Aging Resistance of Asphalt Mixtures Modified by Composites of Organic Intercalated Layered Double Hydroxides and Antioxidants

To enhance the thermal oxygen aging and ultraviolet (UV) aging resistance of asphalt mixture, cinnamic acid–modified layered double hydroxyl composite metal hydroxides (LDHs) and para-aminobenzoic acid–modified LDHs (CA-LDHs and PABA-LDHs) were prepared to improve the compatibility between LDHs and asphalt. The road performance and aging resistance of the modified asphalt mixture were tested to characterize the composite modification effects of the organic LDHs and antioxidants, and the mechanisms of LDHs and antioxidants in the asphalt mixture were investigated using the gel permeation chromatography (GPC) test. Results show that antioxidants, LDHs, CA-LDHs, and PABA-LDHs can boost the aging resistance of base asphalt mixture and styrene-butadiene-styrene (SBS)–modified asphalt mixture. CA-LDHs provide the most significant improvement, followed by PABA-LDHs, LDHs, and antioxidants in descending order of effectiveness. Additionally, the use of organic LDHs in combination with composite antioxidants further enhanced the durability of asphalt mixtures compared to using a single modifier alone. Organic LDHs and antioxidants exhibit a synergistic effect, improving the resistance of asphalt mixture to thermal oxidative aging and UV aging.