Improving Bitumen Performance and Aging Resistance: Comparative Study of Common Antiaging Additives and Zinc Oxide and Expanded Vermiculite Composite

Abstract Enhancing the durability of bituminous pavements requires effective antiaging additives for bitumen. However, the unclear differences in microstructure and performance enhancement among various additives hinder their optimization and application. This study evaluates the effects of four antiaging additives on bitumen performance and aging resistance: antioxidant (AO), ultraviolet absorber (UVA), their combination (UVA+AO), and a novel zinc oxide/expanded vermiculite composite (ZnO/EV). Results show that unlike UVA and AO, which undergo structural changes in bitumen, ZnO/EV maintains structural stability and demonstrates superior ultraviolet absorption (about 20% higher than UVA) and thermal stability. These superior intrinsic properties translate into enhanced performance for ZnO/EV modified bitumen. ZnO/EV significantly increases bitumen stiffness and elastic response in the unaged state, improving resistance to permanent deformation while maintaining excellent low-temperature flexibility. Critically, ZnO/EV provides consistently superior short- and long-term aging resistance across all tested conditions, markedly reducing aging-induced changes (e.g., softening point increment, viscosity aging index). In contrast, the common additives show limitations: UVA can impair short-term aging resistance, AO provides only moderate improvement, and the UVA+AO compound fails to synergize effectively, underperforming ZnO/EV. This study conclusively demonstrates that ZnO/EV significantly outperforms conventional antiaging additives in both enhancing bitumen’s key performance properties and providing robust, multicondition aging resistance, highlighting its strong potential for durable pavement applications.