Application of oil shale waste for anti-aging improvement of asphalt mortar through component regulation

Oil shale waste (OSW) shows great potential as a fine aggregate in asphalt pavements due to its porous structure and oil-retaining capacity. However, its role in regulating asphalt components has received limited attention. This study investigated the performance enhancement and component regulation mechanism of OSW in asphalt mortar using dynamic shear rheometer (DSR) tests, Fourier-transform infrared (FTIR) spectroscopy, four-component analysis, and molecular dynamics (MD) simulations. Compared with basalt asphalt mortar (BS-AM), OSW asphalt mortar (OSW-AM) exhibited over 20% higher complex shear modulus and over 30% higher creep recovery rate. After 720 h of laboratory aging, the sulfoxide index of OSW-AM was 14.17% lower than that of BS-AM, while its aromatic content remained nearly unchanged. MD simulations (300 ps) showed decreases of 2.44% and 1.35% in saturates and aromatics, respectively, indicating directional migration of light components and gradual release of oil-retaining substances into the aged asphalt, thereby mitigating aging. These results demonstrate that OSW functions as an oil-storage fine aggregate capable of regulating and releasing asphalt components, providing enhanced anti-aging performance through directional migration of light components.