Investigation of Bacterial Capsule as a Self-healing Agent in Cement Mortar

Mortar is an important material used in building construction. Because of some stresses, the material tends to crack. The cracks are mainly caused by the penetration of some liquids, gases, and dust. If the cracks are not treated instantly, then the cracks will expand further and finally it requires a high repairing cost. For reducing the repairing cost and to increase the strength of structure, a bacterial solution is required. A soil bacterium was used to precipitate calcium carbonate (CaCO3), and the process of metabolism of urease enzymes which will heal the cracks is formed in the mortar specimen. Here, the bacterial strain, Bacillus licheniformis MTCC3606, was used for calcite precipitation to seal the cracks. Urease analysis has shown the secretion of urea which is responsible for calcite precipitation. SEM analysis has shown the calcite precipitation inside the foam strip of bacterial cement mortar. Therefore, the nature of the study was to investigate the possible application of Bacillus licheniformis as a self-healing agent in mortar mixtures to seal the cracks.