Retarding aging of asphalt binders using antioxidant additives and copolymers

Abstract

The rheological properties of asphalt binders change with aging. Aging is accelerated at elevated temperatures due to binder oxidation, leading to fatigue cracking and eventually pavement failure under heavy and repeated traffic loading. This study examined the effect of various antioxidant additives and copolymers with antioxidant agents on retarding the aging of asphalt binders. The performance of antioxidants was evaluated at the binder and mastic levels. Two unmodified binders were tested and fine asphalt mixtures made with these binders and three different aggregates were prepared and evaluated. Fatigue characteristics of asphalt binders and fine portion of asphalt mixtures (FAM) were determined before and after aging and an aging index was defined to evaluate the effect of antioxidants and copolymers on aging. The results showed that certain antioxidants and copolymers such as Redicote AP, Solprene and Calprene may retard the aging and improve the rheological properties of the asphalt binders. In addition, the results of FAM testing confirmed the favourable effect of certain antioxidants on improving the resistance to fatigue. In addition, the type of aggregate was found to influence the rate of aging of asphalt mixtures.

Keywords:

• Binder aging
• antioxidants
• copolymers
• FAM
• gabbro
• limestone

Acknowledgment

This paper was made possible by the NPRP grant (NPRP 6-773-2-320) from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.

Additional information

Funding

This work was supported by Qatar National Research Fund [grant number NPRP 6-773-2-320].