Experimental and numerical study on post-fire self-healing concrete for enhanced durability

Fire hazards pose significant risks to civil infrastructure, leading to concrete degradation. This study explores the development of post-fire self-healing concrete incorporating encapsulated or immobilized bacteria to restore structural integrity after fire exposure. Key challenges addressed include protecting bacteria during fire exposure and activating them post-fire. Innovative encapsulation techniques were developed to shield bacteria within concrete samples during fires, enabling their activation afterward to enhance structural strength. A finite element model simulated the time-temperature profile within the concrete and cement-based composites, replicating experimental conditions. Concrete samples underwent customized ISO 834 standard testing for a shorter period, open fire tests, and ultrasonic assessments to evaluate residual properties post-heating. A novel surface treatment was devised to protect embedded bacteria during fire exposure, proving effective in maintaining bacterial viability and enabling post-fire self-healing. A finite element model was employed to simulate the internal temperature profiles and assess the effectiveness of bacterial activation post-fire. The results confirm that the encapsulated bacteria can survive fire exposure and subsequently enhance the concrete's mechanical properties, marking a significant advance in fire-resistant construction materials. The research establishes critical time-temperature thresholds for the feasibility of post-fire self-healing in concrete, presenting a significant advancement in fire-resistant construction materials.