Rutting-Resistance Investigation of Alternative Polymerized Asphalt Mixtures

Polymers have been incorporated into asphalt as a way to mitigate permanent deformation at high performance temperatures for many years. There are several types of polymers used in asphalt binders to improve the rheological and engineering properties of asphalt mixtures, including styrene butadiene styrene (SBS), ground tire rubber, styrene butadiene rubber, ethylene vinyl acetate, and polyethylene. SBS is the most popular polymer used in high-traffic pavement compared with other polymer modifiers. However, recent studies have shown that mixtures containing some other modifiers are cost-effective and perform as well as or better than SBS-modified binders in some cases. The experimental design in this study included one base binder, PG 64-22; two aggregate sources; SBS and five other modifiers; and three antistripping additives (ASAs). Asphalt pavement analyzer (APA) and Hamburg wheel tracker (HWT) were used to investigate the rut resistances of these alternative modified-asphalt mixtures. It was found that the APA and HWT rut depths of all alternative modified mixtures met the requirements of rut resistance, and these values were typically located in the range of 1-3mm regardless of polymer type, ASA type, and aggregate source. The ASAs used in this study were effective and did not display significant differences in rut-resistance values from various polymerized mixtures. Simple logarithmic formulas for HWT rut depth during the loading process and the normal distributions of rut depths were developed in this study.