Multiscale interfacial characterization and self-healing effect of cementitious materials containing absorbent microcapsules

Aiming at the problem of weak interfacial binding force between the absorbent microcapsule (SA) with calcium alginate as shell and epoxy resin E-51 as core and cement matrix, silane coupling agent was used to modify the surface of SA microcapsule to improve its interfacial binding with cement matrix, so as to improve the self-healing effect. By means of SEM, microhardness and drawing test, the interface bonding was analyzed from micro, mesoscopic to macro scale, and the self-healing effect was evaluated by the recovery rate of compressive strength and water permeability resistance of the mortar specimen after damage repair. The results show that the interface bond between SA and cement matrix is closer after modification with coupling agent KH792, the microhardness at the interface is increased by 159%, and the interface bond strength is increased by 67%. For the mortar mixed with 4wt% (cement mass) SA, the compressive strength recovery rate after load damage is 103%, and the seepage resistance recovery rate after water pressure damage is 118%. The surface modification of silane coupling agent significantly improved the interface bonding between SA and cement matrix, and the self-healing effect of cement-based materials was enhanced.