Curing behavior and performance evolution of epoxy asphalt reclaimed binder and mixture

To clarify how curing-induced crosslinking in epoxy asphalt reclaimed systems affects mixture compaction quality, we investigated curing behavior at both the binder and mixture scales using epoxy asphalt reclaimed binder (REAB) and epoxy asphalt reclaimed mixture (REAM), respectively. Tensile, Brookfield viscosity, dynamic shear rheometer (DSR), bending beam rheometer (BBR), and fluorescence microscopy tests were conducted to characterize the phase evolution and high- and low-temperature rheological behavior of REAB. The compaction characteristics and mechanical properties of REAM at different curing stages were evaluated based on air-void content and indirect tensile strength. The results showed that, as the epoxy system content increased from 10 to 50%, the tensile strength of REAB increased from 1.2 to 3.0 MPa, whereas its elongation at break initially increased and then decreased. With increasing curing time, the viscosity of REAB showed a stagewise transition from slow growth to a rapid increase, and higher curing temperatures advanced the onset of this rapid increase. Curing-induced crosslinking markedly enhanced high-temperature stiffness and elasticity, with the rutting factor increasing by more than 110%, but reduced low-temperature relaxation capacity. The air-void content of REAM initially decreased and then increased, whereas its indirect tensile strength initially increased and then decreased. Three-factor factorial analysis of variance showed that temperature, time, epoxy system content, and their interactions had significant effects (p < 0.01). These findings clarify the stagewise evolution of epoxy asphalt reclaimed systems during curing and provide a reference for determining the allowable construction window and controlling the compaction process of epoxy asphalt reclaimed mixtures with high RAP contents.