Experimental Study on Bacterial Concrete Using Bacillus Subtilis Micro-Organism

Abstract

Concrete is a homogenous mix in which the cracks are unavoidable. The seepage of water and other salts through the cracks makes concrete weaker and reduces its life. Further, corrosion of steel may also occur due to the seepage of water and salts which weakens the reinforcement in concrete. Hence, it is required to rehabilitate the concrete for economic life of structures. To remediate the cracks in concrete, an inherent biomaterial, a self-healing material, is developed using bacteria. Bacterial concrete is a technique which is highly desirable because the calcium carbonate precipitation is induced as a result of microbial activities that can heal the cracks itself. Provision of suitable conditions and calcium sources to the microbes, a few strains of microbes can prompt the precipitate the calcium carbonates in concrete. This precipitation capability has been evaluated in recent decades to justify the improvement in strength and durability properties of concrete. In this study, Bacillus subtilis bacteria was used and tested for suitability in concrete. This paper shows the impact of Bacillus subtilis bacteria on compressive strength, workability and self-healing of cracks in concrete. Results show that the addition of bacteria can increase the strength of the concrete. And the workability of bacterial concrete depends on the nutrient source, i.e. calcium lactate; addition of calcium lactate may increase the workability of concrete. However, bacteria cultures and spore powder place a minor role in workability of concrete. Both the cultured and spore powder bacteria are giving good results in healing of cracks.