.5: Design Bitumen Content
ACW10 - Wearing coarse
5.0-7.0%
ACW14 - Wearing coarse
4.0-6.0%
ACB28 - Binder coarse
3.5-5.5%
SMA14, SMA20 – Stone Mastic Asphalt
5.0-7.0%
In addition, results obtained from the laboratory work will be compared with
JKR/SPJ/rev2005 requirements as given in Table 3.6 below.
Table 3.6: Test and Analyses Parameter for Asphaltic Concrete (JKR/SPJ/rev2005)
Parameter
Wearing Course
Stability
S
>8000N
Flow
F
2.0-4.0mm
Stiffness
S/F
>2000N/mm
Air voids in mix VTM
3.0-5.0%
Voids in aggregates filled with bitumen VFB
70-80%
Bituminous binder of asphaltic concrete for wearing and binder coarse
(ACW10, ACW14 and ACB28) shall be a bitumen of penetration grade 80-100,
which conforms to MS 124 .Whereas the bituminous binder to be used with Stone
Mastic Asphalt (SMA14 and SMA20) shall be of performance grade PG76 or higher
in compliance with AASHTO Standard M320-02.
21
3.2
Laboratory Test Procedure
The laboratory tests are divided into several stages begin with the aggregates
preparation. The gradation of aggregates is used to design the Marshall mixes
samples. Firstly, sieve analysis will be carried out to separate aggregate into different
sizes. Then specific gravity for coarse and fine aggregate will be determined.
Washed-sieve analysis will be done to determine the percentage of dust and silt-clay
material in order to check the need for the filler material. Thereafter, Marshall Test is
conducted to determine the optimum bitumen content (OBC) for each mix type. The
value of the OBC is important for designing the mixes to indicate other mix
performance tests. The value of the OBC will be used to prepare two samples and
two beams to determine the stability and flow of Marshall Test and to evaluate the
rutting potential using the OBC. Figure 3.1 below shows the laboratory test flow.
22
Dry sieve analysis to divide aggregate into
different sizes
Washed sieve analysis to determine
percentage of dust & silt-clay material
Aggregate blending to obtain the desired
gradation
Determination of specific gravity for
coarse & fine aggregates
Preparing of mixtures (ACW10, ACW14,
ACW28, SMA14, SMA20)
Obtaining of the Maximum Theoretical
Specific Gravity
Determination of bulk specific gravity of
Marshall compacted mixtures
Resistance to Plastic Flow of the Marshall
compacted Mixtures
Volumetric properties analysis
Evaluating of rutting depth using the
Wheel Track machine.
Results and analysis
Figure 3.1: Laboratory Test Flow chart
23
3.3
Aggregate preparation (Sieve analysis of Coarse and Fine Aggregate
ASTM C136-84A)
This method is used to determine the aggregate gradation which is proposed
for the project. The results are then used to determine the compliance of the particles
size distribution with the applicable specification requirements and to provide
necessary data to control the production of various aggregate sizes and mixture
containing aggregates. Standard procedure for a dry-sieve analysis is given in ASTM
C136 and for a washed-sieve analysis for determine the amount of material passing
the No 200 (0.075mm) sieve the procedure is given in ASTM C117.The dry method
is faster and is often used to estimate the actual gradation .
The materials which will be used for this study such as aggregates must be
dried an overnight in an oven for at least one day. This procedure is to ensure the
moisture and impurities in aggregate have been removed. Then some portion of
aggregate will be taken as a sample to determine the specific gravity.
The remaining aggregates will be separated into single sizes using sieving
machine. Aggregate retained on each sieve then collected and stored in large
containers or bins. The container will be marked with the sieve size to avoid any
confusing between the aggregate sizes.
A)
Scope:
The test is performed to determine the particles size distribution of coarse and
fine aggregates.
B)
Apparatuses:
i.
Balances;
ii.
Sieves;
iii.
Mechanical sieve shaker;
iv.
Oven.
24
C)
Procedure:
i.
Aggregates to be used in the blend must be dried to a constant
weight in an oven at a temperature of 110±5°C;
ii.
Suitable sieve sizes are selected and nested in order of decreasing
size of opening from the top to the bottom;
iii.
Sample is then placed on the top the sieves .Shaking process using
Mechanical Sieve Shaker is then started and continued to agitate
the stacked sieves for a sufficient period of time (normally for
about 3 minutes);
iv.
Sieving process is continued until there is no residue on an
individual sieve will pass the sieve using a continues hand sieving;
Figure 3.2: Sieves from 75μm to 37.5mm
are placed on the mechanical shaker
v.
The quantity of the material on a given sieve is limited so that all
particles have an opportunity to reach the sieve opening during
the sieving operation;
25
Figure 3.3: Washing of Aggregate before sieving process
Figure 3.4: Weighing Aggregate during a Sieve Analysis
Figure 3.5: Aggregates sieved and separated According to particle size.
26
3.4
Determination of aggregate specific gravity
The specific gravity of an aggregate is useful in making weight-volume
conversions and in calculating voids content in a compacted HMA samples. Specific
gravity for both types of aggregate (coarse and fine) will be determined.
3.4.1
A)
B)
Determination of coarse aggregate specific gravity
Apparatuses:
i.
Balance, which should be accurate to 0.5g of the sample weight;
ii.
Sample container;
iii.
Water tank;
iv.
4.75mm sieve size.
Procedure:
i.
Weigh the aggregate and wash it to clean it from the dust;
ii.
The minimum weight of tested sample should be as shown below:
Table 3.7: Minimum sample size requirement for coarse aggregate specific gravity
test
Nominal Maximum Aggregate Size
Weight of sample
12.5 mm
2.0 kg
19.0 mm
3.0 kg
25.0 mm
4.0 kg
37.5 mm
5.0 kg
27
iii.
Soak aggregates in water for 24 hours;
iv.
After 24 hours, aggregates are placed into a basket in water path
and its weight is recorded while submerging in water for 3
minutes. This mass is recorded as A;
v.
Dry the aggregate with a damp towel until it is saturated surface
dry and weigh it again. The mass of a saturated dry surface is
recorded as B;
vi.
Dry the sample in an oven for 24 hours at 110±5°C;
vii.
Cool the sample at a room temperature and weigh it again. This
mass will be the mass of oven dry aggregate and is recorded as C;
viii.
The bulk specific gravity of coarse aggregate can be calculated by
using the following equation:
Bulk specific gravity =
Weight of oven dry aggregates C
Weight of SSD in air B – Weight in water A
3.4.2
A)
Determination of fine aggregate specific gravity
Apparatuses:
i.
Balance, which should have a capacity of 1 kg and accuracy of
0.1g ;
ii.
Pycnometer;
iii.
Mould in the form of a frustum of a cone with the following
dimension: 40 ± 3mm inside diameter at the top, 90 ± 3mm inside
diameter at the bottom and 75 ± 3mm in height;
iv.
Tamper weighing 340 ± 15kg and have a flat circular face 25 ±
3mm in diameter.
28
C)
Procedure:
i.
Fine aggregate sample is prepared and 6% water is added to the
total weight of the sample. Sample is permitted to stand for about
24 hours before conducting the test;
ii.
Then, a pycnometer is cleaned and weighed empty;
iii.
The ¾ filled pycnometer is weighed and its mass is recorded as B;
iv.
Afterwards, aggregates are mixed with water until aggregates are
stuck together. Then cone test is carried out. If about 1/3 of
aggregate slumps after 25 light drops of tamper about 10mm
above the top surface of fine aggregate in the cone, then the
aggregates are saturated dry surface;
v.
Pour the water away until the pycnometer is left to about ¼ filled;
vi.
About 500 g fine aggregate is added to the ¼ filled pycnometer
This weight is recorded as the weight of saturated surface dry
aggregate and it is designated as S;
vii.
The pycnometer is filled with water until the original level of ¾ of
its volume (to the calibration mark) and its weight filled with
sample and water is recorded as C;
viii.
Shake the pycnometer well for nearly 20 minutes to get rid of air
in the sample;
ix.
Dry the sample in an oven until the aggregate achieve a constant
weight. Weigh the oven dry aggregate and record it as A;
29
Figure 3.6: Determination of fine aggregate specific gravity.
x.
The specific gravity of fine aggregate can be determined from the
following formula:
Bulk specific gravity =
A
B+S-C
where:
3.5
A:
weight of oven dry aggregate in air, gm;
B:
weight of pycnometer filled with water, gm;
C:
weight of pycnometer with water and aggregate, gm;
S:
weight of saturated surface dry aggregate, gm.
Marshall Mix Design ( ASTM D1559)
The main purpose of the design process is to determine the optimum bitumen
content (OBC) of each asphaltic mixture. For the laboratory tests, all the mixes will
be compacted using two different levels of compaction, which are 75 blows/face for
Asphaltic Concrete mixtures and 50 blows/face for Stone Mastic Asphalt mixtures.
After obtaining the OBC, two samples from each mixture will be prepared using the
obtained OBC and tested for verification to get the realistic volume properties.
The aggregates blend that will be used for mixtures preparation must fall
within the specification requirements. Properties such as density and bulk specific
30
gravity of aggregate and bitumen used for each mixture must be determined earlier
before carrying out Marshall Test.
3.5.1
Mix design preparation
A) The apparatuses that will be used for mix design preparation are:
B)
i.
Specimen Mold Assembly;
ii.
Compaction Hammer;
iii.
Compaction Pedestal;
iv.
Specimen Mold Holder;
v.
Breaking Head
vi.
Oven;
vii.
Mixing Apparatus;
viii.
Thermometer;
ix.
Mixing Tools.
Test specimens are:
i.
Aggregates mix designation that have been dried at a temperature
of 1050C to 1100C;
ii.
C)
Heated asphalt cement.
Mixtures Preparation:
i.
Aggregates are weighed according to the amount of each size
fraction that required for each mix design;
ii.
The pan is heated on a hot plate to a temperature of 280C;
31
iii.
Charge the pan with the heated aggregates and dry mix
thoroughly;
iv.
Preheated bituminous materials that required to the mixture are
weighted;
v.
Prevention of losing the mix during the mixing process must be
taken with subsequent handling. The temperature shall not to be
more than the limits;
vi.
Afterwards, aggregates and bitumen are rapidly mixed until
thoroughly until all aggregate are well-coated;
vii.
Finally, mixture is removed from the pan and is left a side to be
ready for the compaction process.
D)
Compaction of specimens:
The procedure begins with recording the mixture temperature and observing
it until it reaches the desirable compaction temperature. The process will follow the
procedure listed below:
i.
The mold assembly and the face of compaction hammer are clean
and heated in a boiling water ,a hot plat or an oven at a
temperature of 930C to 1500C;
ii.
