摘要
Internal microcracks that occur in cement-based materials during the service process could be self-repaired using microcapsules. However, the chemical activity of the repairing agent is affected by the external environment. In this paper, the self-repairing ability of mortar containing paraffin/toluene-di-isocyanate (TDI) microcapsules was studied under different external environment (humidity and temperature). The pore size distribution , mechanical properties , impermeability and surface crack width of the control mortar (CM) and mortar containing microcapsules (MM) were measured and compared. The reaction kinetics of TDI during the self-repairing process of MM was investigated using pseudo-first-order and pseudo-second-order kinetics models. The self-repairing ability of MM was enhanced when increasing RH (relative humidity) from 50% to 95% at 20 ℃. When MM was kept under 60%f c0 pre-load and allowed 7 d for self-repairing at a relative humidity of 95%, the proportion of harmful pores, compressive strength reserved ratio and chloride diffusion coefficient recovery ratio were 28.1%, 80.9% and 68.1%, respectively, and cracks with an initial width of 0.4–0.5 mm self-repaired within 6 h. With the increasing of temperatures, the self-repairing ability increased at first but then declined. When the temperature was 50 ℃ at 50% RH, the proportion of harmful pores, compressive strength reserved ratio and chloride diffusion coefficient recovery ratio of MM under 60%f c0 pre-load for 7 d of self-repairing were 25.8%, 83.5% and 72.1%, respectively, and cracks with an initial width of 0.4–0.5 mm self-repaired within 5 h. Under different external environment and pre-loads, the curing reaction of TDI during the self-repairing process of MM was a pseudo-second-order kinetics model, which indicated that the humidity and temperature had a significant impact on the self-repairing ability of the mortar.
危险品化学品经营许可证（带存储）