Friction–Adhesion Coupling Behavior of SBS-Modified Asphalt Pavement with Discontinuous Surface Texture

Pitting distress introduces discontinuous surface texture, thereby modifying the friction–adhesion coupling at the rubber–asphalt interface. This study systematically investigates the interfacial friction response of SBS-modified asphalt pavements with three pitting distribution patterns (sparse, medium, and dense) under varying sliding rates, temperatures, and cyclic loading using a custom-developed friction testing apparatus. The results reveal that adhesion-dominated friction is strongly dependent on both texture distribution and operating conditions. With increasing temperature, the dense pattern exhibits the most pronounced adhesion enhancement, with an average friction increase of 55.0%. The sparse pattern shows a continuous decreasing trend in the low-to-medium speed range, but exhibits a strengthening rebound at high speeds, demonstrating the most complex rate sensitivity. Under cyclic loading, among the three pitting patterns tested, the dense pattern exhibits the best friction retention, with an average friction reduction of only 6.2% after 30 cycles, compared to 9.5% for the sparse pattern and 10.8% for the medium pattern. Three-dimensional topography indicates that the medium pattern exhibits a continuous and relatively uniform wavy roughness, while the dense pattern transforms into a high-frequency serrated morphology. However, the wear in both patterns is dominated by homogenized micro-grooves, without the formation of local deep pits or sharp undulations, which favors the maintenance of stable skid resistance under the laboratory cyclic loading conditions tested in this study. Furthermore, a unified regression model with distribution dummy variables and interaction terms (R2 = 0.826; cross-validated Q2 = 0.646) quantifies the synergistic effect of pitting density and temperature, with the temperature sensitivity increasing six-fold from the sparse to the dense pattern (0.011 to 0.071 N/°C).