Table Of ContentINVESTIGATION OF LABORATORY ASPHALT AGING PROCESSES FOR
DEVELOPMENT OF AN EFFECTIVE PROCEDURE TO CHARACTERIZE
ASPHALT DURABILITY
CHUI-TE CHIU
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1994
Dedicated to my parents, sisters, brothers, and wife
for their love and support.
ACKNOWLEDGEMENTS
The author wishes to express immeasurable appreciation to his advisor and
supervisory committee chair. Dr. Mang Tia, for his patience and advice throughout his
graduate school career. Without his support and guidance this work would not have been
possible.
Special thanks go to Dr. Byron E. Ruth, who has kindly served as the cochairman
ofhis supervisory committee, for his advice and encouragement throughout the
challenging stages ofthis study. Sincere thanks are given to the rest ofhis supervisory
committee. Dr. David Bloomquist, Dr. Andre I. Khuri, and Mr. Gale C. Page, from whom
he has benefitted tremendously.
Thanks are also extended to the Florida Department ofTransportation (FDOT) for
providing the financial support and to the FDOT Materials Office personnel, particularly
Mr. Kenneth H. Murphy, Randy C. West, Edward Leitner, Toby Dillow, Glen Schiller,
and Aaron Turner, for their help and for kindly sharing their experience.
The author would like to thank the University ofFlorida and the Department of
Civil Engineering faculty, staff, and students for making his educational experience here so
meaningful and rewarding both academically and socially. His thanks also go to Mr.
Danny Richardson, engineer ofthe structural and materials laboratory, for his assistance in
maintaining the testing equipment. The graduate students in the hardworking materials
111
group, particularly Shin-Che Huang, Patrick B. Upshaw, Chuang-Tsair Shih, Tim
Wattleworth, Ming-Gin Lee, and Bob Casper, will always be remembered for their help
and exchange ofknowledge through brainstorming discussions.
Finally, the author is deeply indebted to his family and his wife, Win-Jane, fortheir
love, encouragement, and understanding throughout his studies.
IV
. .
TABLE OF CONTENTS
page
ACKNOWLEDGEMENTS
LIST OF TABLES
. . .
LIST OF FIGURES
. . . .
ABSTRACT
. .
CHAPTERS
INTRODUCTION
1
1.1 Background
. .
1.2 Study Objectives
1.3 Scope ofStudy
LITERATURE REVIEW 6
2
2.1 Pavement Failure Caused by Asphalt Aging 6
2.2 The Mechanism ofAsphalt Aging 8
2.2.1 Asphalt Chemistry 9
2.2.2 Loss ofOily Components 10
2.2.3 Oxidation 11
2.3 Evaluation ofAsphalt Aging Characteristics 14
2.3.1 Mechanical Tests on Asphalt Concrete 14
2.3.2 Chemical Composition Tests on Asphalt Binders 16
2.3.3 Physical Property Tests on Asphalt Binders 18
2.4 Recovery ofAsphalt Binders from Aged Mixtures 26
2.5 Laboratory Simulation ofAsphalt Aging 31
RESEARCH PROGRAM AND INSTRUMENTATION 38
38
3.1 Introduction
3.2 Asphalt Extraction and Recovery Methods 38
V
3.3 Investigation ofDifferent Aging Methods on Asphalt Cements. . . 43
3.3.1 Extended TFOT 47
3.3.2 Ultraviolet Chamber 47
3.3.3 California Tilt Oven 50
3.3.4 Pressure Aging Vessel 50
3.4 Investigation on Aging ofAsphalt Mixtures 53
3.4.1 Aging ofAsphalt Mixtures in the Laboratory 53
3.4.2 Aging ofMarshall Samples under Natural Sunlight . . . . 55
3.5 Investigation on the Aging Characteristics ofModified
Asphalt Binders 57
3.6 Equipment for Binder Tests 57
3.6.1 Cannon Schweyer Constant Stress Rheometer 59
3.6.2 Brookfield Rheometer 63
3.6.3 Infrared Spectrophotometer 67
3.7 Methodology for Analysis ofData 69
4 ASPHALT EXTRACTION AND RECOVERY METHOD 71
4.1 Sampling and Testing 71
72
4.2 Test Results
4.3 Summary ofFindings 76
COMPARISON OF DIFFERENT AGING METHODS
5
ON ASPHALT BINDERS 78
78
5.1 Introduction
5.2 Statistical Model 78
5.3 Test Results 80
5.3.1 Weight Change 80
5.3.2 Penetration 83
5.3.3 Carbonyl Ratio 88
5.3.4 Absolute Viscosity 93
5.3.5 Constant Stress Viscosity 100
5.3.6 Temperature Susceptibility 109
5.4 Comparison ofEvaluation Parameters 120
.122
5.5 Advantages and Disadvantages ofDifferent Aging Processes
5.6 Summary ofFindings 125
aging CHARACTERISTICS OF MODIFIED BINDERS 128
6
6.1 Introduction 128
6.2 Materials and Laboratory Procedures 128
6.3 Test Results 132
vi
6.4 Use ofBrookfield Rheometer for Measuring Viscosity at 60 °C . 143
6.5 Comparison ofTFOT and RTFOT in the Process ofPAV . 145
6.6 Summary ofFindings 150
INVESTIGATION OF AGING OF ASPHALT MIXTURES .... 152
7
152
7.1 Introduction
7.2 Laboratory Aging on Mixtures 153
7.3 SHRP Proposed Aging Procedures on Mixtures 157
7.4 Marshall Samples Aged under Natural Sunlight 160
7.5 Evaluation ofAge Hardening Model 166
7.6 Summary ofFindings 180
CONCLUSIONS AND RECOMMENDATIONS 183
8
