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Evaluation of Shear Strength Parameters of Sandy Soils upon Microbial Treatment

Pakbaz, M. S., Behzadipour, H., Ghezelbash, G. R.
Geomicrobiology journal 2018 v.35 no.8 pp. 721-726
Sporosarcina pasteurii, bacteria, calcite, calcium chloride, cohesion, enzyme activity, friction, methodology, sandy soils, shear strength, soil sampling, soil stabilization, urea, urease
A new method for soil stabilization known as microbial-induced calcite precipitation (MICP) has been the focus of research in this area during the last decade. In this method, the reaction of microorganisms in the presence of urea and calcium chloride is used to produce calcite. Despite the large numbers of bacteria in soil, Sporobacillus pasteurii (previously known as Bacillus pasteurii) has the most capability to create cementation between soil particles in the MICP method due to its high urease activity. In this paper, the effect of MICP treatment on the shear strength characteristics of a sandy soil was studied. The change in the shear strength of sandy soil upon MICP treatment was measured using a strain-controlled direct shear test before and after treatment of the soil samples. The results showed an increase of 44–86% in the shear strength of the sandy soil after 15 days of MICP treatment compared to the untreated soil. The enhanced shear strength was the result of an increase in both the cohesion intercept and angle of internal friction. The increase in the cohesion intercept was more significant than the increase in the angle of internal friction.