An Experimental Study on Self-remediating Bacterial Concrete

The bacterial concrete is a self-remediation biomaterial under favorable conditions. Bacteria can precipitate calcite in concrete or form a layer of calcite precipitation which plays an important role in remediation of the plastic shrinkage microcracks thereby increasing the long-term structural integrity and durability of concrete. This study investigates the impact on compressive strength of concrete by addition of aerobic microorganism such as Bacillus subtilis and Bacillus megaterium, which microbiologically induce the mineral precipitation. The bacteria were incorporated into the 100 mm concrete cube in different concentrations in two stages formerly by curing in distilled water and later by curing in peptone-based nutrient medium. The results show the positive impact on compressive strength of concrete cubes with an increase in the strength of 30% with Bacillus megaterium. The strength enhancement is due to the precipitation of calcite within the pores which in turn improves the pore structure of the concrete. The study also revealed the importance of culture media, type of microorganism and cell concentration on the strength properties of bioconcrete. However, there was no much improvement in strength by curing in nutrient medium.