Enhancement of mechanical and rheological properties of epoxy-recycled asphalt binders through SBS/CR composite modification

Using epoxy resins to recover the properties of aged binders offers an effective way to realise high-content recycling of reclaimed asphalt pavement (RAP), while its performance is expected to be further enhanced. When combining epoxy recycling technology with styrene-butadiene-styrene (SBS)/crumb rubber (CR) composite modified asphalt, the simultaneous recycling of both waste tires and aged binders can be achieved. This study aims to characterise the performance of epoxy-recycled asphalt (ERA) modified by SBS/CR with different aged binder contents, including tensile properties, low-temperature performance, thermal stability, fatigue resistance, and microscopic morphology. Additionally, its viscoelastic behaviours were analysed by constructing master curves using a novel Generalized Logistic Sigmoidal (GLS) model. The results indicate that the tensile properties and thermal stability of SBS/CR ERA with 80% aged binders, as well as the low-temperature performance and fatigue resistance of those with 60% aged binders, are superior to unmodified virgin epoxy asphalt. SBS/CR ERA displays great elastic deformability and reduced temperature susceptibility, with all phase angles below 45°, attributed to the strong network structures. Overall, SBS/CR modification provides a feasible solution for recycling high percentages of aged binders with enhanced mechanical and rheological properties. It will contribute to ‘epoxy recycling’ systems and sustainable pavements.