the aggregate degradation characteristics of...
TRANSCRIPT
THE AGGREGATE DEGRADATION CHARACTERISTICS OF STONE MASTIC
ASPHALT (SMA) MIXTURES
NORLIZA BINTI MOHD AKHIR
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
NOVEMBER 2006
iii
“Dedicated to my beloved father, Mohd Akhir and mother, Musalmiah,
my sisters, Mafizah, Fadilah, Sakinah and Norazalia,
my brothers, Mohd Shahizan and Mohd Saifuddin,
and to a special person…
for their love, support and patience are awesome”
“Also not forgotten to all my colleagues,
Elizabeth, Zanariah, Masyitah, Nordiana and Norhidayah,
for their assistance and encouragements towards the success of this study”
iv
ACKNOWLEDGEMENT
In the name of Allah S.W.T, I would like to express my gratefulness to Him
for giving me strength to finish my project. In preparing this project report, I was in
contact with many people who have contributed towards my understanding and
thoughts.
I wish to express my sincere appreciation to my main project supervisor, Dr.
Mohd Rosli bin Hainin, for encouragement, guidance and critics. I am also very
thankful to my co-supervisor, Tn. Hj. Che Ros bin Ismail, for his guidance, advices
and motivation. Without their continued support and interest, this project report
would not have been the same as presented here.
I am also indebted to all staffs of Highway and Transportation Laboratory of
UTM, Mr. Abdul Rahman, Mr. Suhaimi, Mr. Azman and Mr. Ahmad Adin, for their
assistance and helpfulness during my project laboratory work. Special thanks also to
Mr. Zaini, from Hanson Quarry Product for supplying me the project laboratory
materials.
My fellow postgraduate students should also be recognized for their support.
My sincere appreciation also extends to all my colleagues and others who have
provided assistance at various occasions. Their views and tips are useful indeed.
Unfortunately, it is not possible to list all of them in this limited space.
v
ABSTRACT
Stone Mastic Asphalt (SMA) mixtures are designed to have a high coarse
aggregate content and stone-on-stone contact which results in more stress on the
coarse aggregate particles during compaction and traffic loads. For that reason,
aggregates tend to break down more in SMA mixtures than in conventional dense-
graded mixtures. Aggregate degradation during compaction and traffic loading may
cause changes in the original gradation and thus may also affect the volumetric
parameters of SMA mixtures. The main objective of this study was to determine the
degree of aggregates degradation in SMA mixtures due to compaction process.
Aggregates with two Nominal Maximum Aggregates Size (NMAS) which
designated as SMA14 and SMA20 were compacted using the effort of 50 blows of
Marshall Hammer and 100 gyrations of Superpave Gyratory Compactor (SGC). The
verified samples were then prepared and extracted using Centrifuge Method. The
same procedure was also performed for the cored samples. The comparisons of
gradation of cored samples with the laboratory samples were evaluated to examine
the aggregate degradation with respect to different compaction efforts. The
relationship between aggregate degradation and influencing factor such as
compaction efforts, and volumetric properties were investigated. Aggregate
degradation by the Marshall Hammer was found to be significantly higher than
degradation by the SGC. Voids in mineral aggregate (VMA) of either compaction
methods decrease or almost the same when aggregate degradation is not significant.
SGC methods can be selected to represent the field roller that result in similar trend
of aggregate degradation.
vi
ABSTRAK
Campuran Stone Mastic Asphalt (SMA) direka bentuk untuk mempunyai
kandungan aggregat kasar yang tinggi serta daya ikatan antara aggregat (stone-on-
stone contact). Aktiviti pemadatan di tapak dan pembebanan lalu lintas akan
memberikan tekanan terhadap partikel aggregat kasar tersebut. Oleh yang demikian,
aggregat di dalam campuran SMA lebih cenderung untuk pecah berbanding
campuran panas bergred tumpat biasa. Kesan ini menyebabkan perubahan
penggredan asal aggregat dan akhirnya mempengaruhi parameter volumetrik
campuran SMA. Objektif utama kajian ini ialah untuk menentukan tahap pecahan
aggregat di dalam campuran SMA yang disebabkan oleh proses pemadatan di
makmal. Dua saiz aggregat maksimum nominal (NMAS) yang direka bentuk
sebagai SMA14 dan SMA20 telah dipadat dengan 50 hentakan menggunakan Tukul
Marshall dan 100 putaran oleh Superpave Gyratory Compactor (SGC). Sampel-
sampel yang telah direka bentuk pada kandungan bitumen optimum disediakan dan
kemudiannya diekstrak dengan Kaedah Emparan. Prosedur sama turut dilakukan ke
atas sampel tebukan dari tapak. Perbandingan penggredan di antara sampel tebukan
dan makmal dinilai untuk menentukan pecahan aggregat terhadap kaedah pemadatan
yang berlainan. Hubungan di antara tahap pecahan aggregat dan faktor-faktor yang
mempengaruhi seperti jenis pemadatan, dan ciri-ciri volumetrik aggregat dikaji.
