Mitigating Moisture-Induced damage in porous asphalt via polyurethane prepolymer Modification: Performance investigation and void structure assessment

Porous asphalt (PA) is valued for its high water permeability and low noise characteristics, supporting its increasing use in pavement applications. However, its highly interconnected void structure facilitates moisture ingress, which accelerates moisture-induced deterioration and shorten service life. Improving the moisture durability of PA is therefore essential for maintaining its functional benefits, reducing premature maintenance, and promoting more resource-efficient pavement systems. To address this limitation, this study employs polyurethane prepolymer (PUP) as a chemically reactive modifier to enhance the moisture resistance of PA. First, a freeze–thaw splitting test was conducted to evaluate the overall moisture damage resistance of PUP-modified PA (PU-PA). Subsequently, the ability of PUP to preserve the cracking, raveling, and rutting resistance of PA after moisture damage was assessed using the semi-circular bending, Cantabro abrasion, and Hamburg wheel tracking tests, respectively. In addition, computed tomography (CT) scanning was performed to quantify moisture-induced evolution of the internal void structure in PU-PA. The results show that PUP modification mitigates moisture-related degradation in the mechanical properties of PA and better preserves void structure integrity after conditioning, indicating enhanced durability against moisture-induced deterioration.