Filter paper that is cut into pieces fit the mould’s diameter and
placed at the bottom of the mold before placing the mixtures;
iii.
The mixture that has been prepared is then placed in the mold, and
stirred by the spatula or trowel for 15 times around the perimeter
and 10 times over the interior;
32
iv.
The collar is removed and the surface will be smoothed with the
trowel to slightly rounded shape;
v.
Next, the compaction temperature is recorded once again,
vi.
The collar then will be assembled to the compaction pedestal in
the mold holder;
vii.
The 75 blows of compaction hammer is applied with a free fall
distance of 500mm from the mold base, and the compaction
hammer is assured to be perpendicular to the base of the mold
assembly;
viii.
After compaction, the base plate is removed and the same blows
are compacted to the bottom of the sample that has been turned
around;
ix.
After that, the collar is lifted from the specimen carefully,
x.
Next, transfer the specimen to smooth surface at a room
temperature for an over-night;
xi.
Lastly, record the weight and examine the sample.
Figure 3.7: The specimens that have been prepared by Marshall Mix Design
33
3.5.2
Theoretical Maximum Specific Gravity and Density of Bituminous
Paving Mixtures (ASTM D 2041-91)
A)
Scope:
The method covers the determination of the density and theoretical
maximum specific gravity of loose (uncompacted) HMA specimens at 25°C. Test
results are used to compute air voids and density in the compacted mix.
B)
Apparatuses:
i.
Vacuum container (bowl);
ii.
Balance;
iii.
Vacuum pump, capable of evacuating air from the vacuum
container to a residual pressure of 30 mm of HG;
iv.
Manometer or vacuum gauge;
v.
Thermometer; and
vi.
Water path.
Figure 3.8: The ASTM D 2041 test apparatus
34
C)
Procedure:
i.
Size of the sample shall conform to the requirements shown in
table 3.8. Samples larger than the capacity of the container may be
tested a portion at a time.
Table 3.8: Minimum sample size requirement for Theoretical Maximum Density
(ASTM D2041)
Nominal Maximum Aggregate Size
Minimum Mass of sample
37.50 mm
4000 gm
25.00 mm
2500 gm
19.0 mm
2000 gm
12.50 mm
1500 gm
9.50 mm
1000 gm
4.75 mm
500 gm
i.
Samples are prepared using the same procedure of preparing
Marshall samples but without using any compactive effort;
ii.
Particles of the paving mixture sample are separated by hand, so
fine aggregate particles are not larger than 6.3mm (¼in);
iii.
Weight of the vacuum container in air is determined before
placing sample and recorded as A;
iv.
Also, vacuum container is weighed in water and recorded as B;
v.
The sample is cooled to the room temperature, placed into vacuum
container, weighed and recorded as C;
vi.
The net mass of sample is recorded as D;
35
vii.
Sufficient water is then added to the sample in the vacuum
container and should cover at least 1 inch (2.54 cm) over the
sample;
viii.
Air trapped in the sample is removed by increasing the vacuum
gradually until the pressure manometer reads 25mm of HG. This
pressure is maintained for 10 minutes;
ix.
During the vacuum period, the container and sample are agitated
continuously by mechanical device;
x.
After about 10 minutes, the vacuum is gently released. The
container and sample are then placed in water and weighed. Their
weight is recorded as E;
xi.
T.M.D values for different samples must be within ± 0.018 of one
another;
xii.
T.M.D value is used to calculate Effective Specific Gravity
(S.Geff) of the aggregate. The calculated (S.Geff) value is used to
determine T.M.D values at binder contents other than the binder
content chosen for mixing T.M.D samples.
1.
Calculation:
The theoretical maximum specific gravity (Gmm) can be calculated from the
flowing equation:
Gmm = D / (D+B-E)
where:
D:
Weight of sample in air (gm) and can be calculated as
following:
D = C-A (Weight of container & sample in air – weight of
container in air).
36
B:
Weight of the bowl in water, gm and
E:
Weight of the bowl and sample in water, gm.
The effective specific gravity of aggregate blend used can be determined
using the following formula:
T.M.D = 100 / [(% aggregate / S.G eff) + (% bitumen / S.G bitumen)
3.5.3
Bulk Specific Gravity of Compacted Bituminous Mixtures Using
Saturated Surface-Dry Specimens (ASTM D 2726)
This test covers the determination of bulk specific gravity of the samples.
This method can be only used for a specimen that does not absorb more than 2% of
water by volume. Result from the test is used to calculate the density (unit weight)
and percentage of air voids of compacted mixes. Water displacement method is used
to determine the bulk specific gravity where specimen will be weighed in three
conditions (in air, when submerged in water and saturated dry surface condition).
A)
B)
Apparatus that used in this test are listed below:
ii.
Balance; and
iii.
Water bath.
Procedure:
i.
First, the specimen is dried to constant mass;
ii.
Specimen is cooled to a room temperature at 25±50C and the dry
mass is recorded as A;
iii.
Each specimen is immersed in a water path at 250C for 3 to 5
minutes and the immersed mass is then recorded as C;
37
iv.
Remove specimen from the water by blotting the surface with a
damp towel and determine the surface-dry mass which designated
as B;
v.
The bulk specific gravity can be calculated by using the following
equation;
Bulk specific gravity =
Viii
A
B-C
Bluk specific gravity of Samples at the same binder content must
be within an average of ± 0.020 of one another.
a)
b)
The specimen is weight to get the dry air mass.
The specimen is immersed to get the mass in water.
38
c) The specimen is wiped with a towel &Weighed to get the surface-dry mass.
Figure 3.9: Steps of Bulk Specific Gravity Test
39
3.5.4
Resistance to Plastic Flow of Bituminous Mixtures Using Marshall
Apparatus (ASTM D1559)
The test covers the measurement of resistance to plastic flow of cylindrical
specimens [101.6mm (4 in) in diameter and 63.5mm (2.5in) high] of asphalt mixture
loaded on the lateral surface by means of Marshall Apparatus. The method is used
for mixtures containing asphalt cement, asphalt cutback and aggregate up to 25.4 mm
maximum size. The purpose of this test is measuring the strength of a compacted
asphaltic mixture to a standard laboratory compactive effort. In addition, the test is
used as apart of Marshall Mix design procedure for selecting design bitumen content.
Figure 3.10: Compression Testing Machine
Marshall testing machine is a compression-testing device, designed to apply
loads to test specimens through semi-circular testing heads at a constant strain rate of
58.5mm/min. (2in/min.). The water path in which the sample is immersed for at least
45minutes, should be at least 150 mm (6in) deep and thermostatically controlled at
60°C±1°C (140°F±1.8°F). The temperature was selected since it is approximately the
maximum pavement temperature in the summer. Thereby, it provides the weakest
condition of HMA mixture.
Flow test is carried out simultaneously with stability test. It is executed by
holding the flow meter over the testing head and reading the meter at the instance the
specimen fails under pressure.
40
The test procedure is listed as below:
i.
Specimens that have been prepared are immersed in the water bath
for 30 to 45 minutes at a maintained temperature of 60 ±10C ;
Figure 3.11: Specimens are being immersing in water bath
ii.
The guide rods and the tests heads are cleaned prior to carrying
out the test. Also, the guide rods shall be lubricated so that the
upper test slides freely over them;
Figure 3.12: Lubricating of the guide and its rods prior to testing
iii.
The testing-head temperature is recommended to be between 210C
to 380C;
41
iv.
Specimen then is removed from the water bath and be placed in
the lower segment of the breaking head;
v.
After that, the upper segment of the breaking head is placed on the
specimen. The complete assembly is then located in its position on
the testing machine;
Figure 3.13: Breaking head is placed on a sample
vi.
The flow meter is placed in position over one of the guide rods;
vii.
Then, adjust the flow meter to zero while holding the sleeve
firmly;
Figure 3.14: Sample is placed in Marshall Stability Machine
42
viii.
The load is applied to the specimen by means of a constant
movement rate of 50.8mm until the maximum load is reached .
Notice that reading must be taken before loading the specimen;
ix.
As the applied load is started to decrease, the dial reading is taken
and recorded as the maximum applied load the sample can sustain
(the stability force);
x.
Record the last reading of the flow meter. This value will be taken
as the flow value in mm unit;
xi.
Testing must be completed within 30 seconds of removing sample
from the hot water bath;
xii.
The applied load must be corrected when thickness of specimen is
other than (2½ in.) or 63.5mm by using the proper multiplying
factor from Table 3.9 below;
Table 3.9: Stability Correlation Ratios
Volume of specimen
Approximate thickness
(cm³)
of Specimen.(mm)
444 to 456
55.6
1.25
457 to 470
57.2
1.19
471 to 482
58.7
1.14
483 to 495
60.3
1.09
496 to 508
61.9
1.04
509 to 522
63.5
1.00
523 to 535
65.1
0.96
536 to 546
66.7
0.93
547 to 559
68.3
0.89
560 to 573
69.9
0.86
574 to 585
71.4
0.83
586 to 598
73.0
0.81
Correlation Ratio
43
3.5.5
Volumetric properties of compacted mixtures
The total volume of small pockets of air between the coated aggregate
particles in a compacted paving mixture, expressed as a percentage of the bulk
volume of the compacted paving mixture is defined as the total volume of voids in
mixture (VTM).Voids in total mix can be calculated using this formula :
VTM = [1 - (Gmb / Gmm)] x 100
Or
VTM = (VA / VT) x 100
where:
VTM :
Air voids in a compacted mixture.
Gmb
:
Bulk specific gravity of a compacted mixture.
Gmm
:
Maximum specific gravity (T.M.D).
VA
:
Volume of air voids.
VT
:
Total volume of compacted specimen.
The voids in the mineral aggregate VMA are defined as the intergranular void
spaces between aggregate particles in a compacted paving mixture that include the
air voids and the effective asphalt content (volume of asphalt not absorbed into the
aggregates), expressed as a percentage of the total volume of the compacted paving
mixture. In other words, VMA is the total volume of voids within the mass of the
compacted aggregate. The VMA can be determined by using the following equation:
VMA = (100 - Pb) Gmb / S.Geff
where:
VMA :
Voids in mineral aggregate.
Pb
Percentage of asphalt content by total weight of mixture.
:
S.Geff :
Effective specific gravity of aggregates.
Voids filled with asphalt VFA, is defined as the percent of the volume of
VMA that is filled with asphalt cement.VFA can be calculated using the following
formula:
44
VFA = [(VMA – VTM) / VMA] x 100
where:
VFA
:
Voids filled with asphalt.
VMA :
Voids in mineral aggregate.
VTM :
Air voids in a compacted mixture.
From density and voids analysis, and results from stability and flow test,
results will be plotted as following:
i.
Bulk density versus asphalt content.
ii.
Stability versus asphalt content.
iii.
