Review on autogenous self-healing technologies and multi-dimension mechanisms for cement concrete

Micro-cracks inevitably form in cement concrete structures, presenting substantial risks to safety, service life, and eco-efficiency. Developing high-intrinsic self-healing concrete offers a promising approach to promptly alleviate issues caused by microcracks. These issues include rapid matrix degradation and frequent maintenance requirements. This paper reviews recent advancements in autogenous self-healing concrete technologies. It discusses their classification, efficiency, and mechanisms based on concrete component categorisation, normalisation methods, and statistical analyses. Results indicate that intrinsic self-healing relies heavily on the physical and chemical properties of the concrete, external water, and crack dimensions. Several methods for adjusting concrete component parameters, types, and proportions enhance self-healing capability. In addition, minimising crack width proves beneficial. Enhancement mechanisms of each technology demonstrate significant diversity and complexity due to the intricate self-healing process. They primarily fall into three categories: mechanical mechanisms (microparticle accumulation, fibre bridging), physical mechanisms (swelling, ion adsorption, matrix porosity, roughness, crack width), and chemical mechanisms (improved hydration reaction, expansion product generation, precipitation reaction mechanisms, complexation-precipitation and chelation reactions).