Experimental Study to Improve the Shear Stress of Silty- Sandy Soils by Using Urease Producing Bacteria

Mohammed A. Ibrahim, Raid R. Al-Omari, Mustafa H. Ibrahim


In this paper, microbial calcite cementation that affect the properties of soil specially shear strength was achieved by using the common soil microorganism Bacillus Pasteurii and cementation reagent containing urea and calcium chloride. While a number of significant factors can affect the success of the microbial treatment, this study focused on the effects of microorganisms on the shear strength of silty sandy soils where the treated soil samples tested by direct shear test to evaluate the effect of microorganisms on shear strength of silty sandy soils. The results showed that the angle of internal friction decreased subsequently from 49.5° in untreated soil to 34.9°,36.8°,36.3°,33.5° with treatment period of two weeks, one month, two months and three months and cohesion of soil increased subsequently from 6.09 kPa for the untreated silty sand soil to 10.21,9.586,10.99,11.93 kPa for the same treatment period.


Soil improvement; Biocementation; shear strength; Microbial Carbonate Precipitation.

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