Effect of Various Calcite Precipitating Bacteria on Compressive Strength of Concrete: A Comparative Study

Abstract

The presence of micro pores in concrete makes the concrete weak and less durable, in this study an ecofriendly attempt has been made to minimize these micro pores by calcite precipitating bacteria i.e. Escherichia Coli, bacillus subtilisand pseudomonas aeruginosa which produce calcium carbonate when they blend with calcium lactate in presence of water and air thus filling up the micro pores, thus comparing their effects on compressive strength of concrete.Various proportions of E. coli, B.subtilisand P. aeruginosa bacterial media were impregnated in concrete viz. 10%,20% and 30% replacing the proportion of mixing water, small proportion of fine aggregate was also replaced by calcium lactate and silica gel. It was observed that concrete with 10% replacement of P. aeruginosa culture media with mixing water showed maximum compressive strength with 79.6% increase in the compressive strength of concrete where as concrete with B.subtilisbacterial media showed 61.1% increase in the compressive strength of concrete and concrete with E.coli bacterial media showed 23.5% increase in the compressive strength of the concrete, keeping 10-6 cells/ml the cell concentration for all bacterial concretes.