Macroscopic mechanical degradation of asphalt pavements induced by hydrodynamic scouring in hot-humid regions

Moisture damage is a major cause of early distress in asphalt pavements in hot-humid regions. This study investigated the mechanical performance evolution of SMA-13 and PA-13 under hydrodynamic scouring using five indicators: mass loss, indirect tensile strength (ITS), uniaxial compressive strength (UCS), uniaxial penetration strength (UPS), and dynamic modulus. An evaluation model based on the analytic hierarchy process (AHP) was developed to identify optimal indicators. Results showed that PA-13 experienced more severe deterioration, with damage progressing from interfacial debonding to skeleton degradation. UPS was the most sensitive indicator of early damage. For SMA-13, deterioration initially involved low-temperature modulus reduction, followed by skeleton-controlled degradation. AHP results identified ITS and mass loss as the primary indicators for PA-13, while ITS and dynamic modulus ratio (DMR) were more suitable for SMA-13. These findings provide a basis for differentiated moisture damage evaluation and asphalt pavement design in hot-humid regions.