Investigation on the performance effects of hydroxyl-terminated polybutadiene polyurethane modified asphalt after short-term and long-term aging

Polyurethane can significantly improve the asphalt’s high-temperature performance, mechanical properties, and water stability. However, aging is an unavoidable process for asphalt binders during construction. This study employed hydroxyl-terminated polybutadiene (HTPB) polyurethane as a polymer modifier to examine the impact of aging on the microstructure and rheological properties of polyurethane-modified asphalt (PUMA). Fluorescence microscopy and Fourier transform infrared spectroscopy were used to analyze the microstructural changes before and after aging. In addition, the high- and low-temperature performance, fatigue resistance, and adhesion properties of HTPB-PUMA were systematically evaluated and compared with those of base asphalt and styrene-butadiene-styrene (SBS) modified asphalt. Results indicated that the aging behavior of HTPB-PUMA was similar to that of SBS-modified asphalt, characterized by asphalt phase aging and polymer phase degradation. The incorporation of polyurethane mitigated the negative effects of aging on high-temperature properties, low-temperature relaxation, fatigue resistance, and pull-off strength, thereby improving the overall aging resistance of asphalt. This study provides scientific guidance for advancing the anti-aging performance of PUMA in pavement applications.