Strength and toughness attenuation mechanism of biobased cold-mixed epoxy asphalt under freeze–thaw cycles

Biobased cold-mix epoxy asphalt (BCEA) was prepared by adopting biodiesel and epoxy soybean oil as asphalt solvent and compatibilizer. The strength and toughness attenuation laws under freeze–thaw (FT) cycles of BCEA were studied through tensile tests, flexural tests, and dynamic mechanical analysis. The attenuation mechanism was explored through scanning electron microscopy, Fourier transform infrared spectroscopy and water absorption tests. The results showed that the first FT cycle significantly weakened the strength and toughness of BCEA. After the third cycle, the attenuation rate of storage modulus, loss tangent, and glass transition temperature of BCEA declined. The attenuation mechanism of BCEA is as follows: (1) post-curing and destruction of the cross-linking network, (2) agglomeration and aging of asphalt, and (3) diffusion and reaction of water. This research provided a theoretical basis for the application of BCEA.