Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Ureolytic bacteria, Cement mortar


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

Hussein J. Khadhim; Saad H. Ammar; Shahlaa E. Ebrahim

Engineering and Technology Journal, 2019, Volume 37, Issue 3C, Pages 319-326
DOI: 10.30684/etj.37.3C.3

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)