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Publication Number: FHWA-RD-02-042
Date: October 2000

Modified Asphalt Binders in Mixtures - Topical Report: Permanent Deformation Using A Mixture With Diabase Aggregate

National Cooperative Highway Research Program
(NCHRP) Project 90-07

View Table of Contents

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

Walaa S. Mogawer, PhD, P.E.
Civil and Environmental Engineering Department
University of Massachusetts Dartmouth
North Dartmouth, MA 02747
TELEPHONE: (508) 999-8468
FAX: (508) 999-8964

FOREWORD

This report documents the effects of polymer-modified asphalt binders on the rutting resistance of a mixture with diabase 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 to 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. For the materials tested in this study, good correlations between asphalt binder properties and laboratory mixture rutting resistance were found, which indicate that the current Superpave asphalt binder specification and testing protocols are valid. Additional mixtures will be tested by FHWA to verify these findings. This report will be of interest to highway personnel who use polymer-modified asphalt binders and Superpave.

T. Paul Teng, P.E.
Director, Office of Infrastructure
Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

Technical Report Documentation Page

1. Report No.

FHWA-RD-02-042

2. Government Accession No. 3 Recipient's Catalog No.
4. Title and Subtitle

UNDERSTANDING THE PERFORMANCE OF MODIFIED ASPHALT BINDERS IN MIXTURES: PERMANENT DEFORMATION USING A MIXTURE WITH DIABASE AGGREGATE

5. Report Date

 

6. Performing Organization Code
7. Author(s)

Kevin D. Stuart and Walaa S. Mogawer

8. Performing Organization Report No.

 

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

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 - December 2001

14. Sponsoring Agency Code

 

15. Supplementary Notes

FHWA Contact: Kevin D. Stuart, HRDI-11

16. Abstract

The objective of this study was to determine if the Superpave high-temperature properties of polymer-modified asphalt binders correlate to asphalt mixture rutting resistance. An emphasis was placed on evaluating the rutting resistances of mixtures containing polymer-modified asphalt binders with identical (or close) performance grades, but varied polymer chemistries. This would indicate what types of modification provide properties that are, or are not, correctly captured by the current Superpave asphalt binder specification. Eleven asphalt binders were obtained for this study: two unmodified asphalt binders, an air-blown asphalt binder, and eight polymer-modified asphalt binders. Five binders used in a prior study were also tested.

Asphalt binder properties were measured by a dynamic shear rheometer. Mixture rutting resistance was measured by: (1) G* and G*/sin(delta) from the Superpave Shear Tester (SST) frequency sweep at constant height, (2) cumulative permanent shear strain from the SST repeated shear at constant height (RSCH), (3) French Pavement Rutting Tester (French PRT), and (4) the Hamburg Wheel-Tracking Device. Cumulative permanent shear strain and the French PRT were the primary tests because they were specifically developed to measure rutting resistance.

The high-temperature properties of the 11 asphalt binders had a high correlation to mixture rutting resistance as measured by the cumulative permanent shear strains. A weak correlation was found using the French PRT. Both correlations were high when analyzing the data from all 16 asphalt binders. A change in high-temperature PG from 70 to 76 significantly increased rutting resistance based on both tests.

The main objective of this study was to determine which asphalt binders provide high-temperature properties that do not agree with mixture rutting resistance. In general, the number of discrepancies was low. It is recommended that the asphalt binders be tested using other aggregate types or gradations.

17. Key Words

Superpave, asphalt binder specification, permanent deformation, Superpave Shear Tester, SST, French Pavement Rutting Tester, Hamburg Wheel-Tracking Device, 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.

19. Security Classification
(of this report)

Unclassified

20. Security Classification
(of this page)

Unclassified

21. No. of Pages

57

22. Price
Form DOT F 1700.7 Reproduction of completed page authorized

TABLE OF CONTENTS

Section

1. Background

2. Objective

3. Materials

4. Tests

5. Evaluation Using G* and G*/sind

6. Cumulative Permanent Shear Strain

7. French PRT

8. Hamburg WTD

9. Evaluation of Data Without Statistical Analysis

10. Comparison of Mixture Tests

11. Conclusions

a. Conclusions Provided by the 11 Mixtures
b. Conclusions Provided by All Mixtures

12. Recommendations

13. References

LIST OF FIGURES

Figure No.

