Investigation on Preparation Method of SBS-Modified Asphalt Based on MSCR, LAS, and Fluorescence Microscopy

The preparation method of SBS-modified asphalt has a direct effect on its overall performance. Currently, the optimal process is usually determined by conventional performance properties, such as softening point, ductility, and penetration, which may deviate from practical field performance. This study aims to investigate the influence of different preparation methods on the performance and microstructure of SBS-modified asphalt based on fluorescence microscopy testing, the multiple stress creep recovery (MSCR) test, the linear amplitude sweep (LAS) test, as well as Burgers model fitting. SBS-modified asphalt was prepared with different shear rates, shear temperatures, shear times, development time, and sulfur addition. The results show that the optimal process for preparing SBS-modified asphalt is 2 h of shearing at 180 °C and 4000 r/min, followed by sulfurization and 6 h of development. The performance of SBS-modified asphalt is most notably influenced by sulfurization, which forms C–S bonds to make the polymer network stronger, thereby improving the high-temperature performance as well as the fatigue resistance. However, due to high-temperature sensitivity, C–S bonds may break during development, leading to weakened performance. The performance of SBS-modified asphalt without sulfur addition shows a monotonically increasing trend with the extension of development time.