Development of Antioxidant Treatments for Asphalt Binders and Mixtures

1. Development of Antioxidant Treatments for Asphalt Binders and Mixtures Alex Apeagyei Prof Bill Buttlar Prof Barry Dempsey 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*/Sind at 64 ºC • G*Sind 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 Control AOX-Modified

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

10. Effect of AOXs on G*Sind 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 20% Improvement 40%

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 (Tref = -20 C)

18. Effect of aging on creep compliance

19. E* master curve (Tref = 20 ºC)

20. Effect of aging on dynamic modulus E*

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

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!