STUDY ON EFFECT OF MICP USING BACILLUS CLAUSII

Abstract

Some soils have very low strength so it’s quite difficult to construct civil engineering structures but due to a great space requirements we used to construct these structures on those locations. Microbially induced calcite precipitation is a phenomena by which soil properties are enhanced. In this study a silty sand sample is modified using MICP, Microorganism named Bacillus clausii is used in this study and its ureolytic effects with cementation agent containing urea are examined for various time periods namely 8 hours, 72 hours (3days) and 168 hours (7days) and laboratory tests are performed on soil to determine CBR, unconfined compressive strength, and shear parameters. The results of UCS and tri-axial tests showed a significant impact of MICP on the strength properties of the soil and the effects of curing duration on the strength properties of the soil. The presence of Calcite precipitates resulted by microbial activities identified by the scanning electron microscope. The three days soaked CBR increased by 49%, unsoaked CBR increased by 65% compared to results of untreated samples, which shows increase in stiffness of soil. UCS results were highly promising as 168 hours UCS increased 4 times as compared to untreated soil specimen. Selected microorganisms and MICP is likely to play a very important role in geotechnical engineering properties involving soil improvement techniques.