Abstract
A recently developing bacteria based soil-stabilization technique inspired from microbially impelled calcite precipitation phenomena is verified for geo-technical applications. This phenomena make use of the metabolic mechanics of microorganisms to produce calcite precipitation all through soil matrix enhancing the soil’s engineering properties. Unconfined compressive strength (UCS) and soil hydraulic conductivity or permeability is evaluated to validate the formation of mineral precipitates between and around soil grains. Due to metabolic process of bacteria calcite minerals are generated binding the soil particles together reducing the voids volume and diameter subsequently a dense microstructure is formed. This improvement of soil homogeneity reduces the hydraulic conductivity and increase the unconfined compression strength of bacteria-treated soil samples. From the results of experimental investigations it is confirmed that mineral precipitation biologically proves to be an effective and efficient method of soil stabilization in increasing the stiffness and permeability of soil samples considered for study.
Highlights
In the present study the two soil samples with fine and coarse particle size distribution were treated with Sporosarcina pasteurii bacteria to stimulate mineral precipitation by producing urease enzyme which catalyzes the urea hydrolysis forming CO2 and NH3
The high viscous bacterial suspension cannot pass through the sample so that effective bio-mineralization is prevented from happening due to restricted spaces between soil grains
Bio-mediated sandy soil stabilization using urease enzymatic calcite precipitation is a sustainable solution to solidify sand using the mechanism of bio-mineralization
Summary
In the present study the two soil samples with fine and coarse particle size distribution were treated with Sporosarcina pasteurii bacteria to stimulate mineral precipitation by producing urease enzyme which catalyzes the urea hydrolysis forming CO2 and NH3. Due to high pH environment of produced ammonia, the soil matrix nearby converts to extremely alkaline and calcium ion from calcium nutrient source reacts with CO2 to form calcium carbonate minerals which will binds the soil particles
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