Microbially Induced Calcium Carbonate Precipitation for Self-Healing Concrete: Mineralization Mechanisms, Durability Recovery, and Functional Carriers including Solid-Waste-Derived Materials

Abstract

Microbially induced calcium carbonate precipitation (MICP) can promote in situ calcium carbonate formation within concrete pores and cracks and is therefore being investigated for autonomous crack repair and durability recovery. This narrative review synthesises peer-reviewed evidence on MICP metabolic and mineralisation mechanisms, microbial survival and protection in cementitious environments, crack-healing behaviour, recovery of mechanical and transport properties, and carrier systems, with targeted updating of the literature through July 2026. Particular attention is given to the relationship between microbial activation, reaction-transport limitations, spatial mineral deposition, and functional recovery, as well as to recycled concrete aggregate, industrial by-products, and waste clay brick as potential components of carrier design. The evidence indicates that high alkalinity, pore refinement, desiccation, and restricted water and oxygen supply can limit long-term microbial activity. Immobilisation and encapsulation improve protection, but total calcium carbonate production, visible crack closure, internal filling, and macroscopic durability recovery are not directly interchangeable measures. Direct carrier evidence is strongest for recycled concrete aggregate and selected engineered porous or coated systems; waste clay brick remains a plausible but insufficiently validated carrier candidate. Future work should prioritise long-term reactivation, deep-crack healing under realistic exposure, standardised functional assessment, life-cycle and implementation constraints, waste-derived multifunctional carriers, and coupled reaction-transport prediction.