Hentakan Tukul Marshall didapati memecahkan aggregat lebih banyak berbanding
putaran oleh SGC. VMA bagi setiap kaedah pemadatan berkurang atau sama apabila
pemecahan aggregat tidak ketara. Kaedah SGC dipilih untuk mewakili pemadat
tapak kerana mempunyai ciri-ciri pemadatan yang sama seperti pemadat tapak.
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TABLE OF CONTENTS
CHAPTER TITLE PAGE
DECLARATION OF THE STATUS OF THESIS
SUPERVISOR’S DECLARATION
TITLE PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF ABBREVIATIONS/SYMBOLS xiv
LIST OF APPENDICES xv
1 INTRODUCTION 1
1.1 Introduction 1
1.2 Problem Statement 2
1.3 Objectives of the Study 3
1.4 Scope of the Study 3
1.5 Importance of the Study 4
2 LITERATURE REVIEW 5
2.1 Introduction 5
2.2 History of SMA 6
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2.3 Advantages of SMA 8
2.4 Disadvantages of SMA 9
2.5 Composition of SMA 10
2.6 Aggregate Characteristics 11
2.6.1 Relative Density 13
2.6.2 Aggregate Hardness 13
2.6.3 Flat and Elongated Particles 14
2.7 Mortar 14
2.7.1 Asphalt Binder 15
2.7.2 Mineral Filler 15
2.7.3 Stabilizing Additives 16
2.8 Mixture Design Overview 17
2.9 Mix Design Method 18
2.9.1 Marshall Method 18
2.9.2 Superpave Mix Design 19
2.9.2.1 Superpave Laboratory
Compaction 19
3 METHODOLOGY 21
3.1 Introduction 21
3.2 Laboratory Work Procedure 22
3.3 Sieve Analysis 23
3.3.1 Dry Sieve Analysis (For Fine and
Coarse Aggregate) 23
3.3.2 Washed Sieve Analysis (For Mineral
Filler) 25
3.3.3 Aggregate Gradation 27
3.4 Determination of Specific Gravity for
Aggregate 27
3.4.1 Coarse Aggregate 28
3.4.2 Fine Aggregate 29
3.5 Marshall Mix Design Method 31
3.5.1 Procedure 31
3.5.2 Apparatus 31
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3.5.3 Marshall Specimen Preparation 32
3.5.4 Marshall Stability and Flow Tests 34
3.5.5 Theoretical Maximum Density
(TMD) Test 36
3.5.6 Analysis of Data 39
3.5.6.1 Analysis of Bulk Specific
Gravity 39
3.5.6.2 Analysis of Void in Mineral
Aggregate (VMA) 41
3.5.6.3 Analysis of Air Void in the
Compacted Mix (VIM) 41
3.5.6.4 Analysis of Void Filled with
Bitumen (VFB) 42
3.5.7 Determination of Optimum Bitumen
Content 42
3.6 Superpave Mix Design 43
3.6.1 Apparatus 43
3.6.2 Procedures 43
3.6.3 Sample Preparation 44
3.6.4 Determination of Optimum Bitumen
Content 45
3.7 Binder Draindown Test 46
3.7.1 Apparatus 47
3.7.2 Test Procedure 48
3.7.3 Calculation 48
3.8 Bitumen Extraction Test 49
3.8.1 Apparatus 49
3.8.2 Test Procedure 50
3.8.3 Sieve Analysis of Extracted Aggregate 51
4 RESULTS AND DISCUSSIONS 52
4.1 Introduction 52
4.2 Sieve Analyses 52
4.2.1 Aggregate Gradation 53
x
4.2.2 Wet Sieve Analysis 55
4.3 Specific Gravity of Aggregate 55
4.3.1 Coarse Aggregate 56
4.3.2 Fine Aggregate 56
4.3.3 Filler 56
4.3.4 Specific Gravity of Blended Aggregate 56
4.4 Specific Gravity of Bitumen 57
4.5 Marshall and Superpave Results 57
4.6 Binder Draindown Test Results 58
4.7 Extraction and Sieve Analysis 59
4.8 Aggregate Degradation 59
4.8.1 Aggregate Degradation by Compaction 59
4.8.2 Effect on Volumetric Properties 62
5 CONCLUSIONS AND RECOMMENDATIONS 63
5.1 Conclusions 63
5.2 Recommendations 64
REFERENCES 65
APPENDICES A – J 68-87
xi
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Coarse aggregate quality requirements 12
2.2 Fine aggregate quality requirements 12
3.1 SMA mix requirements 22
3.2 Gradation limit for SMA 27
3.3 Minimum sample size requirement for maximum
