Design and performance of epoxy asphalt based on hydroxyl-ester dynamic crosslinking network

Conventional epoxy asphalt is difficult to reuse due to its thermosetting inability to heal and reprocess. In this study, using dimer acid (DA) and zinc acetate (Zn(OAC) 2 ) as curing agent and catalyst, respectively, and the hydroxyl-ester bonds were introduced into the dynamic crosslinking network system of the asphalt, a highly compatible epoxy asphalt DEA with heat recovery performance was designed. On this basis, the effects of different contents of capped hyperbranched polyester HP102 on the mechanical properties, low-temperature properties, and compatibility of DEA were investigated. The results showed that the base asphalt was successfully grafted with hydroxyl and ester groups, and this chemical modification effect reduced the polarity between the asphalt phase and the resin phase, resulting in a notable improvement in the compatibility of DEA compared with commercially available epoxy asphalt. The introduced HP102 improves not only the low-temperature ductility of the material but also its structural presence of -COO- groups, which can be further used to realize the dynamic exchange and reorganization of hydroxyl-ester bonds, which contributes to the modulus relaxation of the material and enhances its mechanical properties and self-healing ability. The highly branched structure of HP102 increases the unoccupied space and undergoes stress relaxation, which contributes to the improvement of the low-temperature ductility of the material. In addition, the cyclic tensile test results show that the mechanical property recovery rate can reach 86.7 % when hot-pressing processed at 180 °C for 5 h, which confirms that the epoxy asphalt under the reversible covalent crosslinking network possesses non-negligible recycling potential, and provides an engineering application reference for the hot-pressing recycling of epoxy asphalt.