Influence of Accelerator Dosages on the Viscosity–Time–Temperature Characteristics, Morphology, and Mechanical Properties of Hot Mix Epoxy Asphalt

To address the contradiction between high-temperature construction retention time and normal-temperature curing time of hot mix epoxy asphalt (HEA), in this paper, 2,4,6–tris (dimethylaminomethyl) phenol (TAP) was selected as the accelerator, and the viscosity–time–temperature (VTT) characteristics and the curing rate of the HEA were modulated by varying the accelerator dosage. The VTT characteristics of the HEA during the paving–rolling stage were quantitatively characterized by a rheometer for the first time, and the effect of accelerator dosages and thermal histories on the VTT characteristics of the HEA during the mixing–rolling stage were systematically analyzed. Additionally, the effect of the accelerator dosages on the morphology, curing rate, and mechanical properties of the HEA were thoroughly assessed. The incorporation of accelerator can effectively decrease the reaction activation energy of the hot mix epoxy resin (HER) while maintaining the reaction order without significant alteration. The viscosity of both HER and HEA during the mixing–rolling stage can be precisely regulated by adjusting the dosage of the TAP. Due to the dilution effect of the matrix asphalt, the VTT characteristics of HEA are markedly diminished under varying thermal history conditions when compared with HER, thereby facilitating on-site construction control. The incorporation of an appropriate quantity of accelerator effectively mitigates the coalescence behavior between the epoxy phase and the asphalt phase, thereby substantially enhancing the microstructural homogeneity of the HEA. As the dosage of the accelerator progressively increases from 0% to 2%, both the tensile strength and loss factor of HEA exhibit a trend of initially increasing rapidly and subsequently leveling off gradually. This study is expected to enhance the characterization and regulation of the workability of the epoxy asphalt throughout the construction process.