Baseline Investigation on Enzyme-Induced Calcium Carbonate Precipitation

Almajed, Abdullah; Tirkolaei, Hamed Khodadadi; Kavazanjian, Edward

doi:10.1061/(asce)gt.1943-5606.0001973

Cited by 198 publications

(98 citation statements)

References 21 publications

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“…Almajed et al [8] conducted a study to optimize the EICP solution to maximize the calcium carbonate precipitation. According to Almajed et al [8], 37 different solutions of EICP were investigated inside 50-mL test tubes containing 20 mL of EICP solution without soil. The urea concentration was varied from 0.25 to 1.5 M, the ratio of CaCl2 to urea was varied from 1:1 to 1:1.75, and the enzyme concentration was varied from 1 to 6 g/L.…”

Section: Prior Studies On Soil Improvement Via Eicpmentioning

confidence: 99%

“…Important finding of this study is that the optimum ratio of the urea to calcium concentration was found to be 1:1.5. In the same study, Almajed et al [8] used the optimized solution (0.67 M calcium chloride, 1 M urea, and 3 g/L urease enzyme) to treat eight sand columns with two different methods of preparation (mix-and-compact and percolation methods). Four samples were prepared by percolation where they added only one pore volume of EICP solution from the top of the sample and then let the sample cure for 7 days with multiple cycles of treatment (maximum four cycles of treatment).…”

Section: Prior Studies On Soil Improvement Via Eicpmentioning

confidence: 99%

“…The other four samples were treated by mix and compact, where dry sand was mixed with same volume of EICP solution used for the percolation test and with the same regime of percolation treatment after initial mix and compact. Almajed et al [8] found out that samples treated with mix and compact did not have sufficient strength to measure the unconfined compressive strength. On the other hand, 1.2 MPa was achieved after four cycles and 99 kPa after one cycle of treatment for samples treated with percolation method.…”

Section: Prior Studies On Soil Improvement Via Eicpmentioning

confidence: 99%

“…Study was conducted to evaluate the possibility of using mix-and-compact technique to improve the soil without subsequent cycles of treatment. In this study, three EICP solutions were investigated with three levels of urea concentrations 1.0 M, 2.0 M and 3.0 M. The urea to calcium chloride ratio was fixed at 1:0.67 according to the findings of Almajed et al [8]. The unconfined strength of the treated samples as well as the calcium carbonate precipitant concentration were investigated.…”

Section: Objectivesmentioning

confidence: 99%

“…Table 1 shows a summary of three EICP cementation solutions used with the constituents for each EICP solution. 1M solution is the solution that recommended by Almajed et al [8]. The other two solutions are basically two and three times the concentration of each constituent of the 1M cementing solution.…”

Section: Testing Programmentioning

confidence: 99%

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One Phase Soil Bio-Cementation with EICP-Soil Mixing

Rohy¹,

Arab²,

Zeiada³

et al. 2019

World Congress on Civil, Structural, and Environmental Engineering

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Soil improvement techniques of granular soils via Enzyme Induced Calcite Precipitation (EICP) have attracted an increasing attention as bio-based ground improvement technique. This technique uses biogeochemical reactions to precipitate calcium carbonate (CaCO3). Calcium carbonate precipitate introduced into soil pores help bind soil particles and result in increased soil shear strength. The multiple-phase injection and percolation methods are currently adopted for EICP treatment to reach the desired soil shear strength. However, this method is rather complex and not feasible for practical applications. In this study, one-phase low-pH all-in-one solution (i.e. a mixture of urease enzyme, urea, CaCl2 and organic stabilizer) mixed with sand soil to enhance the soil shear strength has been proposed. Three different EICP cementing solutions have been investigating. A key factor that facilitated this approach is decrease the pH of the cementing solution to facilitate longer period and slower reaction of the precipitation of calcium. Unconfined compressive strength of 3.0 MPa was achieved by mixing cementing solution with soil without multiple treatment cycles.

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Section: Prior Studies On Soil Improvement Via Eicpmentioning

confidence: 99%

Section: Prior Studies On Soil Improvement Via Eicpmentioning

confidence: 99%

Section: Prior Studies On Soil Improvement Via Eicpmentioning

confidence: 99%

Section: Objectivesmentioning

confidence: 99%

Section: Testing Programmentioning

confidence: 99%

See 3 more Smart Citations

One Phase Soil Bio-Cementation with EICP-Soil Mixing

Rohy¹,

Arab²,

Zeiada³

et al. 2019

World Congress on Civil, Structural, and Environmental Engineering

Self Cite

View full text Add to dashboard Cite

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Calcium carbonate precipitation by cave bacteria isolated from Kashmir Cave, Khyber Pakhtunkhwa, Pakistan

Jan

Zada

Rafiq

et al. 2022

Microscopy Res & Technique

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The participation of numerous physicochemical and biological functions maintains the evolution and expansion of the remarkable nature. Due to its vast applicability in several engineering disciplines, naturally occurring bio-mineralization or microbially induced calcium carbonate (MICP) precipitation is attracting more interest. Cave bacteria contribute to the precipitation of calcium carbonate (CaCO 3 ). In the present study, soil sediments were collected from Kashmir cave, KPK, Pakistan, and plated on B4 specific nutrients limited medium for bacterial isolation and the viable bacterial count was calculated. Three bacterial strains named were capable of precipitating CaCO 3 . These bacterial isolates were identified through 16S rRNA gene sequencing and strain GSN-11 was identified as Bacillus toyonensis, TFSN-14 as Paracoccus limosus and TFSN-15 as Brevundimonas diminuta. Enhanced CaCO 3 precipitation potential of these bacteria strains was observed at 25 C and pH 5. The precipitated CaCO 3 was confirmed by scanning electron microscopy, X-ray powder diffraction, and Fourier transform infra-red spectroscopy. The findings showed that the precipitates were dominated by calcite, aragonite, and nanosize vaterite. Current research suggests that precipitation of CaCO 3 by proteolytic cave bacteria is widespread in Kashmir cave and these bacterial communities can actively contribute to the formation of CaCO 3 by enhancing the pH of the microenvironment. Research Highlights• Kashmir cave inhabit potentially active bacteria in terms of biogeochemical processes.• Cave bacteria significantly precipitated CaCO 3 .• Calcite, aragonite, and nanosize vaterite were dominant in precipitates.

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