Improvement of short-term aging resistance of styrene-butadiene rubber modified asphalt by Sasobit and epoxidized soybean oil

Abstract Styrene-butadiene rubber modified asphalt (SBRMA) possesses the excellent low-temperature performance. Nevertheless, SBR copolymer is vulnerable to being decomposed when exposed to high-temperature and oxygen-rich environment during asphalt mixture mixing and compaction processes, which seriously compromises the improving effects of styrene-butadiene rubber (SBR) on thermal cracking resistance of asphalt binder. Therefore, reducing preparation temperatures of SBRMA mixture is a preferable way which can effectively enhance the performance of short-term aged SBRMA. In this research, in order to reduce the temperature during SBRMA mixture fabrication, three additives including Sasobit, epoxidized soybean oil (ESO) and Sasobit/ESO composite were chosen, and the effects of additives on physical, rheological properties of SBRMA, the chemical interactions between SBRMA and additives and their mixture preparation temperatures were evaluated. In addition, the effects of reduced short-term aging temperature by additives on performance of SBRMA and its mixture were investigated through physical, rheological, morphological and mechanical analyses. The results indicate that compared with Sasobit and ESO, Sasobit/ESO composite not only shows the better lowering effect on mixture preparation temperatures, but also can compensate for the adverse effects when Sasobit or ESO is added separately and enhance the high- and low-temperature performance of SBRMA concurrently. The reduced short-term aging temperature by Sasobit/ESO is beneficial to mitigating the adverse impacts of aging on performance of SBRMA. Moreover, adding Sasobit/ESO composite can enhance the thermal cracking resistance of SBRMA mixture.