The utilization of oil-rich reclaimed asphalt pavement fine aggregate (O-RAP), characterized by its high asphalt content, which has inherent compatibility with the high asphalt demand of stress-absorbing layer (SAL) mixtures, enables significant recycling rates, thereby promoting resource efficiency and a promising pathway for sustainable infrastructure development. This study provides a comprehensive evaluation of the rheological properties of recycled asphalt binder through dynamic shear rheometer and bending beam rheometer tests. Furthermore, the pavement performance of SAL mixtures was systematically assessed via fatigue testing, moisture susceptibility evaluation, rutting resistance analysis, and overlay testing. The results indicate that increasing the O-RAP content enhances the complex shear modulus while reducing the phase angle, suggesting improved stiffness but reduced flexibility of the binder. In SAL mixtures, higher O-RAP content was associated with decreased fatigue life, moisture stability, and low-temperature cracking resistance, yet it contributed to improved resistance to reflective cracking and high-temperature rutting. Pearson correlation analysis further revealed that the fatigue life of the binder exhibits a strong positive correlation with creep rate and significant negative correlations with creep stiffness modulus, high-temperature stability, and reflective cracking resistance. These findings underscore the viability of high-content O-RAP incorporation in SAL mixtures as a technically sound and environmentally sustainable strategy for low-carbon pavement construction, offering significant reductions in virgin material consumption and associated carbon emissions.

Surface modification processes significantly influence the aggregate characteristics of steel slag and the road performance of asphalt mixtures. Therefore, this study employs four different substances to conduct surface modification treatment on aged steel slag with particle size ranges of 4.75–9.5 mm and 9.5–13.2 mm to determine the optimal surface modification process through macroscopic and microscopic analytical methods. Ultimately, a comparative analysis is performed on the pavement performance of asphalt mixtures incorporating aged steel slag and modified aged steel slag at different volume replacement ratios. Experimental results demonstrate that Epoxy Acrylate-Modified Organosilicon Resin (EAOR) significantly improved the aggregate properties of Aged Steel Slag (ASS), making it a viable alternative to natural stone; under identical conditions, the volume stability of modified aged steel slag (EAOR-ASS) was slightly superior to that of ASS, while the differences in high-temperature stability and low-temperature cracking resistance of the corresponding asphalt mixtures were minimal. Surface modification of ASS with EAOR significantly enhanced the water damage resistance of the asphalt mixture under freeze–thaw cycle conditions, thereby improving the utilization rate of steel slag. Both an increased volume replacement ratio of steel slag and surface modification with EAOR contributed to improved resistance to elastic deformation of the asphalt mixture.