Researchers and construction-material companies are developing “self-healing” concrete designed to seal small cracks before water and salts penetrate deeply enough to damage reinforced structures. Concrete that repairs itselfBacterial self-healing systems incorporate microorganisms and nutrients into concrete, often using protective carriers or encapsulation. Self-healing concrete should therefore be viewed as a complement rather than a substitute. Self-healing systems seek to reduce those interventions by sealing microcracks before they become pathways for moisture and chlorides. Self-healing concrete will not mean the end of cracks, nor can bacteria compensate for poor construction or serious structural damage.