1. G* using new aggregate blend vs. G* using original aggregate blend

2. Aggregate gradation

3. Diagram of SST chamber

4. Superpave Shear Tester

5. G*/sind of the asphalt mixture vs. G*/sind of the asphalt binder using the 11 asphalt binders

6. G*/sind of the asphalt mixture vs. G*/sind of the asphalt binder using all 16 asphalt binders

7. G*/sind of the asphalt mixture at 50°C vs. high-temperature PG using the 11 asphalt binders

8. G*/sind of the asphalt mixture at 50°C vs. high-temperature PG using all 16 asphalt binders

9. G*/sind of the asphalt mixture at 2.0 Hz vs. G*/sind of the asphalt binder at 2.0 rad/s using the 11 asphalt binders

10. G*/sind of the asphalt mixture at 2.0 Hz vs. G*/sind of the asphalt binder at 2.0 rad/s using all 16 asphalt binders

11. Cumulative permanent shear strain vs. G*/sind of the asphalt binder at 10.0 rad/s using the 11 asphalt binders

12. Log cumulative permanent shear strain vs. log G*/sind of the asphalt binder at 10.0 rad/s using all 16 asphalt binders

13. Cumulative permanent shear strain at 50°C vs. high-temperature PG using the 11 asphalt binders

14. Log cumulative permanent shear strain at 50°C vs. log high-temperature PG using all 16 asphalt binders

15. Log cumulative permanent shear strain vs. log G*/sind of the asphalt binder at 0.125 rad/s using the 11 asphalt binders

16. Log cumulative permanent shear strain vs. log G*/sind of the asphalt binder at 0.125 rad/s using all 16 asphalt binders

17. French Pavement Rutting Tester

18. French PRT wheel and slab

19. French PRT rut depth vs. G*/sind of the asphalt binder at 0.9 rad/s using the 11 asphalt binders

20. Log French PRT rut depth vs. log G*/sind of the asphalt binder at 0.9 rad/s using the 11 asphalt binders

21. French PRT rut depth vs. G*/sind of the asphalt binder at 0.9 rad/s using all asphalt binders

22. Log French PRT rut depth vs. log G*/sind of the asphalt binder at 0.9 rad/s using all asphalt binders

23. French PRT rut depth at 70°C vs. high-temperature PG using the 11 asphalt binders

24. French PRT rut depth at 70°C vs. high-temperature PG using all asphalt binders

25. Hamburg Wheel-Tracking Device without water

26. Rut depth vs. wheel passes from the Hamburg WTD at 58°C

27. RSCH cumulative permanent shear strain at 50°C vs. French PRT rut depth at 70°C for the 11 mixtures

28. Log RSCH cumulative permanent shear strain at 50°C vs. log French PRT rut depth at 70°C for all mixtures

29. Log RSCH cumulative permanent shear strain vs. log FSCH G*/sind for all mixtures

LIST OF TABLES

Table No.

1. Comparison of SST properties provided by the original and new aggregate blends

2. Descriptions of the asphalt binders

3. Performance grade (PG) for each asphalt binder

4. Aggregate properties for the diabase

5. Volumetric properties of the mixtures

6. G*/sind's of all binders and mixtures with the materials listed from the highest to lowest mixture G*/sind

7. G*/sind's of the 11 binders and mixtures with the materials listed from the highest to lowest mixture G*/sind

8. Replicate data for G*/sind at 50oC

9. G*/sind's of the asphalt binders vs. cumulative permanent shear strain

10. Statistical rankings for the 11 asphalt mixtures based on cumulative permanent shear strain

11. Replicate data for the cumulative permanent shear strains

12. G*/sind's of the asphalt binders at 10.0, 2.0, and 0.125 rad/s with the asphalt binders listed from highest to lowest G*/sind using 0.125 rad/s

13. G*/sind's of the asphalt binders vs. the French PRT with the materials listed from the lowest to highest rut depth at 6,000 wheel passes

14. Replicate data for the French PRT

15. G*/sind's of the binders vs. the creep slopes from the Hamburg WTD with the materials listed from highest to lowest slope (highest to lowest resistance to rutting)

16. Replicate data for the Hamburg WTD

17. Rankings by test type with the material having the most resistance to rutting listed at the top

18. Numerical rankings by test type where No. 1 has the most resistance to rutting according to the test and No. 11 has the least resistance to rutting

19. Coefficients of determination, r2, using the data from the 11 mixtures

20. Coefficients of determination, r2, using the data from all mixtures

 

PERSONNEL

John S. Youtcheff and Kevin D. Stuart, FHWA, Turner-Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101-2296

Walaa S. Mogawer, Civil and Environmental Engineering Department, University of Massachusetts Dartmouth, North Dartmouth, MA 02747

Naga Shashidhar, Susan Needham, Scott Parobeck, and Frank Davis, SaLUT, Turner-Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101-2296

Aroon Shenoy, Senior Research Fellow, FHWA, Turner-Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101-2296

SI* (Modern Metric) Conversion Factors

 

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