theoretical specific gravity (ASTM D 2041) 38
3.4 Superpave gyratory compactive effort 45
4.1(a) Percentage aggregate passing on each sieve size
for SMA14 mix design 54
4.1 (b) Percentage aggregate passing on each sieve size
for SMA20 mix design 55
4.2 Bulk specific gravity of aggregate 57
4.3 Mix design results 58
4.4 Degradation results 61
xii
LIST OF FIGURES
FIGURE NO. TITLE PAGE
2.1 Comparisons between SMA and conventional HMA 5
2.2 SMA aggregate skeleton 6
2.3 Fat spots 9
2.4 Major components of SMA mixtures 10
2.5 Rutting on pavement surface layer 11
2.6 Various grading curves 17
3.1 Flow chart for SMA laboratory process 24
3.2 Mechanical sieve shaker 25
3.3 Automatic compactor hammer 33
3.4 Marshall compression testing machine 34
3.5 Water bath for submerging sample 35
3.6 Apparatus for TMD test 37
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3.7 Apparatus for determination of bulk specific gravity 40
3.8 Superpave gyratory compactor 44
3.9 Draindown test apparatus 46
3.10 Dimension of wire basket 47
3.11 Bitumen extraction apparatus 50
4.1 (a) Gradation limit and design curve for SMA14 53
4.1 (b) Gradation limit and design curve for SMA20 54
4.2 (a) Gradation changes for SMA14 60
4.2 (b) Gradation changes for SMA20 60
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LIST OF ABBREVIATIONS/SYMBOLS
SMA Stone Mastic Asphalt
NAPA National Asphalt Pavement Association
SHRP Strategic Highway Research Program
SGC Superpave Gyratory Compactor
NMAS Nominal Maximum Aggregate Size
SMA14 Stone Mastic Asphalt with Nominal Maximum Aggregate Size of
12.5mm
SMA20 Stone Mastic Asphalt with Nominal Maximum Aggregate Size of
19mm
HMA Hot Mix Asphalt
FHWA Federal Highway Administration
ESAL Equivalent Standard Axle Load
LAAV Los Angeles Abrasion Value
ASTM American Society for Testing and Materials
JKR Jabatan Kerja Raya
VIM Voids in Mix
VMA Voids in Mineral Aggregate
OBC Optimum Bitumen Content
NCAT National Center for Asphalt Technology
AASHTO American Association of State Highway and Transportation Officials
SSD Saturated-surface-dry
TMD Theoretical Maximum Density
VFB Voids Filled with Bitumen
Gmb Bulk specififc gravity of compacted mix
Gsb Combined bulk specific gravity of total aggregate
Gmm Theoretical maximum density
xv
LIST OF APPENDICES
APPENDIX TITLE PAGE
A Aggregate size distribution and
determination of filler 68
B Specific gravity for coarse aggregate, fine
aggregate and blended aggregate 70
C Marshall test results 73
D Theoretical maximum density 75
E Determination of OBC at 4% air voids 77
F Superpave test results 78
G Determination of OBC at 4% air voids 79
H Results of sieve analysis on extracted
aggregate (after compaction) 80
I1 The t-test paired comparing both laboratory
compaction method 81
I2 The t-test paired comparing both laboratory
compactor and the field roller (for SMA20) 82
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J Photo for Laboratory Work 83
CHAPTER 1
INTRODUCTION
1.1 Introduction
Stone Mastic Asphalt (SMA), sometimes called Stone Mastic Asphalt
especially in Europe, is a gap-graded hot mix asphalt surfacing material (Pierce,
2000). SMA is an asphalt mixture initially developed in the 1980s in Europe as an
impervious wearing surface to provide rut resistant and durable pavement surface
layer. When SMA is first introduced in Europe, it is used in resisting the studded
tires effects rather than other type of hot mix asphalt (Roberts, Kandhal and Brown,
1996).
