A review: Self-healing in cementitious materials and engineered cementitious composite as a self-healing material

Cementitious materials are the most widely used building materials all over the word. However, deterioration is inevitable even since the very beginning of the service life, then maintenance and repair work, which are often labor- and capital-intensive, would be followed. Thus, self-healing of the affected cementitious materials is of great importance. Self-healing phenomenon in cementitious materials has been noticed and been studying for a long time. The possible mechanisms for self-healing phenomenon in cementitious materials, which are summarized based on substantial experimental studies and practical experience, are reviewed. In order to endow or enhance the self-healing property of cementitious materials, many different and innovative strategies have been proposed and developed during the past decades. Then the different strategies employed for the self-healing of cementitious materials, i.e. the use of hollow fibers, microencapsulation, expansive agents and mineral admixtures, bacteria and shape memory materials, are reviewed and summarized. A comparison study is conducted subsequently on different strategies to self-healing and on different healing agents used as well. Engineered Cementitious Composite (ECC) is a new type of cement-based materials, which has unique properties compared with traditional cementitious materials. Further, a summary about the research status of self-healing on ECC is given. It shows that ECC bears great potential in realizing effective self-healing due to its unique micro-crack behavior and tight crack-width control property combined with its relatively high percentage of cementitious components and low water–binder ratio.