Effect of Bonding Characteristics on Rutting Resistance and Moisture Susceptibility of Rubberized Reclaimed Asphalt Pavement

Asphalt pavements incorporating recycled and sustainable materials have become a widely adopted strategy in road construction, particularly with the use of reclaimed asphalt pavement (RAP) and crumb rubber (CR) derived from waste tires. However, the adhesion and cohesion characteristics of rubberized RAP mixtures remain insufficiently understood. This study investigates how interfacial bonding affects the rutting resistance and moisture susceptibility of rubberized RAP asphalt mixtures. Two RAP sources with different aging levels and two CR particle sizes (250 μm and 380 μm) were evaluated. Binder bond strength (BBS) tests showed that pull-off strength increased with the use of smaller CR particles and more highly aged RAP, while rotational viscosity and penetration tests confirmed the corresponding increase in binder stiffness. Hamburg wheel track (HWT) tests with high-temperature viscoplastic deformation analysis demonstrated improved rutting resistance in the tested mixtures. Furthermore, boiling tests supported by image analysis revealed reductions in stripping ratios, indicating enhanced moisture resistance. ANOVA results (p < 0.05) confirmed that CR content had a significant effect on bonding characteristics, whereas RAP aging and CR particle size jointly influenced rutting performance. Overall, mixtures incorporating 10% CR and 25% RAP achieved the best balance between adhesion, cohesion, and durability. These findings provide a quantitative understanding of how interfacial bonding governs the mechanical performance and moisture resistance of rubberized RAP mixtures.