SMA is designed to resist deformation particularly rutting and maximize
durability by using as structural basis of stone-on-stone contact. SMA is
characterized by its high stone content and the voids of the structural matrix are filled
with high viscosity bituminous matrix. The high stone content of at least 70%
ensures stone-on-stone contact after compaction. The required degree of matrix
stiffness is achieved through the addition of crushed sand (Roberts, Kandhal and
Brown, 1996).
Because the aggregates are all in contact, rut resistance depends on aggregate
properties rather than asphalt binder properties. Since aggregates do not deform as
much as asphalt binder under load, this stone-on-stone contact significantly reduces
rutting. The SMA pavement offers other side benefits due to its high content of
2
coarse aggregate. SMA pavement surfaces are porous, thus reducing the
tire/pavement noise level as well as water spray and glare (NAPA, 1999).
However, SMA is generally more expensive than a typical dense-graded
HMA (about 20 - 25 percent) because it necessitates more durable aggregates, higher
asphalt content and typically, a modified asphalt binder and fibers (NAPA, 1999).
Durability was to be defined primarily through rutting and cracking measurements,
but was also to include other types of pavement deterioration (Schimiedlin and
Bischoff, 2002). In the right situations, it should be cost-effective because of its
performing better than the standard asphaltic concrete pavements in some important
areas, i.e., crack and distress generation thus increase rut resistance and improve
durability.
The mixture also entails higher mixing temperatures to provide greater
workability and longer mixing times at the plant due to the presence of modified
binder or mineral fiber ensuring proper distribution of the mineral fiber or adequate
coating of aggregates, and more intensive quality control at plant and on job site
(Watson and Jared, 1995). Based on its performance in term of durability and long
life service, the use of SMA is currently keep increasing in popularity among the
road authorities and the asphalt industry.
1.2 Problem Statement
SMA mixtures are designed to have high coarse aggregate content and stone-
to-stone contact which results in more stress on the coarse aggregate particles during
compaction and heavy traffic loads. As a result, the aggregates tend to degrade in
SMA mixtures than in conventional dense graded mixtures. Aggregate degradation
during compaction and heavy traffic loading may cause changes in the original
aggregate gradation, and thus may also affect the volumetric properties of SMA
mixtures.
Most work to date on SMA has been with Marshall Compactor but some
works needs to be done with a Gyratory Machine since the new SHRP gyratory will
3
eventually be used on SMA mixes. With the introduction of the Superpave system, it
is now significant for the mix designer who endeavoring to design stiffer, more rut-
resistant asphalt concrete pavements having the alternative of using the Superpave
Gyratory Compactor (SGC) for SMA mixtures.
The application of SMA is still new in Malaysia therefore the contractors had
little experience with this mixture at the time of construction. Since this study has
been done previously, but there has been little research conducted to relate with
Malaysia’s condition. Thus there is a need to study and determine the aggregate
degradation of SMA particularly experienced in Malaysia.
1.3 Objectives of the Study
The objectives of this study were:
a) to determine the degree of aggregate degradation in SMA mixtures during
the compaction process produced by 100 gyrations of the SGC and 50-
blow Marshall Hammer;
b) to determine the effect of the gradation changes on volumetric properties
of compacted SMA mixtures; and
c) to compare the aggregate degradation of compacted samples experienced
at field and laboratory.
