Temperature adaptive microcapsules for self-healing cementitious materials

The brittleness of microcapsule shell greatly restricts its self-healing performance since it is easily ruptured during the mixing process. Based on the heat releasing nature during cement hydration, a novel concept of temperature-adaptive microcapsule (TAM) was proposed, which can exhibit a switchable mechanical property with temperature. In this paper, a series of TAM with polymethylmethacrylate-methacrylate shell and magnesium oxide core was prepared with four designed transition temperature, and were characterised by Fourier transform infrared spectroscopy, nano-indentation tests, scanning electron microscopy, thermalgravity analysis and particle size analysis, which confirmed the success in preparing the TAM. Moreover, the performance of proposed microcapsules in cement was investigated by determining the breakage rate of microcapsule and recovery rate of cement paste under different mixing temperature. The results illustrated that compared to lower mixing temperature, a 75% reduction in breakage rate and a 5% increment in recovery rate was observed in TAM embedded cementitious paste at an elevated mixing temperature. This work should provide a promising approach to improve the performance of microcapsules for self-healing cementitious materials.

Automated summary

The concept of temperature-adaptive microcapsule (TAM) was proposed to address the brittleness issue of microcapsule shell, and a series of TAM with different transition temperatures were successfully prepared. The performance of TAM embedded in cementitious paste showed a significant reduction in breakage rate and an increment in recovery rate at an elevated mixing temperature compared to lower mixing temperature. This work demonstrates a promising approach to enhance the performance of microcapsules in self-healing cementitious materials.