Although various self-healing methods have been suggested until recently, these methods have merits and demerits. The utilization of expansive agents and mineral admixtures in various methods may be appropriate due to their good healing efficiency, compatibility with the cement matrix, and low cost, but the efficiency of healing products generated by necessity is not guaranteed. In this study, granulation/coating methods are applied to expansive agent. The self-healing time of materials can be controlled via water-soluble film thickness until cracks occur, and healing products will be formed because materials react with moisture via the crack faces after water-soluble film was dissolved by moisture. It was verified through various tests that the granulated expansive agent with water-soluble film coating can control the time of self-healing and can prevent water migration via crack closing.

Keywords: Self-healing, Expansive agent, Water-soluble film, Crack.