8.1 Conclusions 183
8.2 Recommendations 187
APPENDICES
A RESULTS OF BINDER TESTS IN COMPARISON OF
DIFFERENT AGING METHODS ON BINDERS 190
B RESULTS OF BINDER TESTS IN THE AGING
CHARACTERISTICS OF MODIFIED BINDERS 196
C BROOKFIELD RHEOMETER TEST DATA AND THEIR
CORRESPONDING ABSOLUTE VISCOSITY 202
D TEST RESULTS IN COMPARISON OF TFOT AND RTFOT
IN THE PROCESS OF PRESSURE AGING VESSEL 206
REFERENCES 207
BIOGRAPHICAL SKETCH 214
Vll
LIST OF TABLES
Page
Tables
2-1 Relationship between Asphalt Properties and Field Performance,
1950 to present '
2-
23--2 Solvents Used in ASTM D2172 28
3-
2-3 Extraction Methods Used in ASTM D2172 29
4-
2-4 Laboratory Accelerated Tests and Evaluation Methods to Determine
32
Asphalt Durability
4-
5 Age Conditioning Procedures Evaluated in SHRP Related Studies 35
5-
1 Asphalt Binders Used in this Study 45
2 Laboratory Asphalt Aging Processes Investigated in this Study 46
Absolute Viscosities and Penetrations ofthe Asphalts Recovered by the
1
Different Combinations ofMethods 23
4-2 Results ofANOVA and Duncan's Multiple Range Tests on
Penetration Data 24
3 Results ofANOVA and Duncan's Tests on Absolute Viscosity Data 25
Weight Change ofDifferent Asphalt Cements after the Process of
1
TFOT, CTO, and PAV 81
5-2 Percent Penetration Retained ofResidues ofFive Asphalts at Different
Aging Conditions 84
5-3 Results ofANOVA and Duncan's Multiple Range Test on the
Percent Penetration Retained in the Comparison ofDifferent
Aging Methods on Asphalt Cements 86
Vlll
9
5-4 Carbonyl Ratio Index ofResidues ofthe Five Asphalts after
the 17 Aging Processes 89
5-5 Results ofANOVA and Duncan's Multiple Range Test on the
Carbonyl Ratio Index in the Comparison ofDifferent Aging
Methods on Asphalt Cements 91
5-6 Aging Index at 60 °C ofResidues ofthe Five Asphalts Aged by
the 17 Aging Processes 94
5-7 Results ofANOVA and Duncan's Multiple Range Test on the Logarithm
ofAging Index at 60 °C in the Comparison ofDifferent Aging Methods
on Asphalt Cements 97
5-8 Aging Index at 25 °C ofResidues ofthe Five Asphalts Aged by
the 17 Aging Processes ^91
5-9 Aging Index at 5 °C ofResidues ofthe Five Asphalts Aged by
the 17 Aging Processes 192
5-10 Results ofANOVA and Duncan's Multiple Range Test on the Logarithm
ofAging Index at 25 °C in the Comparison ofDifferent Aging Methods
on Asphalt Cements 195
5-1 1 Results ofANOVA and Duncan's Multiple Range Test on the Logarithm
ofAging Index at 5 °C in the Comparison ofDifferent Aging Methods
on Asphalt Cements 197
5-12 Temperature Susceptibility Parameter, PfW' ofthe Five
Asphalts and their Residues Aged by the 17 Aging Methods Ill
5-13 Temperature Susceptibility Parameter, VTS (60-5), ofthe Five
Asphalts and their Residues Aged by the 17 Aging Methods 112
5-14 Results ofLinear Regression Analysis on the Viscosity-Temperature
CTO
Relationships ofthe Five Asphalts before and after aging
for 168 hours 1 1
5-15 Comparison ofthe R-Square ofthe Models and Coefficient of
Variance ofthe Different Parameters as Determined from the
.Analysis ofVariance 123
IX
5-16 Summary ofComparison ofDifferent Aging Methods
Investigated in this Study 124
Summary ofResults ofTests on the CTO Residues ofModified Asphalts 133
6-2 Summary ofResults ofTests on the PAV Residues ofModified Asphalts 134
.
6-3 Results ofANOVA and Duncan's Multiple Range Test on the
Logarithm ofAging Index at 60 °C ofModified Asphalts
Aged by the CTO Processes
6-4 Results ofANOVA and Duncan's Multiple Range Test on the
Logarithm of Aging Index at 60 °C ofModified Asphalts
Aged by the PAV Processes 141
6-5 Temperature Susceptibility Parameters, PVN' (25-60) and
VTS(60-5) ofthe Modified Binders and their Residues
Aged by CTO and PAV Processes 144
6-6 Aging Indices at 60 °C ofthe Residues aged by Different
Combinations ofRTFOT/TFOT and PAV Processes
(Brookfield Rheometer Data) 148
Results ofTests on the Recovered Binders from the Loose Mixtures
Aged in the UV Chamber and Forced-Draft Oven 154
The Relative Ranking ofAging Severity ofResidues ofthe Five Asphalts
aged by Different Laboratory Aging Processes 156
Results ofTests on Recovered Binders from the Mixtures Aged in
the SHRP Proposed Procedures 159
7-4 Results ofTests on Recovered Binders from the Marshall Samples Aged
under Natural Sunlight 163
The Aging Indices at 60 °C and Relative Severity Ranking ofResidues
Recovered from Marshall Samples Aged under Natural Sunlight 165
7-6 Summary ofResults ofRegression Analyses Using Equation 15 to Relate
Asphalt Viscosity to Pavement Age for Different Projects 174
7-7 Comparison ofthe Predicted Viscosities by Using Equation 15 with
Measured Values in Different Projects 176
X
