Experimental evaluation of self-healing concrete: Strength enhancement and microstructural characterization

Concrete, despite its widespread use and durability, remains susceptible to cracking from environmental and mechanical stressors. This study explores an innovative approach to enhancing both the strength and microstructural analysis of concrete through self-healing mechanisms and supplementary cementitious materials. Bacillus subtilis bacteria and silica fume were incorporated into M20-grade concrete, with silica fume replacing 15% of cement by weight and bacterial concentrations varied from 0 to 15 ml/L. The bacteria facilitate calcium carbonate precipitation within microcracks, contributing to autogenous healing. Experimental results demonstrate a strength increase of up to 29.10% in bacterial-silica fume concrete compared to conventional mixes. The synergy of microbial activity and silica fume fineness significantly enhances the mechanical and microstructural properties of concrete. These findings underscore the potential for integrating biological and pozzolanic components in sustainable construction practices.