Performance enhancement of SBS modified asphalt using polyurethane precursor-based reactive modifiers

Polymer modifiers represented by SBS is widely used to enhance the mechanical performance and durability of asphalt pavement. However, complex environments and growing vehicle loads have placed higher requirements on the long-term performance of SBS modified asphalt. In this study, a polyurethane precursor-based reactive modifier (PRM) was incorporated into SBS modified asphalt, and the resulting SBS-PRM composite modified asphalt exhibited better pavement performance compared to conventional SBS-modified asphalt. The basic properties were measured to verify that the PRM composite modified asphalt satisfy the requirements in specification. Test procedures of dynamic shear rheometer and bending beam rheometer, were conducted to evaluate the rheological performance of modified asphalt binders. Experimental tests indicated that the high-temperature performance grades (PG) of SBS modified asphalt are enhanced due to the addition of PRM. The stress sensitivity of asphalt samples is reduced resulted in the excellent permanent deformation resistance. And the Bending beam rheometer (BBR) tests revealed that the addition of PRM did not significantly change the low-temperature PG of SBS modified asphalt, although a moderate increase in creep stiffness was observed. Besides, the SBS-PRM composite modified asphalt exhibit better fatigue resistance based on linear amplitude sweep (LAS) tests. The presence and interaction mechanisms of different modifiers were investigated using fluorescence microscopy and Fourier transform infrared spectroscopy. Furthermore, correlation analysis was employed to elucidate the relationship between chemical modification and the enhancement of asphalt performance. The findings of this study provide valuable insights for the practical implementation of PRM modifiers in asphalt pavement engineering applications.