1.4 Scope of the Study
The scope of the study focused on the effects of compaction methods and
aggregate gradation affecting the aggregate degradation in SMA. The mixtures with
the nominal maximum aggregate size (NMAS) of 12.5mm (designated as SMA14)
and 19mm (designated as SMA20) were studied. In designing mixtures, total of 36
specimens were prepared using Marshall Compaction Method with three specimens
4
for each of bitumen content of 5.0%, 5.5%, 6.0%, 6.5%, and 7.0% by Marshall
Hammer at compaction efforts of 50 blows per face.
The work done by NCAT (Brown and Mallick, 1994 and Brown et al., 1997)
indicated that 50 blows of the Marshall Hammer generated a density in SMA
mixtures approximately equal to 100 gyrations of the SGC. With the 100 gyrations
effort, total of 16 specimens were prepared using Superpave Compaction Method,
with two specimens gyrating by SGC at three bitumen contents of 6.0%, 6.5% and
7.0%. As a conclusion, the total of 64 specimens was prepared including the 12
specimens were designed for binder draindown test purpose.
The aggregate degradation afterward was determined by comparing the
changes in gradation of extracted aggregate with the original aggregate gradation.
To achieve the objectives, the scope started with literature search and review on the
information related to the aggregate degradation in Chapter 2 and extensive
laboratory testing according to specified procedure was explained detail in Chapter 3
respectively.
1.5 Importance of the Study
This study was carried out to quantify and compare the amount of aggregate
degradation for SMA mixtures produced by 100 gyrations of the SGC and 50-blow
Marshall Hammer. This study can be a reference to evaluate other studies according
to the two compactive effort performances in the pavement design. Contractors from
developing country such as Malaysia may have problem using SMA mix because of
lack of experience since this mix is considered as new mix for road pavement
compared to standard asphaltic concrete. This type of information would provide
valuable information to agencies who desire to construct SMA pavements.
65
REFERENCES
American Association of State Highway and Transportation Officials. (2001).
Practice for Superpave Volumetric Design for Hot Mix Asphalt (HMA).
Washington D.C. AASHTO PP28-1.
American Association of State Highway and Transportation Officials. (2000).
Determination of Draindown Characteristics in Uncompacted Asphalt Mixtures.
Washington D.C. AASHTO T305.
American Association of State Highway and Transportation Officials (2000).
Preparing and Determining the Density of Hot-Mix Asphalt (HMA) Specimens by
Means of the Superpave Gyratory Compactor. Washington, D. C., AASHTO T-
312.
American Society for Testing and Materials. (1992). Standard Method for Sieve
Analysis for Fine and Coarse Aggregate. Philadelphia, ASTM C 136.
American Society for Testing and Materials. (1992). Standard Test Method for
Materials Finer than 75-μm (No. 200) Sieve in Mineral Aggregates by Washing.
Philadelphia, ASTM C 117.
American Society for Testing and Materials. (1992). Standard Test Method for
Specific Gravity and Absorption of Coarse Aggregate. Philadelphia, ASTM C
127.
American Society for Testing and Materials. (1992). Standard Test Method for
Specific Gravity and Absorption of Fine Aggregate. Philadelphia, ASTM C 128.
American Society for Testing and Materials. (1992). Standard Test Method for Bulk
Specific Gravity and Density of Compacted Bituminous Mixtures Using Saturated
Surface-Dry Specimens. Philadelphia, ASTM D 2726.
American Society for Testing and Materials. (1992). Standard Test Method for
Theoretical Maximum Specific Gravity and Density of Bituminous Paving
Mixtures. Philadelphia, ASTM D 2041.
66
American Society for Testing and Materials. (1992). Standard Test Method for
Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus.
Philadelphia, ASTM D 1559.
American Society for Testing and Materials. (1992). Standard Test Method for
Quantitative Extraction of Bitumen from Bituminous Paving Mixtures.
Philadelphia, ASTM D 2172.
Atkins, H. N. (2003). Highway Materials, Soils and Concretes. Fourth Edition.
Upper Saddle River, New Jersey: Prentice Hall.
