Rheological Properties of Polyurethane-Modified Asphalt and Its Effect on the Performance of Porous Asphalt Mixes

To address the growing demand for transportation infrastructure, the development of high-performance modified asphalt is significant for rapid pavement construction. This study aims to evaluate the properties of polyether-polyurethane-prepolymer–modified asphalt and verify its road performance. By adjusting the polyether-polyurethane content (0% to 12%), its fundamental properties were systematically tested, and its rheological characteristics were analyzed using dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. Subsequently, Fourier transform infrared spectroscopy (FTIR) was employed to investigate its microstructural characteristics. In addition, asphalt mixtures were prepared using PAC-13 aggregate gradation, and their pavement performance was evaluated. The results indicate that adding 8% polyether-polyurethane significantly enhances the mechanical properties and high-temperature stability of the modified asphalt. Temperature sweep and multiple stress creep recovery (MSCR) tests show that its high-temperature performance surpasses that of base asphalt and approaches that of styrene-butadiene-styrene (SBS)-modified asphalt. At intermediate temperatures, the fatigue life of polyurethane-modified asphalt is significantly improved and exceeds that of SBS-modified asphalt. Regarding low-temperature performance, BBR test results reveal a marked improvement compared to base asphalt, although the polyurethane-modified asphalt remains slightly inferior to SBS-modified asphalt. FTIR results demonstrate the formation of new urethane (─ NHCOO─ ) groups in the modified asphalt, indicating chemical reactions that strengthen the cross-linked network structure and enhance aging resistance. Pavement performance tests confirm that polyurethane-modified asphalt mixtures meet the construction requirements for high-temperature performance, low-temperature performance, and moisture stability. Furthermore, their high- and low-temperature performance surpasses that of base asphalt mixtures, although the moisture stability is slightly lower than that of SBS-modified asphalt mixtures. In summary, this study provides theoretical insights and practical references for the application and promotion of polyurethane-modified asphalt in road engineering.