Staged Formulation Design and Rheological Characterization of Ambient-Temperature-Cured Epoxy Asphalt Binders

Conventional epoxy asphalt binders are typically prepared at elevated temperatures and cured under relatively high-temperature conditions. However, the development of strength and the balance between strength and deformation capacity under ambient-temperature curing conditions remain insufficiently investigated. In this study, a staged formulation design approach was proposed for epoxy asphalt binders cured at 25 °C, involving reactive diluent screening, optimization of the blended curing system, and adjustment of the asphalt content. The macroscopic storage homogeneity of the uncured blends was evaluated using the softening point difference between the upper and lower portions after storage. A two-factor full factorial design involving the D400/D2000 ratio and DMP-30 dosage was employed to investigate tensile properties over curing periods of 2–7 days. The high- and low-temperature rheological responses of representative binders were subsequently characterized using dynamic shear rheometry (DSR) and bending beam rheometry (BBR), respectively. HA17 exhibited an observed mean tensile strength of 2.30 MPa and an elongation at break of 87.59% after curing at 25 °C for 7 days. The representative formulations showed different tensile and rheological responses, from which HA17 was selected as a candidate within the investigated formulation range. The results provide an experimental basis for the formulation design of ambient-temperature-cured epoxy asphalt binders.