Study on the modification effects and mechanisms of organic–inorganic composite anti-aging agents on asphalt across multiple scales

Abstract To optimize the modifying effect of inorganic additives by using organic modifier, this study selected layered double hydroxides (LDHs) and ultraviolet (UV) absorbers as anti-aging agents to prepare modified asphalt. The anti-aging performance of modified asphalt was evaluated using a weathering tester. The influence of the composite modification effects of organic–inorganic modifiers on the pavement performance of asphalt binders was investigated through conventional tests. Dynamic shear rheometer tests were conducted to examine the performance grade classification of the composite anti-aging-modified asphalt. Fourier transform infrared spectroscopy was employed to analyze the variations in functional group composition of the composite-modified asphalt. Furthermore, molecular dynamics simulations were utilized to elucidate the changes of composite-modified asphalt at the molecular level under UV aging. The results indicate that the incorporation of UV absorbers significantly mitigates the adverse effects of LDHs on the physical properties of asphalt, while their synergistic modification enhances the anti-aging performance of the modified asphalt. Due to the addition of UV absorbers, the solubility difference between the composite modifier and asphalt improves compared to that of LDHs alone. Moreover, as the proportion of UV absorbers increases, the solubility difference gradually decreases, enhancing the thermal stability of the asphalt system.