Effect of Nonureolytic Bacteria on Engineering Properties of Cement Mortar

Abstract

Bacterially induced mineral precipitation is a general phenomenon in nature. Ureolytic bacteria have been used in many studies as an environmentally friendly method for the protection and improvement of strength of cementitious materials. However, the ammonia produced by ureolytic bacteria during this biomineralization is harmful for the health. This paper incorporates a nonureolytic bacteria of the genus Bacillus, and investigates its effect on various mechanical properties of cement mortar such as compressive strength, setting time, soundness, sorptivity, and microstructural morphology. Outcomes from this study revealed that the nonureolytic bacteria performs better than ureolytic bacteria, as reported by previous studies with regard to compressive strength. The other engineering properties have also been improved by the addition of nonureolytic bacteria. This novel biological precipitation shows promising prospects for increasing the strength and durability of concrete constructions without hazard associated with generation of ammonia.