Self-Healing Effect of Various Capsule-Core Materials on Asphalt Materials

To further investigate the self-healing mechanism of microcapsules and exclude the interference of capsule-wall materials, a bi-plate test and a molecular model of asphalt and capsule-core materials were established using dynamic shear rheometer (DSR) and molecular dynamic (MD) simulation. Firstly, the models of asphalt-rejuvenator-asphalt and asphalt-epoxy resin-asphalt were established to simulate the interface of asphalt and capsule-core materials. The cross-linking between poxy resin and curing agent, and tensile tests were then simulated through Perl scripts. Finally, the bi-plate DSR test was applied to reveal the different action mechanisms between core materials and asphalt materials. The results showed that the cohesive energy of the epoxy resin and asphalt is greater than that of the rejuvenator at the same simulation time. Meanwhile, the maximum stresses generated after stretching for the two models were 69.9 and 34.68 MPa, respectively. The healing indexes HI1 and HI2 have a sound linear correlation with the maintenance time. The HI1 value of the epoxy resin is greater than that of the rejuvenator, and the maximum value exceeds 1. This implies that the capsule core of epoxy resin can recover the strength of damaged asphalt in a short time. Epoxy resin should be considered for asphalt cracks caused by heavy-load shear.