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Effect of Microbial Induced Calcium Carbonate Precipitation on Compressibility and Hydraulic Conductivity of Fly Ash
The morphology and chemical composition of fly ash render the material unique in comparison to natural sediments. Fly ash deposited in ash ponds can possess a loose, saturated, and contractive structure with a tendency to collapse under induced shear stresses. Compressibility and hydraulic conductivity are the two main parameters affecting the stability of this material in ash ponds. Microbial induced calcium carbonate precipitation (MICP) is a novel approach, which has been widely studied to improve engineering properties of soils. In this study, the MICP treatment process is applied to a Class-F fly ash material to assess its effect on the two mentioned parameters. Modified odometer testing was developed with the ability to inject the treatment solution, measure the induced pressure during injection, and monitor the shear wave velocity of the test specimens. The specimens were successfully treated using MICP, reaching predetermined target shear wave velocities. The results of compressibility on treated and untreated specimens indicate that MICP decreases the compressibility of the studied material while the hydraulic conductivity decreased by only one order of magnitude or less. The shear wave velocity of the treated and untreated specimens converged to the same value while the vertical applied stress increased, indicating the calcium carbonate bond breakage between particles.
Effect of Microbial Induced Calcium Carbonate Precipitation on Compressibility and Hydraulic Conductivity of Fly Ash
The morphology and chemical composition of fly ash render the material unique in comparison to natural sediments. Fly ash deposited in ash ponds can possess a loose, saturated, and contractive structure with a tendency to collapse under induced shear stresses. Compressibility and hydraulic conductivity are the two main parameters affecting the stability of this material in ash ponds. Microbial induced calcium carbonate precipitation (MICP) is a novel approach, which has been widely studied to improve engineering properties of soils. In this study, the MICP treatment process is applied to a Class-F fly ash material to assess its effect on the two mentioned parameters. Modified odometer testing was developed with the ability to inject the treatment solution, measure the induced pressure during injection, and monitor the shear wave velocity of the test specimens. The specimens were successfully treated using MICP, reaching predetermined target shear wave velocities. The results of compressibility on treated and untreated specimens indicate that MICP decreases the compressibility of the studied material while the hydraulic conductivity decreased by only one order of magnitude or less. The shear wave velocity of the treated and untreated specimens converged to the same value while the vertical applied stress increased, indicating the calcium carbonate bond breakage between particles.
Effect of Microbial Induced Calcium Carbonate Precipitation on Compressibility and Hydraulic Conductivity of Fly Ash
Safavizadeh, Shahin (author) / Montoya, Brina M. (author) / Gabr, Mohammed A. (author)
IFCEE 2018 ; 2018 ; Orlando, Florida
IFCEE 2018 ; 69-79
2018-06-06
Conference paper
Electronic Resource
English
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