Microbial precipitation of calcium carbonate in cementitious materials – A critical review

The article reviews the application of soil living bacteria in concrete. Formation of cracks and subsequent degradation in concrete are the critical durability phenomenon. For protection against cracking, the repair and regular maintenance by traditional methods are found to be costly. Taking notes from biomimicry and biotechnology in concrete from various literature, the role of bacteria on self-healing of cracks and the indirect benefits to strength and durability property of concrete were consolidated and presented. Amid the different microbial species investigated by researchers, bacillus sphaericus have shown greater precipitation of calcium carbonate (CaCO3) with the cell concentration of 105 cells/ml. The hydrolysis of urea has shown a significant result in the precipitation of CaCO3. Thus, the conjunction of bacillus sphaericus with urea hydrolysis could be an optimum way for biomineralization of CaCO3. The shell life of microbes can be extended by encapsulation into the carrier materials (Eg: expanded clay, perlite etc). The large-scale production of bacterial concrete requires sophisticated laboratory for culturing of microbes and preparation of media. Due to these technical constraints, the application of novel bacterial concrete is at the laboratory level.