Synergistic antioxidant systems in rejuvenated asphalt: enhanced rheological and fatigue properties during re-ageing

Rejuvenated asphalt is more susceptible to oxidative aging than virgin asphalt, resulting in rapid deterioration of rheological properties during service. Incorporating antioxidants is an effective strategy to mitigate this re-aging behavior. This study systematically evaluates the effects of the phenolic antioxidant 1010, phosphite antioxidant 168, and their composite system on the rheological properties, fatigue performance, and aging resistance of rejuvenated asphalt across multiple aging stages. The results indicate that antioxidant 1010, as a primary antioxidant, suppresses the initial oxidation rate by scavenging peroxy radicals, while antioxidant 168 functions as a secondary antioxidant by inhibiting the degenerate branching of the oxidative reactions, thereby enhancing rheological stability. The synergistic combination of 1010 and 168 establishes a multi-phase protective system that significantly outperforms single-antioxidant formulations. This system effectively reduces the epoxy ring-opening rate of ESO and suppresses the oxidation of light components in rejuvenated asphalt. Overall, the composite system (1010 + 168) provides balanced and durable inhibition of reaction rate, maintaining rheological stability and fatigue performance even after prolonged aging. This study offers a promising anti-aging strategy for extending the service life of rejuvenated asphalt, thereby promoting resource recycling and contributing to environmentally sustainable pavement engineering. The synergistic combination of 1010 and 168 establishes a multi-phase protective system that significantly outperforms single-antioxidant formulations. This system effectively reduces the epoxy ring-opening rate of ESO and suppresses the oxidation of light components in rejuvenated asphalt. Overall, the composite system (1010 + 168) provides balanced and durable inhibition of reaction rate, maintaining rheological stability and fatigue performance even after prolonged ageing. This study offers a promising anti-ageing strategy for extending the service life of rejuvenated asphalt, thereby promoting resource recycling and contributing to environmentally sustainable pavement engineering.