Effects of Bacillus Subtilis on the compressive strength, porosity and rapid chloride permeability of concrete

Abstract

Durability enhancement of concrete structures is an interesting issue which is fascinating many scientists in all fields. The application of bacteria in concrete has become an important area and a promising solution for sustainable concrete. This study investigates the effects of nutrients and bacteria Bacillus Subtilis on compressive strength, porosity, water absorption and rapid chloride permeability at different ages. Test results indicate that the addition of Bacillus Subtilis enhances the compressive strength and reduces the porosity as well as the chloride permeability of concrete. The main production of this processing is the microbial precipitation (CaCO₃) induced by the metabolism of bacteria. This precipitation, by filling up the pores, reduces the porosity and makes the concrete denser. This phenomenon enhances the resistance to chloride ingress and increases the compressive strength. The finding of this investigation indicates that bacterium with nutrients could act as a promising admixture and could improve the durability of cementitious materials.