Design and optimization parameters of cement-based spherical macrocapsules for self-healing cement applications

Abstract

Encapsulated healing agents is a promising solution for extending the service life of critical infrastructure, providing long-term healing efficiency. This research focuses on the shell properties of cement-based spherical macro-capsules, aiming to achieve increased survivability during mixing of mortar mixtures and efficient triggering upon crack propagation. In this framework, the pan coating technique was examined for the production of capsules with a cementitious shell, developed for the protection of powder healing agents. The main properties that were studied included the crushing load as a function of capsules size and the shell hydration facilitated by different setting accelerators, and their consequent effect on the survivability and the triggering efficiency of the capsules. The results show that the use of setting accelerators allows the rapid densification of the shell microstructure and improves the crushing load of capsules, resulting in high survivability during mixing process. The enhanced compatibility of capsules with the matrix allowed the efficient triggering of capsules during crack propagation, initiating the autonomous healing process.