Performance of temperature adaptive microcapsules in self-healing cementitious materials under different mixing temperatures

Abstract

The ease to be ruptured during mixing due to the brittleness of microcapsule shell limits the self-healing performance of microcapsules in concrete. In this study, a novel type of microcapsule with temperature-adaptive property (TAM) under different mixing temperatures was proposed to tackle this issue. The effect of TAM content and mixing temperature in self-healing cementitious materials was investigated. Based upon the confirmation of temperature adaptivity of microcapsule shell by dynamic mechanical analysis, the early age properties, including minislump, setting time and hydration heat, and the hardened properties of compressive strength and shrinkage, were determined. Moreover, the self-healing performance, in terms of strength healing and recovery rate, as well as the pore structures, of TAM in cementitious material was investigated. The results showed that the addition of TAM decreased workability and slightly extended the setting and hydration of cement, while the elevation of mixing temperature reduced workability and accelerated the setting and hydration of cement. Moreover, the addition of TAM and low mixing temperature reduced the compressive strength and shrinkage of hardened paste. Compared to the low mixing temperature, the self-healing performance in terms of strength and chloride migration was improved at high mixing temperature. The results proved the design concept of temperature adaptive microcapsules.