Excellent low temperature performance for modified asphalt by finely dispersed sidewall tire rubber

Abstract

Low temperature performance of rubber asphalt in cold regions still has challenges for facing cracking. In this study, the modified asphalt by finely dispersed degraded sidewall tire rubber (STR) was prepared to study its low temperature performance by bending beam rheometer, differential scanning calorimetry, Fraass brittleness temperature and ductility. Results showed that low test temperature and Fraass brittleness temperature of STR-modified asphalt could be down to −24.0 °C, both of which were better than that of current crumb tire rubber modified asphalt. The ductility at temperature of 5 °C was 22.3 cm, which was higher than those of other tire section rubber modified asphalt, such as tread tire rubber modified asphalt (TTRMA, 19.8 cm) and bead tire rubber-modified asphalt (BTRMA, 15.6 cm). This was owing to that STR-modified asphalt had low glass transition temperature (Tg) of −33.1 °C, which was lower than those of TTRMA (−32.9 °C) and BTRMA (−31.2 °C). Modification mechanism proposed that flexible butadiene rubber (Tg of −110.0 °C) in STR strongly promoted the relaxation of rubber molecular segments through molecular orientation and conformation switching when suffering stress concentration. Accordingly, the STR-modified asphalt had excellent low temperature performance, and could be practically used for flexible pavement in cold region.