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Asphalt binder is susceptible to aging from heat, air and sunlight exposure during service, leading to pavement distresses. This study aimed to improve the aging resistance of asphalt using zinc oxide-silicate (ZOS) composites. ZOS containing 2–8 wt% ZnO were synthesized via a one-step sol-gel method and incorporated into an unmodified 70/100 penetration grade asphalt binder. The rheological properties and aging characteristics were evaluated before and after rolling thin film oven and pressure aging vessel protocols. Dynamic shear rheometry showed increased complex modulus and decreased phase angle for ZOS-modified binders, indicating improved rutting resistance. Aging indices revealed the 6% ZOS composite had the least susceptibility to oxidative aging. FTIR analysis confirmed the formation of carbonyl and sulfoxide functional groups during aging, which were mitigated by ZOS addition. Scanning electron microscopy visualized nano-scaled ZnO particles dispersed within the silica matrix and asphalt binder. The ZOS composites delayed the aging rate through physicochemical interactions between ZnO and the asphalt medium. An optimum ZOS dosage of 4–6% was found to enhance the anti-aging properties. The renewable silica-supported ZnO composites show potential as cost-effective modifiers for improving asphalt durability.
Zhu et al. (Tue,) studied this question.