Post-treatment bacterial self-healing for high-temperature-induced damage in concrete: toward enhanced durability and sustainability

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This study presents a post-treatment bacterial self-healing strategy for restoring concrete damaged by high-temperature exposure. Concrete specimens were thermally treated at 600 °C and 800 °C, then immersed in solutions containing Sporosarcina pasteurii or Bacillus sphaericus. Compressive strength tests revealed that heat exposure caused a 31–44% strength reduction, while subsequent bacterial treatment recovered strength by up to 93%, particularly in specimens treated with S. pasteurii at 600 °C. Rapid Chloride Penetration Tests (RCPT) showed that chloride ion permeability increased by 45–60% after thermal damage but was reduced by approximately 30% following bacterial healing. Microstructural analyses using SEM and EDS revealed calcium-rich precipitates within cracks, morphologically consistent with microbially induced calcium carbonate formation. The integrated life cycle assessment further suggests potential environmental advantages of this approach relative to conventional repair methods, supporting progress toward improved sustainability; however, these sustainability inferences are model-based and require validation in field applications.