Laboratory Investigations to Optimize the Physicochemical Parameters for Bacillus cereus Inclusions in Concrete for Enhanced Compressive Strength and Chloride Resistance

A popular technique for improving the properties of concrete in recent times is microbial inclusion. Calcite precipitated by the metabolic activities of these microbes reduces the porosity of concrete and enhances its compressive strength and chloride resistance. In this study, the suitability of Bacillus cereus as a potential microbe in concrete environment is determined using laboratory experiments. Due to the absence of reported information, this study optimizes the inoculum volume, substrate volume, and pH required for growth of Bacillus cereus , prior to inclusion in concrete. The optimal proportions of bacterial solution to improve the compressive strength and chloride resistance are determined. Additionally, the optimal quantity of calcium lactate nutrient required for bacterial growth in concrete are also determined. It is observed that addition of 1% solution of Bacillus cereus in concrete results in 14–23% increase in compressive over a period of 90 days. Additionally, it is observed that the corresponding reduction in chloride permeability is nearly 19% compared to traditional concrete. These findings are validated using mineralogical, chemical, and microstructural analyses.