Isolation and Identification of Ureolytic Bacteria Isolated from Livestock Soil to Improve the Strength of Cement Mortar

Abstract

The aim of the present study is to isolate and recognize calcium carbonate-producing bacteria and to check these bacterial strains for use in cement mortar to improve its properties such as strength and water absorption. Bacteria were isolated from livestock soils were examined for urease producing activity, the possibility to precipitate calcite and its activity to improve the compressive strength. Based on the results, four isolates were selected and identified. They were characterized as B. atrophaeus, B. subtilis, B. aryabhattai and B. amyloliquefaciens. Experimental work was performed to evaluate the effect of bacterial concentration in term of optical density (OD) on the compressive strength. Bacterial cement mortar samples revealed improvement in compressive strength and water sorptivity. The efficiency of bacterial strains towards crack remediation was also investigated. Considerable increase in compressive strength and complete cracks remediation was detected in cement mortar samples cured with all bacteria isolate (using OD=1). This specifies the suitability of these bacteria for use in cement mortar. The precipitate of calcium carbonate inside the cracks of cement mortar by bacterial isolate was analyzed under a scanning electron microscope (SEM).