Flow versus asphalt content.
iv.
% voids in the total mix VTM versus asphalt content.
v.
% voids in the aggregate filled with asphalt VFA versus asphalt
content.
For asphaltic concrete mixtures (ACW10, ACW14, and ACB28), the
optimum asphalt content will be determined as described by the National Asphalt
Paving Association (NAPA), which is the percentage of asphalt corresponds to 4%
air voids from VTM curve.
For Stone Mastic Asphalt mixtures (SMA14 and SMA20), the optimum
asphalt content shall be determined by averaging four values of the asphalt content
determined as follows:
i.
Peak of curve taken from the stability graph.
ii.
Flow equals to 3 mm from the flow graph.
45
iii.
Peak of curve taken from the bulk specific gravity graph.
iv.
VTM equals to 3.5% from the VTM graph.
The individual tests values (Stability, Flow, VMA and VTM) for stone mastic
asphalt mixtures at the mean optimum bitumen content shall be read from the plotted
smooth curves and comply with the design parameters given in table 3.10 below.
Table 3.10: SMA Mix requirements (JKR/SPJ/rev2005)
Parameter
3.6
Wearing Course
Stability
S
min. 6200N
Flow
F
2.0-4.0mm
Air voids in mix VTM
3.0-4.0%
Voids in mineral aggregate VMA
Min. 17%
Evaluation of Rutting Potential using the Three-Wheel immersion
Tracking Machine
After obtaining the optimum bitumen content, two beams from each mixture
type will be prepared and tested to evaluate rutting potential of each specific mixture.
Beams are of dimension (407mm × 90 mm × 443 mm) and will be tested using the
Three-Wheel immersion Tracking Machine shown in figure 3.17.
The main function of this machine is to evaluate the rutting resistance of
pavement samples loaded by means of moving wheels that simulate the actual
moving loads on the field.
46
3.6.1
Determination of number of roller Passes
A simple trial and error method is usually carried out to determine the
appropriate number of roller passes for a compaction purpose. The numbers of roller
passes have been initially suggested are 20, 30, 40, 80, 100, 150 and 200 passes. The
test procedure is listed as below:
i.
First, aggregates are mixed together according to the gradation for
each asphaltic mixture design;
ii.
The obtained optimum bitumen content from Marshall test is
added to each mixture accordingly;
iii.
After mixing aggregate thoroughly with the optimum bitumen
content, it is decanted into the mould and compacted using
different numbers of roller passes;
Figure 3.15: Decanting of the sample into the mould
iv.
The initial number of roller passes are suggested to be 20, 30, 40,
80, 100, 150 and 200 respectively;
v.
After compacting, beams are left to cool at a room temperature;
47
Figure 3.16: Sample after compacting ready to be tested
vi.
Once beams have been cooled, they are extruded from the mould
and Bulk Specific Gravity test of Compacted Bituminous
Mixtures Using Saturated Surface-Dry Specimens (ASTM D
2726) is conducted;
vii.
Voids in total mix is then calculated for all mixtures and plotted
against the number of passes;
viii.
Rolling shall be continued as long as it is necessary to achieve the
appropriate requirement stated in JKR aspect;
ix.
Compaction is carried out in order to achieve particular densities
of different mixtures. In this research, for all mixtures, the number
of roller passes is selected to be of which produces a percentage of
air voids of about 7%. The 7% air voids is considered as the
typical in-situ percent of air voids after construction a pavement;
x.
Voids in total mix is calculated using the following formulas :
T.M.D = 100 / [(% aggregate / S.G eff) + (% bitumen / S.G bitumen)]
Mass of sample in Air
Bulk specific gravity =
Mass of SSD sample – Mass in water
VTM = [1 - (Gmb / Gmm)] x 100
48
3.6.2
Procedure of the Three-Wheel Immersion Tracking Machine Test
Three specimens can be tested simultaneously using three moulds. The
moulds are of dimension 407mm × 90 mm × 443 mm. Once samples have been
compacted, the Three-wheel immersion-tracking test is carried out. The procedure of
conduction the test is as listed below:
i.
First, the well-compacted samples are placed into the oven for
approximately 3-5 hrs at a temperature of 60°C;
ii.
Temperature of the water path in the wheel-tracking machine is
maintained at 60°C;
iii.
Before conducting the test, samples are placed in the tracking
machine and immersed in water path for 30 minutes;
iv.
The wheel is tracked back and forth with a travel speed about 40
passes/min;
v.
One cycle is defined as the backward and forward movement of
the wheel over samples;
vi.
Rutting depth is recorded after 500, 1000, 2000 and 5000 passes
respectively;
vii.
The reading will be taken at three different placed of each beam to
obtain the average rut depth value;
49
Figure 3.17: The Wheels Immersion Tracking Machine
3.7
Specification
All samples will be prepared according to the JKR/SPJ/rev2005 as a
guideline. The above-mentioned Tables (3.1, 3.2, 3.3, 3.4 and 3.5) show the
appropriate envelopes of combined aggregates gradation and the range of the design
bitumen content that will be used in this study. The optimum bitumen content will be
determined based on NAPA method. The obtained results from the analysis process
will be compared to the JKR/SPJ/rev2005 requirements specifications of all types of
mixtures as given in Tables 3.5 and 3.7.
3.8
Data analysis
The outcome results from the laboratory work will be analyzed and presented
in such a way that reflects the objective of the research. Results will be recorded and
presented as shown in Table 3.11 below.
50
Table 3.11: The suggested form of the obtained results
Parameter
Mixture
Stability (N)
Flow (mm)
Stiffness
Rut depth
(N/mm)
(mm)
ACW10
ACW14
ACB28
SMA14
SMA20
Lastly, results will be presented and plotted on four different graphs, which
are flow versus rut depth, stability versus rut depth, flow versus stability and stiffness
versus rut depth. This aims to evaluate the relationships between the four main
parameters that are related to pavement performance.
CHAPTER IV
RESEARCH RESULTS AND ANALYSIS
4.1
Introduction
The analysis process of all data obtained by the laboratory work will be
discussed in depth in this chapter. Several tests have been conducted to determine
stability, flow and rut depth values of five different HMA mixtures, which are
(ACW10, ACW14, ACB28, SMA14 and SMA20). These results were obtained
based on the optimum bitumen content that had been determined from Marshall Mix
design method. Tests that were carried out include: dry and washed sieve analysis,
specific gravity for coarse and fine Aggregate test, Marshall Mix design to obtain the
optimum bitumen content, stability and flow test and evaluation of rut depth using
the Three-Wheel immersion tracking machine.
4.2
Aggregate gradation
Aggregate gradation is considered as the centerpiece component of HMA
mixture design. A proper selection of aggregate gradation plays a very significant
role in providing a dense, durable and stable mixture and it is affected almost all
HMA mixture properties.
52
Aggregate gradation was selected according to JKR/SPJ/2005 by choosing
the best curve for each HMA mixture. The best design curves chosen and then
plotted on the power of 0.45 graphs. Based on the design curve, the weight of
retained aggregate on each sieve was determined. Gradation limits and mix design
curve for all five mixtures are shown in figures 4.1(a) to (e).
% Passing
ACW10 Aggregate Gradation
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Lower Limit
Upper Limit
Mix Design Curve
MDL
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
2.5
2.75
3
3.25
3.5
Sieve Size ^0.45
Figure 4.1 (a) Gradation limits and mix design curve for ACW10
Table 4.1.1: Aggregate gradation for ACW10
Sieve
Size
mm
14
10
5.0
3.35
1.18
0.425
0.150
0.075
Filler
Size^0.45
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
-
Specification
Limits (%)
Lower
Upper
100
100
90
100
58
72
48
64
22
40
12
26
6
14
4
8
-
Percent
Passing
Cumulative
retained
Percent
retained
100
95
65
56
27
15
10
6
-
0
5
35
44
73
85
90
94
100
0
5
30
9
29
12
5
4
6
∑=100 %
53
% Passing
ACW14 Aggregate Gradation
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Lower Limit
Upper Limit
Mix Design Curve
MDL
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25
Sieve Sixe ^0.45
Figure 4.1(b): Gradation limits and mix design curve for ACW14
Table 4.1.2: Aggregate gradation for ACW14
Sieve
Size
mm
20
14
10
5.0
3.35
1.18
0.425
0.150
0.075
Filler
Size^0.45
3.850
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
-
Specification
Limits (%)
Lower
Upper
100
100
90
100
76
86
56
62
40
54
18
34
12
24
6
14
4
8
-
Percent
Passing
Cumulative
retained
Percent
retained
100
93
79
56
47
23
14
10
6
-
0
7
21
44
53
77
86
90
94
100
0
7
14
23
9
24
9
4
4
6
∑=100 %
54
%Passing
ACB28 Aggregate Gradation
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
0.00
Lower Limit
Upper Limit
Mix Design
MDL
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
5.50
Sieve Size ^0.45
Figure 4.1(c): Gradation limits and mix design curve for ACB28
Table 4.1.3: Aggregate gradation for ACB28
Sieve
Size
mm
37.5
28
20
14
10
5.0
3.35
1.18
0.425
0.150
0.075
Filler
Size^0.45
5.109
4.479
3.850
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
-
Specification
Limits (%)
Lower
Upper
100
100
90
100
90
72
76
58
64
48
46
30
40
24
28
14
20
8
10
4
7
3
-
Percent
Passing
Cumulative
retained
Percent
retained
100
95
85
70
56
36
28
17
10
5
4
-
15
30
44
64
72
83
90
95
96
100
0
5
10
15
14
20
8
11
7
5
1
4
∑=100%
55
% Passing
SMA14 Aggregate Gradation
110
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50
Lower Limit
Upper Limit
Mix Design
MDL
Sieve Size ^0.45
Figure 4.1(d): Gradation limits and mix design curve for SMA14
Table 4.1.4: Aggregate gradation for SMA14
Sieve
Size
mm
25
19
12.5
9.5
4.75
2.36
0.600
0.300
0.075
filler
Size^0.45
4.256
4.479
3.850
3.279
2.818
2.063
1.723
1.077
0.680
-
Specification
Limits (%)
Lower
Upper
100
100
100
100
100
100
72
83
25
38
16
24
12
16
12
15
8
10
-
Percent
Passing
Cumulative
retained
Percent
retained
100
100
100
77.5
31.5
20
14
13.5
9
-
0
0
0
22.5
68.5
80
86
86.5
91
100
0
0
0
22.5
46
11.5
6
0.5
4.5
9
∑=100%
56
% Passing
SMA20 Aggregate Gradation
105
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50
Lower Limit
Upper Limit
Mix Design Curve
MDL
Sieve Size ^0.45
Figure 4.1(e): Gradation limits and mix design curve for SMA20
Table 4.1.5: Aggregate gradation for SMA20
Sieve
Size
mm
25
19
12.5
9.5
4.75
2.36
0.600
0.300
0.075
PAN
Size^0.45
4.256
4.479
3.850
3.279
2.818
2.063
1.723
1.077
0.680
-
Specification
Limits (%)
Lower
Upper
100
100
100
100
85
95
65
75
20
28
16
24
12
16
12
15
8
10
-
Percent
Passing
Cumulative
retained
Percent
retained
100
100
90
70
24
20
14
13.5
9
-
0
0
10
30
76
80
86
86.5
91
100
0
0
10
20
46
4
6
0.5
4.5
9
∑=100%
57
4.3
Sieve Analysis
4.3.1
Dry-Sieve Analysis
Sieve analysis was conducted as the first step in Marshall Design process to
divide aggregates into different sizes and obtain the desired aggregate gradation
required for each mixture design. The aggregate gradations for different mixtures
were used in this project are shown in appendix A.
