Research on compatibility mechanism of biobased cold-mixed epoxy asphalt binder

•ESO made asphalt disperse uniformly and increased elongation at break of the CEA.•ESO did not react chemically with asphalt and epoxy monomer.•ESO changed the cohesion energy densities and solubility parameters. Cold-mixed epoxy asphalt (CEA) has attracted increasing attention as a superior steel bridge pavement material for its convenient construction and low energy consumption. In this paper, the compatibility of CEA was improved with incorporating biobased epoxidized soybean oil (ESO), and the micromorphology, dynamic mechanical properties, and mechanical properties were evaluated. The results showed that ESO made asphalt particles disperse uniformly, and decreased the number of the glass transition temperature of the CEA. ESO also increased elongation at break of the CEA. The compatibility mechanism was analyzed according to Fourier transform infrared spectrum and molecular dynamics simulation. The results showed that ESO did not react chemically with asphalt and epoxy monomer. Due to incorporating ESO into CEA, the difference values of cohesion energy densities and solubility parameters between asphalt and epoxy monomer decreased, while the interaction energy of the whole system strengthened.