Balqis binti Abu Bakar (2006). Kajian Kebolehtelapan Campuran Poros di Makmal.
Universiti Teknologi Malaysia: Degree Project Report.
Brown, E. R. and Haddock, J. E. (1997). A Method to Ensure Stone-on-stone
Contact in Stone Matrix Asphalt Paving Mixtures. NCAT Report No. 97-2.
National Center for Asphalt Technology, Auburn, Alabama.
Brown, E. R. and Mallick, R. B. (1994). Stone Matrix Asphalt Properties Related to
Mixture Design. NCAT Report No. 94-2. National Center for Asphalt Technology,
Auburn, Alabama.
Brown, E. R. and Manglorkar, H. (1993). Evaluation of Laboratory Properties of
SMA Mixtures. NCAT Report No. 93-5. National Center for Asphalt Technology,
Auburn, Alabama.
Brown, E. R., Haddock, J. E., Mallick, R. B., and Todd, A. L. (1997). Development
of A Mixture Design Procedure for Stone Matrix Asphalt (SMA). NCAT Report
No. 97-3. National Center for Asphalt Technology, Auburn, Alabama.
Buchanan, M. S. (2000). Evaluation of the Effect Flat and Elongated Particles on The
Performance of Hot Mix Asphalt Mixes. NCAT Report No. 00-03. National Center
for Asphalt Technology, Auburn, Alabama.
Garber, N. J. and Hoel, L. A. (2002). Traffic and Highway Engineering. Third
Edition. United States of America: Brooks/Cole.
Hongbin, Xie and Watson, D. E. (2004). Lab Study on Degradation of SMA
Mixtures. 83rd Annual Meeting of TRB. Transportation Research Board,
Washington, D. C
Huang, Y. H. (2004). Pavement Analysis and Design. Second Edition. Upper Saddle
River, New Jersey: Prentice Hall.
Ibrahim, M. Asi (2005). Laboratory Comparison Study for the Use of Stone Matrix
Asphalt in Hot Weather Climates. Hashemite University, Jordan; Elsevier.
67
Jabatan Kerja Raya (JKR) (2005). Standard Specifications for Road Works. Kuala
Lumpur, Malaysia, JKR/SPJ/rev2005.
Kandhal, P. S., Parker, F. Jr. and Mallick, R. B. (1997). Aggregate Tests for Hot Mix
Asphalt: State of the Practice. NCAT Report No. 97-6. National Center for Asphalt
Technology, Auburn, Alabama.
Keunnen, T. (2003). Better Roads Magazine. Stone Matrix Asphalt is Catching on in
the U.S. United States of America.
Mangan, D. and Butcher, M. (2004). Technical Note 16 Stone Mastic Asphalt.
Australian Roads Research Board. Australia.
Moavenzadeh, F. and Goetz, W.H. (1963). Aggregate Degradation in Bituminous
Mixtures. Highway Research Record 24. HRB. National Research Council.
Washington D.C.
National Asphalt Pavement Association (NAPA). (1999). Designing and
Constructing SMA Mixtures: State-of-the-Practice, QIP 122.
Pierce, L. M. (2000). Stone Matrix Asphalt. WSDOT Report No. SR-524.
Washington State, United States of America.
Roberts, F. L., Kandhal, P. S. and Brown, E. R. (1996). Hot Mix Asphalt Materials,
Mixture Design and Construction. NAPA Research and Education Foundation,
Lanham, Maryland.
Robinson, R. and Thagesen, B. eds. (2004). Road Engineering For Development.
Second Edition. New Fetter Lane, London: Spon Press.
Schimiedlin, R. B. and Bischoff, D. L. (2002). Stone Matrix Asphalt The Wisconsin
Experience. Wisconsin Department of Transportation. Madison, United States of
America.
Watson, D. E. and Jared, D. (1995). Stone Matrix Asphalt: Georgia’s Experience.
Georgia Department of Transportation. Georgia, United States of America.
Wu, Y., Parker, F. Jr. and Kandhal, K. (1998). Aggregate Toughness/Abrasion
Resistance and Durability/Soundness Tests Related to Asphalt Concrete
Performance in Pavements. NCAT Report No. 98-4. National Center for Asphalt
Technology, Auburn, Alabama.