4.3.2
Washed-Sieve Analysis
Washed-sieve analysis was conducted after all the aggregates samples had been
prepared. This test was carried out to get the amount of filler (aggregate with size
smaller than 75µm) coated on the courser aggregates to determine the required
amount of fillers need to be added for each mixture type. Appendix A shows the wet
sieve analysis results of all mixtures.
4.4
Bulk Specific Gravity of Aggregate
Bulk specific gravity of coarse and fine aggregates was determined form the
laboratory tests. Aggregates used in this research were provided from two different
sources (quarries). Aggregates for ACW mixtures were supplied from MRP quarry.
Whereas for SMA mixtures, aggregates were supplied from handsun quarry.
Based on the aggregate gradation for mixes design, tests were conducted to
determine the bulk specific gravity for aggregate from different sources. For ACW
mixtures, test was carried out based on ACW10 aggregate gradation. By identifying
the percentage of coarse, fine aggregate and mineral filler, the bulk specific gravity
of blend aggregate was determined. For SMA mixtures, aggregate gradation for
58
SMA14 was used to determine the specific gravity of coarse and fine aggregates.
Steps of calculating the bulk specific gravity are shown in Appendix B
4.4.1
Bulk Specific Gravity of Coarse Aggregates
Samples were prepared for testing for both sources of aggregate. For
asphaltic concrete for wearing and binder coarse, sample of coarse aggregate used to
determine its specific gravity has been prepared based the aggregate gradation for
ACW10. Aggregate size in the range of 20mm to 5mm was considered as coarse
aggregate when preparing sample for specific gravity determination. The obtained
results of coarse aggregate specific gravity of different mixtures are clarified in table
4.2 below.
Table 4.2: Bulk specific gravity of coarse aggregate for different mixtures
Mixture type
Coarse Aggregate Specific
Gravity (S.Gbulk)
4.4.2
ACW10
ACW14
ACB28
2.586
2.586
2.586
SMA14 SMA20
2.611
2.611
Bulk Specific Gravity of Fine Aggregates
Sizes of aggregate that were considered as fines to find its specific gravity
were from 3.35mm and below. This also was based the aggregate gradation for
asphaltic cement for wearing coarse ACW10 and fro Stone Mastic Asphalt SMA 14.
The obtained results of fine aggregate specific gravity of different mixtures are
shown in Table 4.3 below.
59
Table 4.3: Bulk specific gravity of fine aggregate for different mixtures
Mixture type
Fine Aggregate Specific
Gravity(S.Gbulk)
4.4.3
ACW10
2.522
ACW14 ACB28
2.522
2.522
SMA14 SMA20
2.707
2.707
Mineral Filler Specific Gravity
Ordinary Portland Cement (OPC) has been largely used as filler material for
Marshall Mix .Therefore; it was used in this research as well. It serves as a pond
agent in asphaltic mixtures between aggregate and bitumen. According to previous
work has been carried out in Highway & Transportation laboratory at UTM, the
specific gravity of the OPC was 2.980.
4.4.4
Bulk Specific Gravity of Total Aggregate ( S.GBlend )
Based on the percentage of Coarse, Fine aggregate and mineral filler of each
mixture, the bulk specific gravity of aggregate blend for each mix design was
determined. Table 4.4 shows the results were obtained for different mixtures. By
identifying the specific gravity of coarse and fine aggregate and the percentage of
coarse, fines and mineral filler for each mixture, the bulk specific gravity of total
mixture could be determined.
Table 4.4: Bulk specific gravity of Blend for different mixtures
Mixture type
Combined aggregate specific
gravity (S.GBlend)bulk
ACW10
ACW14
ACB28
SMA14
SMA20
2.551
2.557
2.570
2.641
2.634
The specific gravity of blend has been determined by using the following
equation:
60
S.GBlend ( bulk) =
100
(% coarse Agg. / SG coarse) + (% fine Agg. / SG fin e) + (% filler / SG filler)
For example, S.GBlend for ACW 10 has been determined as following:
S.GBlend (ACW10)
4.5
=
100
(35 / 2.586) + (63 / 2.522) + (2 / 2.98)
= 2.551
Specific Gravity of Bitumen
Bitumen of 80/100 PEN (penetration) grade was used in this study for
asphaltic concrete for wearing and binder coarse mixtures. Whereas for Stone Mastic
Asphalt mixture, Bitumen of PG76 performance grade was used. Previous studies
that have been conducted in Transportation and Highway laboratory at UTM
concluded that specific gravity of bitumen was (1.03) for both types.
4.6
Maximum Specific Gravity of Paving Mixtures
Two methods can be used to calculate the maximum specific gravity of loose
asphaltic mixture. The laboratory test (Rice Method) was used in this research. By
doing so, the theoretical maximum density of loose mixture can be calculated
directly. Table 4.5 shows the obtained results from the laboratory test for all mixtures
used in this research.
Table 4.5: Theoretical Maximum density of all used mixtures
Mixture type
Maximum specific gravity
(Gmm) or T.M.D
ACW10
ACW14
ACB28
SMA14
SMA20
2.401
2.411
2.457
2.414
2.416
61
Theoretical maximum densities were used to calculate the effective specific
gravity of aggregate. Then, the maximum specific gravity at any asphalt content was
determined using this formula:
TMD =
100
(% coarse agg. / SGeff. blended) + (% bitumen / SGbitumen)
Table 4 .6 shows the maximum specific gravity at each asphalt content for each
mixtures used in this research.
Table 4.6: Theoretical Maximum density at each asphalt Content for each asphaltic
mixture
Asphalt
4.7
Maximum Specific Gravity (Gmm) T.M.D
Content %
ACW10
ACW14
ACB28
SMA14
SMA20
3.50
-
-
2.481
-
-
4.00
-
-
2.463
-
-
4.50
-
2.446
-
-
5.00
2.435
2.445
2.427
2.428
2.449
2.452
5.50
2.418
2.410
2.411
2.432
2.434
6.00
2.401
2.393
-
2.414
2.416
6.50
2.384
2.376
-
2.397
2.400
7.00
2.367
-
-
2.380
2.383
OBC
2.387
2.435
Effective Specific Gravity of Aggregate
The effective specific gravity of aggregate was calculated based on the
obtained values of the maximum specific gravity of loose mixture. The effective
specific gravity of aggregate is used in analyzing of volumetric properties of paving
mixtures. The effective densities used for analysis process of each mixture are shown
in table 4.7.
62
Table 4.7: Effective Specific Gravity of each mixture used in this research
Mixture type
ACW10
ACW14
ACB28
SMA14
SMA20
2.624
2.614
2.615
2.641
2.644
Combined aggregate
specific gravity
(S.G effective blend)
4.8
Volumetric Properties Analysis
The volumetric properties which includes voids in total mix (VTM), voids
filled with bitumen (VFB) and voids in mineral aggregate (VMA) for all types of
mixtures (ACW10, ACW14, ACB28, SMA14 and SMA 20) were calculated based
on the effective specific gravity of aggregate.
4.8.1
Voids in total mix (VTM)
The voids in total mix were calculated based on the maximum specific
gravity of loose mixes (Gmm) and the bulk specific gravity of compacted mixes
(Gmb). Results were obtained are shown in Table 4.8.
Table 4.8: Percentage of VTM for different mixtures
Asphalt
VTM (%)
Content %
ACW10
ACW14
ACB28
SMA14
SMA20
3.50
-
-
6.9
-
-
4.00
-
-
5.3
-
-
4.50
-
5.0
-
-
5.00
7.7
8.1
5.7
3.5
9.2
7.2
5.50
6.3
5
3.2
8.4
6.1
6.00
5.6
3.9
-
7.0
5.4
6.50
3.3
2.4
-
7.1
4.4
63
4.8.2
7.00
2.8
-
-
5.8
4.2
7.10
-
-
-
-
5.7
7.70
-
-
-
7.1
-
8.20
-
-
-
6.3
-
9.60
-
-
-
2.1
-
Voids in mineral aggregate (VMA)
Table 4.9: Percentage of VMA for different mixtures
Asphalt
VMA (%)
Content %
ACW10
ACW14
ACB28
SMA14
SMA20
3.50
-
-
14.8
-
-
4.00
-
-
14.4
-
-
4.50
-
15.1
-
-
5.00
18.6
17.9
16.8
14.9
20.0
18.0
5.50
18.4
17.2
15.7
20.3
18.0
6.00
18.8
17.3
-
20.1
18.4
6.50
17.9
17.0
-
21.1
18.6
7.00
18.5
-
-
21.0
19.4
7.10
-
-
-
-
20.9
7.70
-
-
-
23.5
-
8.20
-
-
-
23.7
-
9.60
-
-
-
23.0
-
64
4.8.3
Voids Filled with Bitumen (VFB)
Table 4.10: Percentage of VFB for different mixtures
Asphalt
4.9
VFB (%)
Content %
ACW10
ACW14
ACB28
SMA14
SMA20
3.50
-
-
53.2
-
-
4.00
-
-
62.9
-
-
4.50
-
67.2
-
-
5.00
58.5
54.9
66.2
76.2
54.0
61.4
5.50
65.9
71.1
79.4
58.6
67.8
6.00
70.2
77.4
-
65.2
72.5
6.50
81.5
86.0
-
66.7
78.0
7.00
84.7
-
-
72.4
79.8
7.10
-
-
-
-
74.1
7.70
-
-
-
69.8
-
8.20
-
-
-
73.7
-
9.60
-
-
-
91.0
-
The Optimum Bitumen Content
There are various methods to obtain the optimum bitumen content of HMA
mixtures. The Asphalt Institute Method and National Asphalt Pavement Association
(NAPA) method are world well-known methods and have been used widely. In this
research, it was proposed to determine the optimum content according to JKR
requirements but due to difficulties in meeting the requirement of JKR specification
(getting the peak of Stability and Density curves), there has become possible to
follow NAPA method as an available proper option. According to this method, the
optimum asphalt content is selected in corresponding to 4% VTM.
