STUDY ON THE STRNGTH AND DURABILITY OF SELF HEALING CONCRETE

Abstract Self-healing concrete has developed as a potentially beneficial material for extending the durability and performance of infrastructure due to its ability to autonomously heal cracks and reduce repair efforts. This review compiled findings from five recent studies evaluating the performance of mechanical strength and durability of various self-healing concrete systems and the use of bacteria to heal cracks. The results consistently demonstrated that adding microorganisms, for instance, Bacillus subtilis, even when encapsulated in an expanded clay or natural fibers, results in greater compressive, tensile, and flexural strength than unmodified concrete. After cracking of the specimens, strength recovery ranged between 40-60% after 28-63 days, depending on the type of healing environment (water or air) and bacterial viability. For durability, self-healing concrete has demonstrated better than unmodified concrete: sulfate attack, freeze-thaw cycles and permeability due to the bio-mineralization of calcium carbonate that sealed microcracks. Microstructural evaluation of cured self-healing concrete specimens also identified denser, less porous matrices than unmodified concrete. These results correlate with mechanical restoration from physiological or biological micro-repair but provide inconclusive evidence that self-healing concrete improvements fully restores mechanical behavior. Nevertheless, self-healing concrete can restore mechanical strength after mechanical damage and significantly enhance durability performance, and offer sustainable and resilient engineering solutions for the future of sustainable construction.