Effect of Biologically Induced Cementation via Ureolysis in Stabilization of Silty Soil
2022
Mukherjee, Siddhartha | Sahu, Ramendu Bikas | Mukherjee, Joydeep
As a potential eco-friendly and sustainable method of ground improvement, microbiologically induced carbonate precipitation (MICP) has drawn considerable attention from researchers over the last few years. In this study, Bacillus megaterium, a nonpathogenic microorganism has been used for MICP treatment to enhance the shear strength of the weak silty soil. In the 1st stage of the experiment, bacterial cell density, the concentration of cementation solution, and the relative density of soil were considered as treatment variables. The optimum conditions were derived based on Unconfined Compressive Strength (UCS) and calcium carbonate content of soil samples cured for 7 days and were then applied to a study of ‘curing time’ (0, 4, 7, 15, 21, 30, and 60 days) as a variable, with calcium carbonate content and triaxial tests as measures of optimum curing time. Maximum strength gain for treated samples was observed after 21 days of curing. Beyond this period some strength loss, in the range of 20%, was observed due to the dissolution of precipitated calcite indicating the effectiveness of B. megaterium in the strength improvement of silty soil. SEM and EDS analyses confirmed the formation of CaCO₃ and justified the experimental findings.
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