Table 4.11: The Optimum Bitumen Content of asphaltic mixes
Mixture type
ACW10
ACW14
ACB28
Optimum Bitumen Content, %
6.30
5.80
4.80
SMA14 SMA20
8.70
8.00
65
4.10
Marshall mix design results of different mixtures at the optimum
bitumen content
After carrying out Marshall Mix design for all 5 mixtures and obtaining the
optimum asphalt content for each mixture, verification test was performed by
preparing 2 samples from each mix to evaluate volumetric properties, stability and
flow values using the OBC. Results are shown in Table 4.12.
Table 4.12: Marshall Mix design results for different mixtures
Mixture Property
VTM, %
VMA, %
VFB, %
Stability, N
Mixture Type
Test Result
Requirement
ACW10
4.1
3% - 5%
ACW14
3.9
3% - 5%
ACB28
4.1
3% - 7%
SMA14
4.2
3% - 5%
SMA20
4.1
3% - 5%
ACW10
18.2
-
ACW14
16.9
-
ACB28
15
-
SMA14
23
Min. 17%
SMA20
21.9
Min. 17%
ACW10
77.2
70% - 80%
ACW14
77.1
70% - 80%
ACB28
72.7
65% - 75%
SMA14
81.9
-
SMA20
81.6
-
ACW10
12370
Min. 8000 N
ACW14
11970
Min. 8000 N
ACB28
7982
Min. 8000 N
SMA14
10490
Min. 6200 N
SMA20
9530
Min. 6200 N
66
Flow, mm
Stiffness, N/mm
ACW10
4.03
2 - 4 mm
ACW14
3.65
2 - 4 mm
ACB28
7.3
2 - 4 mm
SMA14
11
2 - 4 mm
SMA20
14
2 - 4 mm
ACW10
3096.4
Min 2000 N
ACW14
3230.1
Min 2000 N
ACB28
1099
Min 2000 N
SMA14
953.3
-
SMA20
680.7
-
Results achieved by Marshall Mix design method were acceptable. All values
of Optimum bitumen content were complied with the JKR requirements. Except for
SMA mixtures, where the obtained OBC values were complied with AASHTO
requirements, which specifies that the minimum OBC should be 6%. Verification has
approved that all volumetric properties, stability and flow values were complied with
the requirements of JKR specification
4.11
Evaluation of Rut Depth using the Three-Wheel immersion
Tracking Machine
4.11.1 Determination of Number of Roller Passes
Once the optimum bitumen content of all mixtures had been obtained, two
beams from each mixture batched, mixed and compacted to be tested in the ThreeWheel tracking machine for rutting evaluation.
Identifying the required number of roller passes to achieve the appropriate
requirement of the degree of compaction was the most crucial step before carrying
out the Three-Wheel immersion-tracking machine. ACW14 mixture was selected to
be the representative mixture to identify the required number of roller passes that
produces the required percentage of VTM for each mixture after rolling. Based on
67
JKR aspect, the number of roller passes was selected to be which produces VTM of
about 7% (the typical in-place air voids after construction and opening the road to
traffic).
Numbers of Roller passes that were initially used for the trial and error
method are 20, 30, 40, 80, 100, 150 and 200 passes receptively. Specific gravity of
each beam was determined in order to obtain the percentage of air voids after rolling.
By plotting the relationship of number of roller passes versus percentage of air voids,
the required number of passes was determined. It was concluded that the number of
roller passes required to produce 7% VTM was about 200 roller passes which was
selected to be the same number of roller passes for all mixtures. The process of
carrying out the trial and error method is shown in Appendix C.
Table 4.13: Results of determining required number of roller passes
Number of roller passes
Bulk Specific Gravity
% VTM
20
2.179
9.40
30
2.179
9.38
40
2.183
9.22
80
2.196
8.69
100
2.200
8.51
150
2.218
7.76
200
2.221
7.12
Results from the trial and error method to determine the number of roller
passes required to produce the appropriate requirement of compaction density have
proven that as number of roller passes is increased, density is increased. On the other
hand, as number of roller passes is increased, the percentage of VTM showed the
opposite trend and decreased.
68
Number of Roller Passes vs %VTM
9.70
9.60
9.50
9.40
9.30
9.20
9.10
9.00
8.90
VTM %
8.80
8.70
R2 = 0.88
8.60
8.50
8.40
8.30
8.20
8.10
8.00
7.90
7.80
7.70
7.60
7.50
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95 100 105 110 115 120 125 130 135 140 145 150 155
Number of Roller Passes
Figure 4.2: Number of roller passes versus %VTM
4.11.2 Conducting the Three-Wheel Immersion Tracking Test
Once the required number of roller passes had been identified, two beams of
each mixture were prepared to carry out the rutting evaluation test. The machine is
applicable to test three beams simultaneously. A total number of ten beams were
tested. Results were collected up to the maximum allowable number of rolling which
is 5000 roller passes. Results were obtained from this test are shown in Table 4.14.
Table 4.14: Results of the Three-Wheel immersion-tracking machine
Number of Roller Passes
Average Rut Depth (mm)
ACW10
ACW14
ACB28
SMA14
SMA20
0
0
0
0
0
0
500
7.31
8.89
2.93
6.52
1.99
1000
9.88
10.98
3.59
8.34
2.12
2000
10.59
11.90
4.47
9.23
2.28
5000
15.69
14.81
8.2
14.01
4.06
69
Number of Roller Passes versus Rutting Depth
ACW10
25
R2 = 0.990
22.5
ACB28
R2 = 0.988
20
SMA14
R2 = 0.995
17.5
Rutting Depth (mm)
SMA20
15
ACW14
12.5
Power (SMA20)
10
R2 = 0.999
Power (ACB28)
7.5
Power (SMA14)
5
R2 = 0.995
Power (ACW10)
2.5
Power (ACW14)
0
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
Number of Roller Passes
Figure 4.3: Roller Passes versus Rut Depth results
Finally, stability, flow, stiffness and rut depth values of each mix at the
optimum bitumen content were collected and presented as shown in table 4.15.
Table 4.15: Stability, Flow, Stiffness and Rut depth of various asphaltic mixtures
Mixture
Flow
Stability
Stiffness
Rut Depth
Type
(mm)
(N)
(N/mm)
(mm)
ACW10
4.03
12370
3096.4
15.69
ACW14
3.65
11790
3230.1
14.81
ACB28
7.30
7982
1093.4
8.20
SMA14
11.00
10490
953.6
14.01
SMA20
14.00
9530
680.7
4.06
The obtained relationships between the four parameters that are related to
pavement performance (Stability, Flow, Stiffness and Rut depth) are drawn on
graphs 4.4(a) to (d) as shown below.
70
Stability versus Rutting
18.00
17.00
16.00
15.00
14.00
R u t D e p th (m m )
13.00
12.00
11.00
2
Series1
Poly. (Series1)
R = 0.656
10.00
9.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
7500
8000
8500
9000
9500
10000
10500
11000
11500
12000
12500
Stability (N)
Figure 4.4(a): Stability versus Rut Depth
R u t D e p th (m m )
Flow versus Rutting
16.00
15.50
15.00
14.50
14.00
13.50
13.00
12.50
12.00
11.50
11.00
10.50
10.00
9.50
9.00
8.50
8.00
7.50
7.00
6.50
6.00
5.50
5.00
4.50
4.00
2
Series1
Power (Series1)
R = 0.518
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5 10 10.5 11 11.5 12 12.5 13 13.5 14 14.5
Flow (mm)
Figure 4.4(b): Flow versus Rut Depth
71
Flow versus Stability
12500
12250
12000
11750
11500
11250
11000
S tab ility (N )
10750
10500
10250
R2 = 0.345
Series1
Power (Series1)
10000
9750
9500
9250
9000
8750
8500
8250
8000
7750
7500
3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 14.5
Flow (mm)
Figure 4.4(c): Flow versus Stability
Stiffness versus Rutting
18.5
17.5
16.5
15.5
14.5
13.5
R u t D ep th (m m )
12.5
2
R = 0.490
11.5
Series1
Expon. (Series1)
10.5
9.5
8.5
7.5
6.5
5.5
4.5
3.5
2.5
500
750
1000
1250
1500
1750
2000
2250
2500
2750
3000
Stiffness (N/mm)
Figure 4.4(d): Stiffness versus Rut Depth
3250
3500
72
4.12
DISCUSSION
Results of this research will be discussed in this part and conclusion would be
drawn based on it. The conclusion and recommendations will be presented in the
next chapter.
Results achieved by Marshall Mix design method were acceptable. All values
of Optimum bitumen content were complied with the JKR requirements. Except for
SMA mixtures, where the obtained OBC values were complied with AASHTO
requirements, which specifies that the minimum OBC should be 6%. Verification has
approved that all volumetric properties, stability and flow values were complied with
the requirements of JKR specification.
Results from the trial and error method to determine the number of roller
passes required to produce the appropriate requirement of compaction density have
proven that as number of roller passes is increased, density is increased. On the other
hand, as number of roller passes is increased, the percentage of VTM showed the
opposite trend and decreased.
It was observed that from the Three-Wheel immersion tracking machine test,
the relationships between flow and stability is weak which indicated a poor
correlation with R² value of 0.345. Results show that as flow is increased, stability is
increased which is not acceptable.
As presented in stability versus rut depth graph, the obtained relationship
shows a fair correlation with R² of (0.656). The relationship suggests that as stability
is increased, rut depth is also increased which is not expected. Particularly, as a
material becomes more stable, rutting potential should be decreased. Therefore, it
was concluded that stability can not be used to predict rutting potential of the new
Malaysian HMA mixtures.
By plotting the relationships between flow and rut depth, the trend indicated
that while flow value is increased, rut depth shows an opposite intend and decreased
73
which is unexpected. Normally, as flow is increased, rut depth is increased. Although
the correlation is fair with R² of 0.518 but this again shows that, flow can not predict
rutting potential.
An attempt was made to investigate the relationship between stiffness (which
is the ratio of stability divided by flow value) and rut depth. The obtained
relationship shows a weak (poor) correlation with R² of (0.49) and indicates that
stiffness does not have much reliability. Therefore, the trend a show that as stiffness
is increased, the rut depth is also increased which is against the understanding of
asphalt behavior. It is concluded that stiffness cannot be used as an indicator of
rutting potential. Typically, the stiffer the mix, the less the rut depth or in other
words, the higher the stiffness, the lower the rut depth which does not exist from th
obtained relationship.
CHAPTER V
CONCLUSION AND RECOMMONDATIONS
From this study, it can be concluded that there is no correlation between
stability, flow and rutting potential .Therefore, stability flow and stiffness cannot be
used to predict rutting potential of the new Malaysia HMA mixtures.
