Self Healing of Concrete using Bacteria

Abstract

The concrete structures deteriorate in contact with the surroundings which lead to an irreversible damage and ultimately reducing the strength of the structure. The characteristics of pore structure of concrete have a direct influence on its durability. The durability and strength of concrete can be enhanced by using a novel technique which involves bacterial-induced calcite precipitation. Bacteria are capable of precipitating calcium carbonate by providing heterogeneous crystal nucleation sites in super-saturated CaCO3solution.Bacteria are believed to affect carbonate precipitation both through affecting local geochemical conditions and by serving as potential, nucleation sites for mineral formation. A novel technique for the remediation of damaged structural formations has been developed by employing a selective microbial plugging process, in which metabolic activities promote precipitation of calcium carbonate in the form of calcite. Recently, microbial mineral precipitation resulting from metabolic activities of some specific microorganisms in concrete to improve the overall behavior of concrete has become an important area of research. It has been hypothesized that almost all bacteria are capable of CaCO3 production because precipitation occurs as a byproduct of common metabolic processes such as photosynthesis, sulfate reduction, and urea hydrolysis.