Visualized tracing of crack self-healing features in cement/microcapsule system with X-ray microcomputed tomography

A novel type of microcapsule-based self-healing material which holds promise for crack-healing of concrete in a marine environment is designed and prepared, in which the calcium sulfoaluminate cement (CSA) is used as the healing agent. In the present work, X-ray microcomputed tomography (X-ray μCT) is innovatively applied to study the crack-healing process of the microcapsules based self-healing system. The healing mechanism is further analyzed by means of scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS). The experimental results demonstrate that the microcapsule-based self-healing system is feasible and effective. The initial cracks are dramatically restored with the fill of the hydration product brought about by the CSA and water. The extent and rate of the self-healing process strongly depend on the transport of water from the surface to the body of the cementitious materials. The healing efficiency is up to 82.60% according to the volume variation of the cracks.