To improve the findings it might be helpful for future researches to be carried
out using a modern Wheel tracking
machine (e.g. Hamburg Wheel-Tracking
Machine) and make a comparison of the results with the achieved results by the
Three-Wheel immersion Tracking Machine used in this research.
It should be noted that the results were obtained based on a level of
compaction of 75 blows/face for AC mixtures and 50 blows/face for SMA mixtures.
Using different levels of compaction could be useful to study the correlation between
stability, flow, stiffness and rut depth of various mixes at different levels of
compaction.
75
REFERENCES
1.
Freddy L. Roberts, Prithvi S.Kandhal, E. Ray Brown,Dah-Yinn Lee,Thomas
W. Kennnedy. NAPA research and education foundation. “Hot mix asphalt
materials, mixtures, design and construction”. 2nd edition; 1996.
2
“Asphalt paving technology”. Proceedings association of asphalt paving
technologists. Technical sessions. Volume 58; 1989
3.
Harold N. Atkins, PE. “Highway materials, soils and concrete”. 4th edition;
2004.
4.
“A guide to the visual assessment of flexible pavement surface conditions”.
Jabatan Kerja Malaysia; 1992.
5.
Asphalt Institute, Lexington, Kentucky “Mix Design Methods for Asphalt
Concrete and Other Hot-Mix Types “. Manual Series No.2 (MS-2). 6th
Edition; 1996.
6.
Eisenmann, J., and A. Hilmer. “Influence of Wheel Load and Inflation
Pressure on the Rutting Effect at Asphalt-Pavements-Experiments and
Theoretical Investigations.”. Proceedings, Sixth International Conference on
the Structural Design of Asphalt Pavements, Vol. I, Ann Arbor, 392-403,;
1987.
7.
Van de Loo, P.J “Creep Testing, a Simple Tool to Judge Asphalt Mix
Stability.” Proceeding of the Association of Asphalt Paving Technologists,
Volume 43; 1974.
76
8.
Ray Brown, Prithvi Kandhal and Jingna Zhang “Performance Testing for Hot
Mix Asphalt, Executive Summary”. NCAT Report No. 2001-05A, Nov. 2001.
9.
Texas Department of Transportation TDOT “Manual of Testing Procedures”.
10.
Buchanan, M. S. An Evaluation of Laboratory Wheel-Tracking Devices.
National Asphalt Pavement Association, National Center for Asphalt
Technology; Aug. 1997.
11.
Williams, C. R. and B. D. Prowell. Comparison of Laboratory WheelTracking Test Results to WesTrack Performance. Presented at the 78th
Annual Meeting of the Transportation Research Board, Washington, D.C; Jan
1999.
12.
West, R. C., G. C. Page, K. H. Murphy. Evaluation of the Loaded Wheel
Tester.Research Report FL/DOT/SMO/91-391, Florida Department of
Transportation; Dec.1991.
13.
E.RAY BROWN,PRITHVI S. KANDHAL, JINGNA ZHANG. National
Center for Asphalt Technology “performance testing for Hot-Mix Asphalt”.
14.
PRITHVI S. KANDHAL, Rajib B. Mallick, “Effect of aggregate gradation
on permanent deformation potential of dense graded Hot-Mix Aspahlt”.
15.
Stephen A. Cross, Alex Ad-Osei, and Mohd Rosli Hainin “Effects of
aggregate gradation on performance of asphalt mixtures”; JAN1999.
16.
E.R BROWNand STEPHEN A. CROSS. “A study of in-place rutting of
asphalt pavement”.
17.
HAPI Asphalt Pavement Guide. Hawai'I asphalt paving industry.
77
18.
Ludomir Uzarowski, Michel Paradis, Paul Lum,” accelerated performance
testing of Canadian asphalt mixes using three different wheel rut testers”;
2004.
19.
Myron Thiessen, Ahmed Shalaby, Leonnie Kavanagh “Strength testing of inservice asphalt pavement in Manitoba and correlation to rutting”; 2000.
APPENDIXES
79
APPENDIX A
1)
Aggregate gradation
Table A1.1: Aggregate gradation for ACW10
Sieve
Size
mm
14
10
5.0
3.35
1.18
0.425
0.150
0.075
Filler
Size^0.45
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
-
Specification
Limits (%)
Lower
Upper
100
100
90
100
58
72
48
64
22
40
12
26
6
14
4
8
-
Percent
Passing
Cumulative
retained
Percent
retained
100
95
65
56
27
15
10
6
-
0
5
35
44
73
85
90
94
100
0
5
30
9
29
12
5
4
6
∑=100 %
Table A1.2: Aggregate gradation for ACW14
Sieve
Size
mm
20
14
10
5.0
3.35
1.18
0.425
0.150
0.075
Filler
Size^0.45
3.850
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
-
Specification
Limits (%)
Lower
Upper
100
100
90
100
76
86
56
62
40
54
18
34
12
24
6
14
4
8
-
Percent
Passing
Cumulative
retained
Percent
retained
100
93
79
56
47
23
14
10
6
-
0
7
21
44
53
77
86
90
94
100
0
7
14
23
9
24
9
4
4
6
∑=100 %
80
Table A1.3: Aggregate gradation for ACB28
Sieve
Size
mm
37.5
28
20
14
10
5.0
3.35
1.18
0.425
0.150
0.075
Filler
Size^0.45
5.109
4.479
3.850
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
-
Specification
Limits (%)
Lower
Upper
100
100
90
100
90
72
76
58
64
48
46
30
40
24
28
14
20
8
10
4
7
3
-
Percent
Passing
Cumulative
retained
Percent
retained
100
95
85
70
56
36
28
17
10
5
4
-
15
30
44
64
72
83
90
95
96
100
0
5
10
15
14
20
8
11
7
5
1
4
∑=100%
Table A1.4: Aggregate gradation for SMA14
Sieve
Size
mm
25
19
12.5
9.5
4.75
2.36
0.600
0.300
0.075
filler
Size^0.45
4.256
4.479
3.850
3.279
2.818
2.063
1.723
1.077
0.680
-
Specification
Limits (%)
Lower
Upper
100
100
100
100
100
100
72
83
25
38
16
24
12
16
12
15
8
10
-
Percent
Passing
Cumulative
retained
Percent
retained
100
100
100
77.5
31.5
20
14
13.5
9
-
0
0
0
22.5
68.5
80
86
86.5
91
100
0
0
0
22.5
46
11.5
6
0.5
4.5
9
∑=100%
81
Table A1.5: Aggregate gradation for SMA20
Sieve
Size
mm
25
19
12.5
9.5
4.75
2.36
0.600
0.300
0.075
PAN
Size^0.45
4.256
4.479
3.850
3.279
2.818
2.063
1.723
1.077
0.680
-
Specification
Limits (%)
Lower
Upper
100
100
100
100
85
95
65
75
20
28
16
24
12
16
12
15
8
10
-
Percent
Passing
Cumulative
retained
Percent
retained
100
100
90
70
24
20
14
13.5
9
-
0
0
10
30
76
80
86
86.5
91
100
0
0
10
20
46
4
6
0.5
4.5
9
∑=100%
82
2)
Dry & Washed-Sieve Analysis Results
A)
Dry & Washed-Sieve Analysis Test for ACW10
Dry-Sieve analysis results
Table A2.1: Aggregate gradation & required weight of each aggregate size for
ACW10 mixture
Sieve Size
mm
14
10
5.0
3.35
1.18
0.425
0.150
0.075
PAN
Size^0.45
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
-
Percent
Passing
100 %
95 %
65 %
56 %
27 %
15 %
10 %
6%
-
Percent
retained
0%
5%
30 %
9%
29 %
12 %
5%
4%
6%
∑ =100 %
Weight required
(gm)
0
60
360
108
348
144
60
48
72
∑ = 1200
Cumulative
Weight
0
60
420
528
876
1020
1080
1128
1200
Washed-Sieve analysis results
Table A2.2: Washed-sieve analysis result
Sample No.
Weight of sample before washing, A (g)
Weight of oven dry sample in air (after washing), B (g)
Amount of Dust coated on aggregate = A - B
1
2
1128.0
1128.0
1079.3
1076.0
48.70
52.00
Average = 50.35gm
83
Percentage of required filler material for ACW10
Percentage of dust (Filler) = 6% (2% OPC + 4%filler).
2 % OPC (Ordinary Portland Cement) = 0.02×1200 = 24gm.
4 % filler = 0.04×1200 = 48gm.
Amount of dust cotaed on the aggregate ≈ 50gm.
Since the required dust is almost the same amount of dust coated on the aggregate,
only the percentage of OPC (24gm) has been added to total weight of aggregate.
Table A2.3: Final Aggregate gradation used to prepare Marshall samples For
ACW10 after determining amount of dust content coated oaggregates
Sieve
Size
mm
14
0%
Cumulative
Weight of
agg.
0
10
5%
60
60
60
60
60
60
5.0
30 %
420
360
360
360
360
360
3.35
9%
528
108
108
108
108
108
1.18
29 %
876
348
348
348
348
348
0.425
12 %
1020
144
144
144
144
144
0.150
5%
1080
60
60
60
60
60
0.075
4%
1128
48
48
48
48
48
OPC
Added
Dust
Weight of
bitumen
Total
Weight
of sample
2%
1152
24
24
24
24
24
0%
0
0
0
0
0
0
-
-
60.63
67.04
73.53
80.08
86.70
-
-
1212.63
1219.04
1225.53
1232.08
1232.7
%
retained
@
5.0 %
@
5.5 %
@
6.0 %
@
6.5 %
@
7.0 %
0
0
0
0
0
84
B)
Dry & Washed-Sieve Analysis Test for ACW14
Dry-Sieve analysis results
Table A3.1: Aggregate gradation & required weight of each aggregate size for
ACW14 mixture
Sieve Size
mm
20
14
10
5
3.35
1.18
0.425
0.15
0.075
PAN
Size^0.45
3.850
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
0
Percent
Passing
100 %
93 %
79 %
56 %
47 %
23 %
14 %
10 %
6%
0%
Percent
retained
0%
7%
14 %
23 %
9%
24 %
9%
4%
4%
6%
∑ =100 %
Weight required
(gm)
0
84
168
276
108
288
108
48
48
72
∑ = 1200
Cumulative
Weight
0
84
252
528
636
924
1032
1080
1128
1200
Washed-Sieve analysis results
Table A3.2: Washed-sieve analysis result
Sample No.
Weight of sample before washing, A (g)
Weight of oven dry sample in air(after washing), B (g)
Amount of Dust coated on aggregate = A - B
1
2
1128.0
1128.0
1084.3
1086.1
43.70
41.90
Average =42.80gm
85
Percentage of required filler material for ACW14
Percentage of dust (Filler) = 6% (2% OPC + 4%filler).
