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 calciumcarbonate-producing bacteria and to check these bacterial strains for use incement mortar to improve its properties such as strength and water absorption.Bacteria were isolated from livestock soils were examined for urease producingactivity, the possibility to precipitate calcite and its activity to improve thecompressive strength. Based on the results, four isolates were selected andidentified. They were characterized as B. atrophaeus, B. subtilis, B. aryabhattaiand B. amyloliquefaciens. Experimental work was performed to evaluate theeffect of bacterial concentration in term of optical density (OD) on thecompressive strength. Bacterial cement mortar samples revealed improvementin compressive strength and water sorptivity. The efficiency of bacterial strainstowards crack remediation was also investigated. Considerable increase incompressive strength and complete cracks remediation was detected in cementmortar samples cured with all bacteria isolate (using OD=1). This specifies thesuitability of these bacteria for use in cement mortar. The precipitate of calciumcarbonate inside the cracks of cement mortar by bacterial isolate was analyzedunder a scanning electron microscope (SEM)

Keywords

• ureolytic bacteria, cement mortar
• compressive strength, crack remediation