Bacterial Self-Healing Concrete for Sustainable Infrastructure Maintenance

Abstract

The deterioration of concrete infrastructure due to cracking remains a critical challenge in civil engineering, demanding frequent repair interventions that incur significant economic and environmental costs. This paper investigates the application of microbially induced calcite precipitation (MICP) for autonomous crack repair in concrete structures. Four bacterial strains Bacillus subtilis, Bacillus megaterium, Sporosarcina pasteurii, and Bacillus sphaericus were incorporated into ordinary Portland cement (OPC) concrete specimens at varying cell concentrations. Compressive strength, crack healing efficiency, water permeability, and microstructural characteristics were evaluated over a 90-day curing period. Results demonstrated that S. pasteurii at 10⁶ cells/mL achieved the highest compressive strength improvement (32.5% over control at 90 days) and crack healing efficiency of 97% for cracks up to 0.4 mm width. Water permeability was reduced by 75.4% compared to control specimens. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the deposition of calcite crystals within the crack matrix. These findings support the viability of bacterial self-healing concrete as a sustainable solution for extending infrastructure service life while reducing maintenance costs and carbon emissions associated with conventional repair methods.