2 % OPC (Ordinary Portland Cement) = 0.02×1200 = 24gm.
4 % filler = 0.04×1200 = 48gm.
Amount of dust coated on the aggregate ≈ 42.80gm.
Then, 48 - 42.80 = 5.2gm. filler that must be added to the total weight of aggregate.
Table A3.3: Final Aggregate gradation used to prepare Marshall samples for
ACW14 after determining amount dust content coated an the aggregate
Sieve
Size
mm
14
0%
Cumulative
Weight of
agg.
0
10
5%
60
60
60
60
60
60
5.0
30 %
420
360
360
360
360
360
3.35
9%
528
108
108
108
108
108
1.18
29 %
876
348
348
348
348
348
0.425
12 %
1020
144
144
144
144
144
0.150
5%
1080
60
60
60
60
60
0.075
4%
1128
48
48
48
48
48
OPC
Added
Dust
Weight
of
bitumen
Total
Weight
of
sample
2%
1152
24
24
24
24
24
0.43 %
1157.2
5.2
5.2
5.2
5.2
5.2
-
-
60.63
67.04
73.53
80.08
86.70
-
-
1217.83
1224.24
1230.73
1237.28
1243.90
%
retained
@
5%
@
5.5 %
@
6%
@
6.5 %
@
7%
0
0
0
0
0
86
C)
Dry & Washed-Sieve Analysis Test for ACB28
Dry-Sieve analysis results
Table A4.1: Aggregate gradation & required weight of each aggregate size for
ACB28 mixture
Sieve Size
mm
37.5
28
20
14
10
5
3.35
1.18
0.425
0.15
0.075
Pan
Size^0.45
5.109
4.479
3.850
3.279
2.818
2.063
1.723
1.077
0.680
0.426
0.312
0
Percent
Passing
100 %
95 %
85 %
70 %
56 %
36 %
28 %
17 %
10 %
5%
4%
0%
Percent
retained
0%
5%
10 %
15 %
14 %
20 %
8%
11 %
7%
5%
1%
4%
∑ =100 %
Weight required
(gm)
0
60
120
180
168
240
96
132
84
60
12
48
∑ = 1200
Cumulative
Weight
0
60
180
360
528
768
864
996
1080
1140
1152
1200
Washed-Sieve analysis results
Table A4.2: Washed-sieve analysis result
Sample No.
Weight of sample before washing, A (g)
Weight of oven dry sample in air(after washing), B (g)
Amount of Dust coated on aggregate = A - B
1
2
1152.0
1152.0
1128.0
1131.1
24.00
20.90
Average =22.45gm
87
Percentage of required filler material for ACB28
Percentage of dust (Filler) = 4% (2% OPC + 2%filler).
2 % OPC (Ordinary Portland Cement) = 0.02×1200 = 24gm.
2 % filler = 0.02×1200 = 24gm.
Amount of dust coated on the aggregate ≈ 22.45gm.
Then, 24 - 22.45 = 1.55gm. filler that must be added to the total weight of aggregate.
Table A4.3: Final Aggregate gradation used to prepare Marshall samples for ACB28
after determining amount dust content coated an the aggregate
Sieve
Size
mm
37.5
0%
Cumulative
Weight of
agg.
0
28
5%
60
60
60
60
60
60
20
10 %
180
120
120
120
120
120
14
15 %
360
180
180
180
180
180
10
14 %
528
168
168
168
168
168
5.0
20 %
768
240
240
240
240
240
3.35
8%
864
96
96
96
96
96
1.18
11 %
996
132
132
132
132
132
0.425
7%
1080
84
84
84
84
84
0.150
5%
1140
60
60
60
60
60
0.075
1%
1152
12
12
12
12
12
OPC
Added
Dust
Weight
of
bitumen
Total
Weight
of
sample
2%
1176
24
24
24
24
24
0.1291%
1177.55
1.55
1.55
1.55
1.55
1.55
-
-
42.70
49.10
55.50
62.00
68.60
-
-
1220.25
1226.65
1233.1
1239.55
1246.15
%
retained
@
3.5 %
@
4.0 %
@
4.5 %
@
5.0 %
@
5.5 %
0
0
0
0
0
88
D)
Dry & Washed-Sieve Analysis Test for SMA14
Dry-Sieve analysis results
Table A5.1: Aggregate gradation & required weight of each aggregate size for
SMA14 mixture
Sieve Size
mm
25
19
12.5
9.5
4.75
2.36
0.6
0.3
0.075
Pan
Size^0.45
4.256
3.762
3.116
2.754
2.016
1.472
0.795
0.582
0.312
0
Percent
Passing
100
100 %
100 %
77.5 %
31.5 %
20 %
14 %
13.5 %
9%
0%
Percent
retained
100
0%
0%
22.5 %
46 %
11.5 %
6%
0.5 %
4.5 %
9%
∑ =100 %
Weight required
(gm)
100
0
0
270
552
138
72
6
54
108
∑ = 1200
Cumulative
Weight
0
0
0
270
822
960
1032
1038
1092
1200
Washed-Sieve analysis results
Table A5.2: Washed-sieve analysis result
Sample No.
Weight of sample before washing, A (g)
Weight of oven dry sample in air(after washing), B (g)
Amount of Dust coated on aggregate = A - B
1
2
1092
1092
1069.1
1071.5
22.9
20.5
Average = 21.7gm
89
Percentage of required filler material for SMA14
Percentage of dust (Filler) = 9% (Ortdinary Portland Cement).
9 % OPC (Ordinary Portland Cement) = 0.09*1200 = 108gm.
Amount of dust coated on the aggregate ≈ 21.7gm.
Then, 108 - 21.7 = 86.3gm OPC that must be added to the total weight of aggregate.
Table A5.3: Final Aggregate gradation used to prepare Marshall samples for SMA14
after determining amount dust content coated an the aggregate
Sieve
Size
mm
%
retained
25
4.256
Cumulative
Weight of
agg.
0
19
0%
12.5
@
5.0 %
@
5.5 %
@
6.0 %
@
6.5 %
@
7.0 %
0
0
0
0
0
0
0
0
0
0
0
0%
0
0
0
0
0
0
9.5
22.5 %
270
270
270
270
270
270
4.75
46 %
822
552
552
552
552
552
2.36
11.5 %
960
138
138
138
138
138
0.6
6%
1032
72
72
72
72
72
0.3
0.5 %
1038
6
6
6
6
6
0.075
OPC
Added
Dust
Weight
of
bitumen
Total
Weight
of
sample
4.5 %
1092
54
54
54
54
54
7.19 %
1178.3
86.3
86.3
86.3
86.3
86.3
0%
0
0
0
0
0
0
-
-
62.02
68.58
75.21
81.91
88.69
-
-
1240.32
1246.88
1253.51
1260.21
1266.99
90
E)
Dry & Washed-Sieve Analysis Test for SMA20
Dry-Sieve analysis results
Table A6.1: Aggregate gradation & required weight of each aggregate size for
SMA20 mixture
Sieve Size
mm
25
19
12.5
9.5
4.75
2.36
0.6
0.3
0.075
Pan
Size^0.45
4.256
3.762
3.116
2.754
2.016
1.472
0.795
0.582
0.312
0
Percent
Passing
0
100 %
90%
70 %
24 %
20 %
14 %
13.5 %
9%
Percent
retained
0
0%
10 %
20 %
46 %
4%
6%
0.5 %
4.5 %
9%
∑ =100 %
Weight required
(gm)
0
0
120
240
552
48
72
6
54
108
∑ = 1200
Cumulative
Weight
0
0
120
360
912
960
1032
1038
1092
1200
Washed-Sieve analysis results
Table A6.2: Washed-sieve analysis result
Sample No.
Weight of sample before washing, A (g)
Weight of oven dry sample in air(after washing), B (g)
Amount of Dust coated on aggregate = A - B
1
2
1092
1092
1072
1074.9
20.0
17.1
Average =18.55gm
91
Percentage of required filler material for SMA20
Percentage of dust (Filler) = 9% (Ortdinary Portland Cement).
9 % OPC (Ordinary Portland Cement) = 0.09*1200 = 108gm.
Amount of dust coated on the aggregate ≈ 18.55gm.
Then, 108 - 18.55 = 89.5gm OPC that must be added to the total weight of aggregate.
Table A6.3: Final Aggregate gradation used to prepare Marshall samples for SMA20
after determining amount dust content coated an the aggregate
Sieve
Size
mm
%
retained
19
0%
Cumulative
Weight of
agg.
0
12.5
10 %
9.5
@
5.0 %
@
5.5 %
@
6.0 %
@
6.5 %
@
7.0 %
0
0
0
0
0
120
120
120
120
120
120
20 %
360
240
240
240
240
240
4.75
46 %
912
552
552
552
552
552
2.36
4%
960
48
48
48
48
48
0.6
6%
1032
72
72
72
72
72
0.3
0.5 %
1038
6
6
6
6
6
0.075
OPC
Added
Dust
Weight
of
bitumen
Total
Weight
of
sample
4.5 %
1092
54
54
54
54
54
7.45 %
1181.5
89.5
89.5
89.5
89.5
89.5
0%
-
0
0
0
0
0
-
-
62.18
68.76
75.41
82.14
88.93
-
-
1243.68
1250.26
1256.91
1263.64
1270.43
92
3)
Percentage of Bitumen Contents and Required weight of Asphalt for
different mixtures
The following formula is used to calculate the weight of bitumen required at
each asphalt content:
% Asphalt content = [ W bitumen / (W bitumen + W aggregate)] x 100
For example, at 5% asphalt content for ACW10, the required weight of asphalt is :
5% = [ W bitumen / (W bitumen + 1152)] x 100 → W bitumen =60.63gm.
