Improving Effects of Warm-Mix Additive Sasobit on Performance of Short-Term Aged SBR Modified Asphalt

Styrene-butadiene rubber (SBR) modified asphalt (SBRMA) can exhibit a good low-temperature performance. However, exposure to high-temperature and oxygen-containing environment can easily lead to decomposition of SBR modifier during the pavement construction process, which seriously compromises the modifying effects endowed by SBR modifier. To mitigate the negative influence of short-term aging on the performance of SBRMA, the warm-mix additive Sasobit was added into SBRMA due to its role in reducing mixing temperatures of asphalt mixture. In this paper, the mixing temperature of asphalt mixture was determined based on equal viscosity principle and set as short-term aging temperature of corresponding asphalt binder. The effect of Sasobit on the short-term aging temperature of the asphalt binder was further evaluated. In addition, the effects of Sasobit on un-aged and short-term aged SBRMA were investigated by physical, rheological, infrared spectrum, fluorescence microscopy and gel permeation chromatography tests. The results indicated the addition of Sasobit can effectively reduce the short-term temperature of SBRMA by 14 oC through its effect of reducing viscosity. And the addition of Sasobit can improve the high-temperature stability of SBRMA but decrease its low-temperature ductility. The reduced short-term temperature due to adding Sasobit can mitigate the negative influence of short-term aging on SBRMA and SBR modifiers through physical and rheological aging indexes, chemical functional group, fluorescent images and polymer molecular weight evaluation.