Strength characteristics of microbial cement mortars treated in different calcium sources

Microbially induced calcium carbonate precipitation is a method for the protection of cement-based materials. This paper deals with the strength characteristics of microbial cement mortars, which are treated by the Enterobacter sp. FJ 973550 microorganism in different calcium sources (calcium hydroxide, calcium acetate, calcium chloride and calcium oxide). The crystalline phases of calcium carbonate crystal formation and the surface morphology of cement mortar are investigated by X-ray diffraction and scanning electron microscopy. Microbial cement mortar specimens treated in calcium hydroxide source show higher compressive strength (∼29%) and tensile strength (∼47%) compared to control specimens. Surface treatment of specimens with bacteria resulted in an approximately 56% decrease in water absorption and increased the resistance to water and hazard material penetration. This biological surface treatment shows promising prospects for increasing strength and durability aspects of cement mortar specimens.