Table A7.1: Weight of bitumen at each bitumen content for ACW10
Bitumen Content
5.0 %
5.5 %
6.0 %
6.5 %
7.0 %
Weight aggregate (gm)
1152
1152
1152
1152
1152
Weight of bitumen (gm)
60.63
67.04
73.53
80.08
86.70
Table A7.2: Weight of bitumen at each bitumen content for ACW14
Bitumen Content
4.5 %
5.0 %
5.5 %
6.0 %
6.5 %
Weight aggregate (gm)
1157.2
1157.2
1157.2
1157.2
1157.2
Weight of bitumen (gm)
54.52
60.90
67.35
73.86
80.44
Table A7.3: Weight of bitumen at each bitumen content for ACB28
Bitumen Content
Weight aggregate (gm)
Weight of bitumen (gm)
3.5 %
4.0 %
4.5 %
5.0 %
5.5 %
1177.55 1177.55 1177.55 1177.55 1177.55
42.70
49.06
55.48
61.97
68.53
93
Table A7.4: Weight of bitumen at each bitumen content for SMA14
Bitumen Content
5.0 %
Weight aggregate (gm)
1178.3
Weight of bitumen (gm)
62.02
5.5 %
6.0 %
6.5 %
7.0 %
1178.3
1178.3
1178.3
1178.3
68.58
75.21
81.91
88.69
Table A7.5: Weight of bitumen at each bitumen content for SMA20
Bitumen Content
5.0 %
5.5 %
6.0 %
6.5 %
7.0 %
Weight aggregate (gm)
1181.5
1181.5
1181.5
1181.5
1181.5
Weight of bitumen (gm)
62.18
68.76
75.41
82.14
88.93
94
APPENDIX B
1)
Bulk Specific Gravity of coarse and fine Aggregates
A)
ACW10
Table B1.1: Bulk Specific Gravity of Coarse Aggregate
Sample
Weight Oven-dry aggregate,
A (gm)
1
2
3
1045.3
1045.6
1044.50
Weight saturated surface dry aggregate,
B (gm)
1056.9
1054.2
1053.70
Weight aggregate in water,
C (gm)
650.7
651.7
650.00
Bulk Specific Gravity (S.G)bulk
= A/(B-C)
2.573
2.598
2.587
Average(S.G)bulk = 2.586
Bulk SSD Specific Gravity (S.G)ssd
= B/(B-C)
2.602
2.619
2.610
Average (S.G)ssd = 2.610
Apparent Specific Gravity (S.G)app
= A(A-C)
2.649
2.654
2.648
Average (S.G)app = 2.650
Water absorption (%)
= 100(B-A)/A
1.110
0.822
0.881
Average = 0.938 %
95
Table B1.2: Bulk Specific Gravity of Fine Aggregate
Sample
1
2
3
Pycnometer Weight
280.7
281.4
294.1
Weight of oven dry material,
A (gm)
493.3
491.2
493.6
Weight of SSD aggregate ,
S (gm)
500.2
500.4
501.1
Weight of Pycnometer filled with water,
B (gm)
875.5
877.1
878.4
Weight of Pycnometer with specimen and
water to the calibration mark,
C (gm)
1172.3
1184.7
1189.1
Bulk Specific Gravity (S.G)bulk
=A/(B+S-C)
2.425
2.548
2.592
Bulk SSD Specific Gravity (S.G)ssd
=S/(B+S-C)
2.459
Apparent Specific Gravity (S.G)app
=A/(A+B-C)
2.510
2.675
2.699
Average (S.G)app = 2.628
1.399
1.873
1.519
Average = 1.597 %
Water absorption (%)
=100(S-A)/A
Average(S.G)bulk = 2.522
2.595
2.632
Average (S.G)ssd = 2.562
Specific Gravity of Blend
S.G (blend)
100
=
(%coarse Agg./SG coarse) + (%fine Agg./SG fin e) + (%filler/SG filler)
S.G (blend)
100
=
(35 / 2.586) + (63 / 2.522) + (2 / 2.98)
=
2.551
96
B)
ACW14
Due to using the same source of aggregate for ACW10,ACW14 and ACB28,
specific gravity of coarse and fine aggregate have been considered to be the same for
the three mixtures which is 2.586 for Coarse aggregate and 2.522 for fine aggregate.
Specific Gravity of Blend
S.G (blend)
=
100
(%coarse Agg./SG coarse) + (%fine Agg./SG fin e) + (%filler/SG filler)
S.G (blend)
=
100
(44 / 2.586) + (54/ 2.522) + (2 / 2.98)
=
C)
2.557
ACB28
Due to using the same source of aggregate for ACW10,ACW14 and ACB28,
specific gravity of coarse and fine aggregate has been considered the same which are
2.586 for Coarse aggregate and 2.522 for fine aggregate.
Specific Gravity of Blend
S.G (blend)
=
100
(64 / 2.586) + (34/ 2.522) + (2 / 2.98)
=
2.570
97
D)
SMA14
Table B1.3: Bulk Specific Gravity of Coarse Aggregate
1
2
Weight Oven-dry aggregate, A (gm)
995.4
995.9
Weight saturated surface dry aggregate, B(gm)
1005.3
1005.0
Weight aggregate in water, C (gm)
623.9
623.8
2.610
2.613
Sample
Bulk Specific Gravity (S.G)bulk = A/(B-C)
Average(S.G)bulk = 2.611
2.636
Bulk SSD Specific Gravity (S.G)ssd = B/(B-C)
Average (S.G)ssd = 2.636
2.679
Apparent Specific Gravity (S.G)app = A/(A -C)
2.676
Average (S.G)app = 2.678
0.995
Water absorption (%) = 100(B-A)/A
2.636
0.914
Average = 0.954 %
Table B1.3: Bulk Specific Gravity of Fine Aggregate
1
2
Pycnometer Weight
293.3
-
Weight of oven dry material, A (gm)
495.2
-
Weight of SSD aggregate , S (gm)
500.4
-
Weight of Pycnometer filled with water, B (gm)
Weight of Pycnometer with specimen and water
to the calibration mark, C (gm)
877.2
-
1194.7
-
2.707
-
Sample
Bulk Specific Gravity (S.G)bulk = A/(B+S-C)
Average(S.G)bulk = 2.707
2.736
Bulk SSD Specific Gravity (S.G)ssd = S/(B+S-C)
Average (S.G)ssd = 2.736
2.787
Apparent Specific Gravity (S.G)app = A/(A+B-C)
-
Average (S.G)app = 2.787
1.050
Water absorption (%) = 100(S-A)/A
-
-
Average = 1.050 %
98
Specific Gravity of Blend for SMA14
S.G (blend)
100
=
(%coarse Agg./SG coarse) + (%fine Agg./SG fin e)
S.G (blend)
100
=
(68.5 / 2.611) + (31.5 / 2.707)
=
E)
2.641
SMA20
S.G (blend)
100
=
(%coarse Agg./SG coarse) + (%fine Agg./SG fin e)
S.G (blend)
100
=
(76 / 2.611) + (24 / 2.707)
=
2.634
99
APPENDIX C
Maximum Specific Gravity of Loose Mixtures
A)
ACW10
Table C1.1: Maximum specific gravity of loose ACW10 mixture
Sample
Asphalt content of the mix, ( % bit )
Specific gravity of Aspahlt, S.G(bit)
1
6.00
1.03
2
6.00
1.03
Weight of Bowl in air, A (g)
Weight of Bowl in water, B (g)
Weight of Bowl & sample in air, C (g)
Weight of sample , D (g)
Weight of Bowl & sample in water, E (g)
2210.5
1393.7
3426.0
1215.5
2103.7
2210.8
1393.7
3425.8
1215.0
2101.8
Maximum specific gravity of Mix, Gmm (T.M.D)
=D/(D+B-E)
2.405
2.397
Average = 2.401
Effective specific gravity of aggregate, S.G eff
=(100-%bit) / {(100/Gmm)-(%bit/S.Gbit)}
2.628
2.619
Average = 2.6236
100
B)
ACW14
Table C1.2: Maximum specific gravity of loose ACW14 mixture
Sample
Asphalt content of the mix, ( % bit )
Specific gravity of Aspahlt, S.G(bit)
1
2
5.50
1.03
5.50
1.03
Weight of Bowl in air, A (g)
Weight of Bowl in water, B (g)
Weight of Bowl & sample in air, C (g)
Weight of sample , D (g)
Weight of Bowl & sample in water, E (g)
2210.1
1393.7
3815.3
1605.2
2332.8
2210.3
1393.7
3816.5
1606.2
2333.9
Maximum specific gravity of Mix, Gmm (T.M.D)
=D/(D+B-E)
2.410
2.412
Average = 2.411
Effective specific gravity of aggregate, S.G eff
=(100-%bit) / {(100/Gmm)-(%bit/S.Gbit)}
2.614
2.616
Average = 2.6148
C)
ACB28
Table C1.3: Maximum specific gravity of loose ACB28 mixture
Sample
Asphalt content of the mix, ( % bit )
Specific gravity of Aspahlt, S.G(bit)
1
4.50
1.03
2
4.50
1.03
Weight of Bowl in air, A (g)
Weight of Bowl in water, B (g)
Weight of Bowl & sample in air, C (g)
Weight of sample , D (g)
Weight of Bowl & sample in water, E (g)
2394.7
1393.4
4797.1
2402.4
2812.1
2210.0
1393.0
4729.1
2519.1
2883.6
Maximum specific gravity of Mix, Gmm (T.M.D)
=D/(D+B-E)
2.442
2.449
Average = 2.446
Effective specific gravity of aggregate, S.G eff
=(100-%bit) / {(100/Gmm)-(%bit/S.Gbit)}
2.611
2.619
Average = 2.615
101
D)
SMA14
Table C.4: Maximum specific gravity of loose SMA14 mixture
Sample
Asphalt content of the mix, ( % bit )
Specific gravity of Aspahlt, S.G(bit)
1
6.00
1.03
2
6.00
1.03
Weight of Bowl in air, A (g)
Weight of Bowl in water, B (g)
Weight of Bowl & sample in air, C (g)
Weight of sample , D (g)
Weight of Bowl & sample in water, E (g)
2210.1
1392.8
3728
1517.9
2285.2
2210.1
1392.7
3765
1554.9
2300.2
Maximum specific gravity of Mix, Gmm (T.M.D)
=D/(D+B-E)
2.427
2.402
Average = 2.414
Effective specific gravity of aggregate, S.G eff
=(100-%bit) / {(100/Gmm)-(%bit/S.Gbit)}
2.657
2.625
Average = 2.641
E)
SMA20
Table C.5: Maximum specific gravity of loose SMA20 mixture
Sample
Asphalt content of the mix, ( % bit )
Specific gravity of Aspahlt, S.G(bit)
1
6.00
1.03
2
6.00
1.03
Weight of Bowl in air, A (g)
Weight of Bowl in water, B (g)
Weight of Bowl & sample in air, C (g)
Weight of sample , D (g)
Weight of Bowl & sample in water, E (g)
2210.0
1393.0
4247.0
2037.0
2590.6
2210.1
1392.8
4268.4
2058.3
2595.7
Maximum specific gravity of Mix, Gmm (T.M.D)
=D/(D+B-E)
2.427
2.406
Average = 2.416
Effective specific gravity of aggregate, S.G eff
=(100-%bit) / {(100/Gmm)-(%bit/S.Gbit)}
2.657
2.631
Average = 2.644
102
APPENDIX D
MARSHALL MIX DESIGN RESULTS
1) ACW10
103
2) ACW14
104
3) ACB28
105
4) SMA14
106
5) SMA20
107