Characteristics of MICP- and EICP-treated sands in simple shear conditions: a benchmarking with the critical state of untreated sand

Ahenkorah, Isaac; Rahman, M.F.; Karim, Rajibul; Beecham, Simon

doi:10.1680/jgeot.22.00329

Cited by 6 publications

(2 citation statements)

References 59 publications

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“…As illustrated in Fig. 2, the mechanical characteristics of MICP-treated soil undergo the following changes (Cui et al, 2021;Nafisi et al, 2019;Nafisi et al, 2021;Ahenkorah et al, 2023):…”

Section: Mechanical Features Of the Micp-treated Specimensmentioning

confidence: 99%

Statistical damage constitutive model of MICP-treated specimens based on Lognormal Distribution

Jiang,

Huang,

et al. 2024

Preprint

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Microbial-induced carbonate precipitation (MICP) technique have the potential to be an eco-friendly and sustainable solution for engineering problems that has presented promise in various geotechnical applications. Despite the extensive amounts of studies about the MICP technique has been conducted recently, there are few studies on the constitutive model of MICP-treated specimens. In this study, the statistical damage constitutive model of MICP-treated specimens was established based on the statistical theory and damage mechanics theory. The model assumed that the microelement strength of bio-cemented sand obeys the log-normal random distribution and the D-P criterion. The parameters S0 and F0 in the constitutive model were determined and the physical significance of parameters were discussed accordingly. The reasonableness of the proposed model were verified by comparing the theoretical results and the experimental results. The evolution of the damage variable (D), parameter S0 and parameter F0 with different calcium carbonate content (CCC) were analyzed. The statistical damage models based on log-normal distributions was then compared with that based on Weibull distributions. The results show that the parameter F0 and S0 can reflect the limiting strength and brittleness of MICP-treated specimens, respectively. The damage rate accelerates with increase in cementation level, leading to larger damage values. The damage variables eventually reaches a stable value as the axial deformation increases. The proposed model can reflect the strain softening and strain hardening phenomena well, which can also represent the shear expansion and shear contraction characteristics of the volume strain curve. Overall, the research in this study provide some theoretical support for the engineering application of MICP-treated specimens.

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“…As illustrated in Fig. 2, the mechanical characteristics of MICP-treated soil undergo the following changes (Cui et al, 2021;Nafisi et al, 2019;Nafisi et al, 2021;Ahenkorah et al, 2023):…”

Section: Mechanical Features Of the Micp-treated Specimensmentioning

confidence: 99%

Statistical damage constitutive model of MICP-treated specimens based on Lognormal Distribution

Jiang,

Huang,

et al. 2024

Preprint

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“…They found that, compared with the untreated sand, all EICP treatment methods significantly increase the erosion resistance of treated sand, and 1.0 M cementing solution is a more feasible option to achieve the optimal erosion resistance. Ahenkorah et al [ 22 ] conducted a direct simple shear (DSS) test and studied the mechanical properties of EICP-treated sand and untreated sand under critical conditions. Based on their study, compared with the treated samples under similar initial conditions, the EICP-treated samples have a higher shear strength, and the final state of the treated sand tends to have a lower percentage of voids than the untreated critical state sand.…”

Section: Introductionmentioning

confidence: 99%

Study on the Mechanical Properties of Crack Mortar Repaired by Enzyme-Induced Calcium Carbonate Precipitation (EICP)

Li,

Yan,

Liu

et al. 2024

Materials

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As an emerging repair method, the enzyme-induced calcium carbonate precipitation (EICP) technique has the advantages of being highly economical, eco-friendly, and durable. The optimal repair conditions were obtained by taking cement mortar as the research object, adding two types of filling medium, using three EICP-based repair methods to repair the cement mortar with different crack widths, and combining ultrasonic testing and strength testing to evaluate the mechanical properties and repair effects of the repair mortar. The microscopic structure of the mortar was established using mesoscopic and microscopic tests (XRD, SEM, and EDS), thereby revealing the mechanism of repair based on EICP. The test results show that, when quartz sand is used as the repair medium, more calcium carbonate adheres to the cross-section of test samples, and it has a better repair effect. Moreover, the repair effect of the injection method is significantly higher than those of the perfusion and immersion methods, and the ultrasonic wave transit time decreases by 1.22% on average. Based on the combination of quartz sand and EICP repair methods, the calcium carbonate precipitated among the sand granules contributes to a binding effect that strengthens the cohesive force among the sand granules.

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Cyclic liquefaction resistance of MICP- and EICP-treated sand in simple shear conditions: a benchmarking with the critical state of untreated sand

Ahenkorah,

Rahman,

Karim

et al. 2024

Acta Geotech.

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In the present study, the undrained cyclic behaviour of biotreated sands using microbial and enzyme-induced carbonate precipitation was investigated for a wide range of initial void ratio after consolidation ($$e_{0}$$ e 0 ), initial effective normal stress ($$\sigma^{\prime }_{{{\text{N}}_{0} }}$$ σ N 0 ′ ) and calcium carbonate content (CC) under direct simple shear (DSS) testing conditions. The critical state soil mechanics framework for untreated sand was first established using a series of drained and undrained (constant volume) tests, which served as a benchmark for evaluating the undrained cyclic liquefaction behaviour of untreated and biotreated sands. The results indicated that the modified initial state parameter ($$\psi_{{{\text{m}}_{{0}} }}$$ ψ m 0 ) in DSS condition showed a good correlation with instability states and phase transformation under monotonic shearing. In undrained cyclic DSS loading condition, samples displayed cyclic mobility indicated by an abrupt accumulation of large strain or $$\sigma^{\prime }_{{N_{0} }}$$ σ N 0 ′ transiently reaching zero or a sudden build-up of excess pore water pressure. The linkage between static and cyclic liquefaction was established for untreated and biotreated sand specimens based on the equivalence of characteristic soil states. The number of cycles before liquefaction (NL) for the biotreated sand specimens was mainly controlled by the cyclic stress ratio, $$e_{0}$$ e 0 , $$\sigma^{\prime }_{{{\text{N}}_{{0}} }}$$ σ N 0 ′ and CC. For a similar initial state prior to undrained cyclic loading, the biotreated specimens required a larger NL compared to the untreated sand. The cyclic resistance ratio at NL = 15 (CRR15) increased with decreasing $$\psi_{{{\text{m}}_{{0}} }}$$ ψ m 0 for the untreated sand, while the CRR15 for biotreated sand increased with increasing CC and decreasing $$\sigma^{\prime }_{{N_{0} }}$$ σ N 0 ′ .

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Characteristics of MICP- and EICP-treated sands in simple shear conditions: a benchmarking with the critical state of untreated sand

Cited by 6 publications

References 59 publications

Statistical damage constitutive model of MICP-treated specimens based on Lognormal Distribution

Statistical damage constitutive model of MICP-treated specimens based on Lognormal Distribution

Study on the Mechanical Properties of Crack Mortar Repaired by Enzyme-Induced Calcium Carbonate Precipitation (EICP)

Cyclic liquefaction resistance of MICP- and EICP-treated sand in simple shear conditions: a benchmarking with the critical state of untreated sand

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