Innovative reaction-rejuvenation of aged SBS modified asphalt binder: From physico-rheological behavior to rejuvenation mechanism

Recycling waste SBS-modified asphalt (SBSMA) is crucial, yet conventional oil-based rejuvenators severely compromise its high-temperature deformation resistance, limiting its reuse in pavements. The study proposed a new reaction-rejuvenation approach through combining reactive chemicals of 1,4-butanediol diglycidyl ether (BUDGE) and pre-polymerized polyurethane (Pre-PU) with physical rejuvenator of heat transfer oil (HTO) residue to reach the performance optimization of reaction-rejuvenated SBSMA (RRSBSMA) binder. Comprehensive evaluation of the rejuvenated binder's physical and rheological properties demonstrates that this method successfully balances performance. The reactive chemicals effectively mitigate the decline in high-temperature stability, while the HTO residue appropriately improves workability. Mechanism analysis revealed that the chemicals form a rigid, gel-like molecular structure. This network maintains a high modulus, providing excellent rutting resistance—confirmed by complex modulus and accumulated strain results—while simultaneously absorbing the softening HTO residue. This breakthrough enables the high-performance recycling of waste SBSMA, advancing the development of more durable and sustainable asphalt pavements.