FHWA-RD-02-075
by
Kevin D. Stuart
Federal Highway Administration
Turner-Fairbank Highway Research Center
6300 Georgetown Pike
McLean, VA 22101-2296
TELEPHONE: (202) 493-3073
FAX: (202) 493-3161
Section
E. Cumulative Permanent Shear Strain
E. Cumulative Permanent Shear Strain
LIST OF FIGURES
Figure No.
1. French PRT rut depth at 70°C vs. high-temperature PG
2. French PRT rut depth at 70°C vs. high-temperature PG for all asphalt binders
3. French PRT rut depth at 70°C vs. G*/sind at 70°C for all asphalt binders
4. RSCH cumulative permanent shear strain vs. high-temperature PG of the asphalt binder
5. RSCH cumulative permanent shear strain at 70°C vs. RSCH cumulative permanent shear strain at 50°C
10. RSCH cumulative permanent shear strain at 70°C vs. high-temperature PG of the asphalt binder
11. RSCH cumulative permanent shear strain at 70°C vs. PG temperature based on 0.125 rad/s
13. Comparison of cumulative permanent shear strain using a log-log transformation
14. French PRT rut depth at 70°C vs. G*/sind of the asphalt binder at 70°C and 0.9 rad/s
15. French PRT rut depth at 70°C vs. G*/sind of the asphalt binder at 70°C and 10.0 rad/s
16. French PRT rut depth at 70°C vs. high-temperature PG
17. G*/sind at 0.9 rad/s vs. G*/sind at 10.0 rad/s
18. French PRT rut depth vs. asphalt binder cumulative permanent shear strain
LIST OF TABLES
Table No.
2. Cumulative permanent shear strain from RSCH for the mixtures with limestone aggregate
3. DSR data and French PRT rut depths at 6,000 wheel passes
4. Percent rut depth from the French PRT at 70°C and 6,000 wheel passes
5. DSR data and French PRT rut depths at 20,000 wheel passes
6. DSR data and RSCH data at 70°C and 50°C
7. Replicate cumulative permanent shear strains at 70°C
9. Coefficients of determination between RSCH and DSR properties
10. Cumulative permanent shear strain at 70°C
12. Replicate data for the French PRT at 6,000 wheel passes
13. RSCH cumulative permanent strains at 70°C and 5,000 cycles using two asphalt binder contents
Technical Report Documentation Page | |||
1. Report No. FHWA-RD-02-075 |
2. Government Accession No. | 3. Recipient's Catalog No. | |
4. Title and Subtitle UNDERSTANDING THE PERFORMANCE OF MODIFIED ASPHALT BINDERS IN MIXTURES: HIGH-TEMPERATURE CHARACTERIZATION |
5. Report Date | ||
6. Performing Organization | |||
7. Author(s) Kevin D. Stuart |
8. Performing Organization Report No. |
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9. Performing Organization Name and Address Office of Infrastructure Research and Development Federal Highway Administration 6300 Georgetown Pike McLean, VA 22101-2296 |
10. Work Unit No. (TRAIS) | ||
11. Contract or Grant No. In-House Report |
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12. Sponsoring Agency Name
and Address Office of Infrastructure Research and Development Federal Highway Administration 6300 Georgetown Pike McLean, Virginia 22101-2296 |
13. Type of Report and Period
Covered Final Report October 2000 - March 2002 |
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14. Sponsoring Agency Code | |||
15. Supplementary Notes FHWA Contact: Kevin D. Stuart, HRDI-11. Contractor personnel that worked on this study were Frank Davis, Susan Needham, Scott Parobeck, Naga Shashidhar, and Aroon Shenoy, SaLUT, 6300 Georgetown Pike, McLean, VA 22101-2296. |
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16. Abstract The first objective was to verify the findings of a previous study using a different aggregate. In the previous study, it was found that the Superpave high-temperature asphalt binder properties correlated to mixture rutting resistance with few outliers, and a change in high-temperature PG from 70 to 76 increased rutting resistance. However, the correlation between RSCH and asphalt binder G*/sind (delta) depended on DSR frequency. The data suggested that a low DSR frequency, such as 0.1 rad/s, might provide a better grading system than the standard DSR frequency of 10.0 rad/s. This would require a change in the current asphalt binder specification. A diabase aggregate was used in a previous study. The data using a second aggregate, a limestone aggregate, in combination with four of the asphalt binders, agreed with the findings from the diabase mixtures. The second objective was to retest the diabase mixtures at 70 degrees Celsius using RSCH. The test temperatures used in the previous study were 50 degrees Celsius for RSCH and 70 degrees Celsius for the French PRT. The polymer-modified asphalt binders had continuous high-temperature PG's ranging from 71 to 77. Therefore, it was recommended that the test temperature for RSCH be increased to 70 degrees Celsius. Again, the correlation between RSCH and G*/sind was dependent on DSR frequency. The data suggested that a low DSR frequency, such as 0.1 rad/s, might provide a better grading system. However, it is not known whether this finding applies to pavements, or is related to the accelerated nature of the RSCH test. Furthermore, G*/sind (delta) at 0.1 rad/s did not clearly provide a better correlation to RSCH than the high-temperature PG's of the asphalt binders. The degree of correlation between the French PRT and G*/sind at 70 degrees Celsius did not depend on DSR frequency, and there was only one outlier. A correlation between the French PRT and high-temperature PG provided no obvious outliers. No changes to the specification are recommended based on the French PRT results. |
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17. Key Words Superpave, asphalt binder specification, permanent deformation, Superpave Shear Tester, SST, French Pavement Rutting Tester, polymer-modified asphalt binders. |
18. Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service, Springfield, Virginia 22161. |
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19. Security Classif. (of this report) Unclassified |
20. Security Classif. (of this page) Unclassified |
21. No. of Pages 41 |
22. Price |
SI* (Modern Metric) Conversion Factors
This report documents the effects of polymer-modified asphalt binders on the rutting resistance of mixtures with diabase and limestone aggregate. It is part of a research study titled "Understanding the Performance of Modified Asphalt Binders in Mixtures." This study is partially funded through National Cooperative Highway Research Program (NCHRP) Project 90-07. The objective of NCHRP Project 90-07 is to determine if asphalt binder performance is captured by the Superpave asphalt binder specification developed under the 1987 through 1993 Strategic Highway Research Program, with an emphasis on evaluating the performances of mixtures containing polymer-modified asphalt binders with identical Superpave performance grades, but varied chemistries. Asphalt binder tests developed under NCHRP Project 09-10, titled "Superpave Protocols for Modified Asphalt Binders," are also being evaluated. NCHRP Project 09-10 was completed in February 2001.
This report will be of interest to highway personnel who use polymer-modified asphalt binders and Superpave. Overall, good correlations between the high-temperature properties of the asphalt binders and mixture rutting resistance were found, but the two laboratory mixture tests did not provide the same conclusions concerning which asphalt binders do not behave as expected. Full-scale pavement tests are needed to determine this.
T. Paul Teng, P.E. Director, Office of Infrastructure Research and Development |
NOTICE
This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification, or regulation.
The U.S. Government does not endorse products or manufacturers. Trade and manufacturers=
names appear in this report only because they are considered essential to the
object of the document.
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