Biomineralization of calcium carbonate in bioconcrete by the action of Bacillus subtilis ATCC 6633

Abstract

In this study, the viability of bacterium Bacillus subtilis (ATCC 6633) as a biological agent in the process of precipitation of calcium carbonate (CaCO₃) on the surface of concrete was investigated. This evaluation was first carried out in a curing tank for concrete samples, using a nutrient solution enriched with B. subtilis for comparison with control samples without the addition of microorganisms. The biomineralized samples with B. subtilis showed a 21.01% reduction in void content and a 25.31% reduction in water absorption by capillarity. Due to the surface protection, the microorganisms reduced the porosity of the material, resulting in an increase in compressive strength of about 6.41%. The mineral morphologies analyzed by SEM included cubic, polygonal and rhombohedral crystals. Chemical evaluation by EDX and characterization by XRD of the bioconcretes indicated the presence of CaCO₃ precipitated by the bacteria. The results obtained show that the superficial application of B. subtilis (ATCC 6633) on concrete leads to an improvement in mechanical and durability properties.