Investigating the Effect of Bacillus Subtilis Bacteria and Eggshell Powder on Some Properties of Concrete

Abstract

The aim of this study is to develop and apply a biochemical agent and to verify the bacterial strain (Bacillus subtilis) used in cement mortar to improve its properties such as strength and water absorption. The use of residues with a high content of calcium with these bacteria, such as eggshell powder, has been verified and their effect on the properties of cement mortar has been investigated. bacteria were grown, diagnosed and examined for urease production activity, calcite precipitation potential and activity to improve compressive strength. Based on the results. The experimental work was carried out by casting and treating 36 cubes for each addition of bacteria and ESP in different proportions and concentrations to evaluate the effect of bacterial concentration in terms of optical density (1= OD) and ESP on pressure resistance. All samples of bacterial cement slurry and ESP showed an improvement in compressive strength and water absorption.The highest improvement in compressive strength was shown when Bacillus subtilis (DO = 1) was added over a 28-day treatment period with a ratio of 21.3% and a 27.11% increase in compressive strength was detected when 20% ESP was added to the cement mortar during the treatment period of 28 days. The compressive strength also increased and improved. for mortar samples treated by adding each of the isolated bacteria with 20% ESP at a period of 21 days, 23.04%. This identifies the file the suitability of these bacteria for use in cement mortar. the Calcium carbonates  precipitation  inside the cracks of the cement mortar were analyzed by bacterial isolation under electron microscopy (SEM) and X-ray analysis (EDX).