Evaluation of the Treatment Processes for MICP-and EICP-Treated Sands
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Date
2022
Authors
Ahenkorah, I.
Rahman, M.M.
Karim, M.R.
Beecham, S.
Editors
Lemnitzer, A.
Stuedlein, A.W.
Stuedlein, A.W.
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Conference paper
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Geotechnical Special Publications, 2022 / Lemnitzer, A., Stuedlein, A.W. (ed./s), vol.2022-March, iss.GSP 331, pp.365-374
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2nd Geo Congress - Soil Improvement, Geosynthetics, and Innovative Geomaterials (20 Mar 2022 - 23 Mar 2022 : NC, Charlotte)
Abstract
Bio-cementation, notably microbial induced calcite precipitation (MICP), and Enzyme induced calcite precipitation (EICP), binds soil particles together through calcium carbonate (CACO3) precipitation (cementation). Both MICP and EICP have significant potential for many scientific and engineering applications including improvement of strength, reducing soil liquefaction potential, surface erosion control, reducing permeability, and heavy metal contaminant remediation. However, the catalytic mechanism and the precipitation of CACO3in MICP and EICP mainly depends on the source of urease enzyme and the treatment process used. This study evaluates the mechanical and microstructural behaviour of bio-cementation using the standard MICP and EICP treatment process. The results indicate that, for the same number of treatment cycles (NTC), a higher amount of precipitated CACO3was achieved for MICP than EICP which affects the strength. For similar average CACO3content (AC), the standard treatment method used in EICP produced a higher chemical efficiency (defined as the amount of CACO3precipitated relative to the quantity of urea-CaCl2used) than in MICP. The results from scanning electron microscopy (SEM) imaging shows that the morphologies of the precipitated CACO3in MICP and EICP are similar, however, a high amount of vaterite was found in EICP than MICP. The outcome of this study indicates that the standard treatment processes used in MICP and EICP may influence the chemical efficiency, the amount, distribution, and polymorph of the precipitated CACO3which may directly affect the strength.
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Copyright 2022 American Society of Civil Engineers (ASCE)
Access Condition Notes: Accepted manuscript available after 1 October 2023