Interfacial adhesion failure is the primary limiting factor in the long-term durability of epoxy-emulsified asphalt micro-surfacing pavements. However, while digital image correlation (DIC) has been extensively applied to evaluate the bulk fatigue of traditional hot-mix asphalt and concrete, its specific application to the complex bi-material interface between rigid concrete substrates and cold-mixed, thermosetting epoxy-asphalt overlays remains limited. Consequently, current research lacks real-time data on full-field strain evolution and the transitional damage localisation mechanisms during dynamic fatigue processes under extreme temperature gradients. To this goal, three-point bending fatigue tests were performed at various temperatures (ranging from −10°C to 45°C). The fatigue damage behaviour at the contact was quantified by combining digital image correlation (DIC) with fracture mechanics calculations. The results show that the fatigue life at the contact follows a non-monotonic “bell-shaped” trend, peaking at 15°C. At a low temperature of −10°C, fatigue life is reduced by 78% compared to the peak value. DIC research indicated that strain localisation was the dominant failure mode, resulting in brittle fracture. At 45°C, despite an exponential increase in the interfacial fracture energy release rate (Gc) due to viscous dissipation, fatigue life was reduced by 90%. At 45°C, the interfacial failure mechanism transitions from localised crack propagation to extensive viscoplastic shear flow. This indicates that high-temperature failure is primarily driven by matrix softening and a critical loss of internal shear strength. The findings suggest that the enhancement in performance at 15°C is attributable to the synergistic interaction between the epoxy resin network (which provides stiffness) and the bituminous phase (which promotes relaxation). This method has been demonstrated to be an effective means of preventing both low-temperature brittleness and high-temperature viscoelastic deformation.
Tan et al. (Thu,) studied this question.