An Appraisal of Autogenous and Autonomous Self-Healing in Concrete in Building Construction

Concrete is a brittle material and is prone to cracking. Crack repairs are not only expansive but also increases the carbon footprint as it is 2nd most used material on earth. Designing a novel concrete material possessing the ability to self-repair cracks would enhance its sustainability and reduce the maintenance cost as well. Self-healing can be described as the ability to repair the damages itself without any external intervention or help. Self-healing process in concrete can be autogenous (based on an optimal mix composition) or autonomous (when additional capsules containing some healing agents are inserted into binder phase). The first approach that is in autogenous, unhydrated cement particles are used to mend the fracture, while in autonomous method bacteria is used to precipitate calcite, which is released into the crack from a broken capsule which is activated by water and oxygen. The disadvantage of autonomous approach is the loss of fresh concrete workability, low efficiency, and bacteria survival during mixing and also its high cost. On the other hand, autogenous self-healing has been found to be more efficient, cost effective, and safe