1. Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign Alex Apeagyei Prof Bill Buttlar Prof Barry Dempsey Development of Antioxidant Treatments for Asphalt Binders and Mixtures November 9, 2005

2. Outline of Presentation  Introduction  Research Approach  Experimental Design  Analysis of Results  Summary and Conclusions  Recommendations

3. Introduction: – Purpose of Study The goal was to develop Antioxidant (AOX) treatments … … to reduce oxidative aging in asphalt binders and mixtures

4. Problem Statement The problem of asphalt aging still exists despite the extensive use of antioxidants: Issues:  Sacrificial AOX, get consumed with time  Extensive degradation after 2-6 years  Possible environmental concerns

5. Experimental Plan  Selection of AOXs:- Eight additives  Binder testing  RTFO, PAV  Dynamic Shear Rheometer (DSR) Test  Bending Beam Rheometer (BBR) Test  Mixture testing  Tests performed on most promising AOX system  Creep Compliance, Dynamic modulus, Tensile strength, DC(T) Fracture Energy, Moisture damage

6. List of AOXs evaluated  Irganox 1010  Vitamin E (Irganox E201)  Irgafos P-EPQ  Dilaurylthiodipropionate (DLTDP)  Furfural  Acryloid B-48N  Carbon Black (Raven 790)  Hydrated Lime

7. Evaluation of Aging  Aging Index (AI) used for evaluating aging  AI of binders based on SUPERPAVE Parameters  G*/Sin  at 64 ºC  G*Sin  at 25 ºC  AI of mixtures based on  Creep Compliance, E*, Tensile Strength, Fracture Energy

8. Evaluation of Binder Results  Comparison of binder AI after RTFO AOX-Modified Control

9. Aging Index: G*Sin  at 25 ºC after PAV S13 – DLTDP + Furfural + Catalyst S14 – Vitamin E + Furfural + catalyst S16 - Control

10. Effect of AOXs on G*Sin  after PAV Control

11. Effect of AOXs on Creep Stiffness after PAV Control

12. Effect of AOXs on m-value at after PAV Control

13. Effects of AOX on long-term binder aging Improvement 40% Improvement 20%

14. Selection of most promising AOX  S13 contains DLTDP/Furfural + catalyst  S13 is most preferred AOX treatment  Sample S13 will be labeled AOX-Modified  Asphalt concrete mixtures limited to S13

15. Asphalt Mixture Fabrication  Materials:  Limestone aggregates (9.5 mm Nom. Max)  PG 64-22 binder (Control)  AOX-Modified PG 64-22 binder  Mixture Aging  Short-term oven aging (135 ºC for 2 hours, STOA-2h)  Long-term oven aging (135 ºC for 8 hours, LTOA-8h)

16. Mixture Tests Performed  Creep Compliance  Dynamic Modulus E*  Indirect Tensile Strength  DC(T) Fracture Test (Wagoner et al. 2004)  Moisture Susceptibility

17. Creep Compliance master curve (T ref = -20 C)

18. Effect of aging on creep compliance

19. E* master curve (T ref = 20 ºC)

20. Effect of aging on dynamic modulus E*

21. DC(T) Fracture Testing Test Setup DC(T) Specimen

22. Effect of Aging on Fracture Energy

23. Moisture Susceptibility  To investigate the moisture damage potential of AOX-Modified Asphalt Mix  Tests performed  AASHTO T283 [Tensile Strength Ratio, TSR]  DC(T ) [Fracture Energy Ratio, FER]  Aggregates used:  Limestone

24. Limestone Results Summary

25. Limestone mixtures: Visual rating

26. Conclusion The AOX treatments evaluated during this study appear to cause significant reduction in age-hardening of the PG 64-22 asphalt used

27. Recommendations  Evaluate AOXs using different asphalt sources  Full-scale production of the AOX-Modified  Construction of Full-scale pavement sections  Accelerated testing  Long-term performance evaluation

28. Acknowledgements  Research conducted at ATREL and was supported by the Center of Excellence for Airport Technology funded by the FAA  Special thanks to:  Prof Barry Dempsey – Director of Research  Prof Bill Buttlar – Advisor

29. End of Presentation Thank You!