Abstract
The main weakest point of concrete is its exposure to cracks, and concrete structure repair is expensive, especially for infrastructure maintenance, which is difficult to access. The ability of self-healing concrete (SHC) to successfully heal fractures without the assistance of humans has received much attention since it increases operational life and lowers maintenance expenses. This paper reviews various techniques and technologies of autogenous and autonomous self-healing concrete. Much more attention is given to the autonomous SHC, including the encapsulation materials, capsule geometries, and healing agents. This is due to its accuracy for healing locations and better healing capabilities compared to the uniform hydration of autogenous SHC. Polymeric materials have shown great potential in both capsules and healing agents. Because they can meet the unusual demands of capsules, which include being flexible when mixing concrete and becoming brittle when cracks develop, the healing agent's viscosity must be low enough to allow it to flow out of the capsules and fill tiny cracks. In contrast, if the viscosity is too low, the healing agent will either seep out of the fracture or be absorbed by the pores of the concrete matrix. Additionally, some projects have been cited to demonstrate the feasibility of self-healing concrete in the construction industry.