Experimental study on soil improvement using local microorganisms

Mohammadizadeh, Mohsen; Ajalloeian, Rassoul; Nadi, Bahram; Nezhad, Shahla Soltani

doi:10.1007/s12517-020-05450-3

Cited by 7 publications

(3 citation statements)

References 30 publications

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“…Bio-cementation involves formation of particle binding material via microbial enzymatic activities which result to improvement in the stiffness and strength of the treated soil [10]. MICP successfully increased the stiffness and strength and also reduced the water permeability of soils as reported in related literatures [11][12][13][14][15][16][17]. This study is aimed at evaluating the effect of soil microbes (B. coagulans) on the plasticity of treated lateritic soil using different Treatment Compositions.…”

Section: Introductionmentioning

confidence: 99%

Effect of Treatment Compositions on the Plasticity of Tropical Red Soil Treated with Bacillus Coagulans

Yohanna¹,

Osinubi²,

Eberemu³

et al. 2022

J. Civ. Eng. Constr.

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The study evaluated the effect of four treatment compositions on the plasticity of tropical red soil (Lateritic soil) admixed with Bacillus coagulans (B. coagulans). Samples for Atterberg limits test were prepared using four treatment compositional variables. They include 25% B. coagulans suspension and 75% cementation reagent, (25%B /75%C); 50% B. coagulans suspension and 50% cementation reagent (50% B /50%C); 75% B. coagulans suspension and 25% cementation reagent, (75%B /25% C) with the above three being in equivalent volumes of the corresponding liquid limit(LL) and 50% of the optimum moisture content (OMC) of compaction, to be both B. coagulans suspension and cementation reagent (i.e. 50% OMC B /50%OMC C) of the natural soil. Results showed that the LL for; 25%B /75% C, 50% B /50% C and 75% B /25%C generally increased from 0 up to peak values at 1.8 x 109 cells/ml and then declined at 2.4 x 109 cells/ml. In the case of samples treated with 50% OMC B/50% OMC C, the LL initially decreased from 0 up to 6.0 x 108 cells/ml and thereafter increased significantly. Plastic limit (PL), Plasticity index (PI) and Linear shrinkage (LS), recorded improvement. Regression analysis for the best treatment composition (i.e 75%B /25%C) has regression coefficient of 91.8%. Based on the four treatment compositions considered, 75%B/25%C enhanced the soil workability significantly and is suggested for geotechnical engineering applications such as road pavements that are lightly trafficked.

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Section: Introductionmentioning

confidence: 99%

Effect of Treatment Compositions on the Plasticity of Tropical Red Soil Treated with Bacillus Coagulans

Yohanna¹,

Osinubi²,

Eberemu³

et al. 2022

J. Civ. Eng. Constr.

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“…However, microbial solidi cation technology involves many elds such as biology, chemistry, and geotechnical engineering, and the microbial reaction process is complex and affected by many factors (Yi et al 2013;Shashank et al 2016); therefore, the research progress in geotechnical engineering is slow relatively. Currently, MICP technology has gradually applied and veri ed by scholars worldwide (Lee et al 2013;Mohammadizadeh et al 2020), and it has been widely researched in sand solidi cation. The main reason is that the pore size within sand particles is larger than clay, which is conducive to the adhesion of the sediment produced by microorganisms.…”

Section: Introductionmentioning

confidence: 99%

Research on Biochemical Solidification and Microstructure Characteristics of Bauxite Tailings Clay

Jiang

Wang

et al. 2022

Preprint

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Microbially induced carbonate precipitation (MICP) has an excellent consolidation effect, but the application in tailings clay is less at present. This work researched the quicklime and microbial co-curing technology (biochemical consolidation technology) to explore the consolidation characteristics and pores microstructure of tailings clay. The results show that: The optimum shear strength and compressibility of solidified soil after biochemical treatment were 30 kPa and 0.19 MPa− 1, which increased by 112.77% and decreased by 38.71% compared with quicklime treatment. The fractal dimension of surface pores was reduced after biochemical treatment and the minimum was 1.136 when the quicklime was 105g. The minimum surface porosity was 4.26%, which was reduced by 76.17% compared with quicklime treatment. The pores shape of solidified soil after biochemical treatment is more regular, and the circularity reached 65.93% in the range of 0.9-1, which is higher than 39.23% of quicklime treatment. The biochemical treatment can fill the narrow pores and make the large pore volume above 50 nm translate into a small volume. The hydrate reaction products could provide a suitable growth environment for bacteria, and the quicklime also as the source of calcium participates in the biochemical reaction. The optimum quicklime content is 105g, and excessive quicklime can increase solidified soil expansion and crack, and a high pH will inhibit bacterial activity. This work could provide a new approach to tailings reservoir stabilization and ensure the effectiveness of bauxite tailings consolidation.

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“…subtilis, Bacillus megaterium, and Bacillus lichenformis are less recognized and underexplored (Gat et al 2014;Helmi et al 2016;Moravej et al 2018;Sharma et al 2019). All of these strains are soil based; hence, if any of the urease-producing strains are present in soil, then the biostimulation can be applied (Mohammadizadeh et al 2020). Thus, it is necessary to compare and predict the calcite precipitation capabilities of bacteria strains which are commonly found in soil.…”

Section: Introductionmentioning

confidence: 99%

Simplified biogeochemical numerical model to predict pore fluid chemistry and calcite precipitation during biocementation of soil

et al. 2021

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Microbially induced calcite precipitation (MICP) technique has gained attention recently as a novel method to enhance the engineering properties of soils, especially sandy soils. However, the applicability of this method to field scale is challenging and requires understanding of the factors affecting MICP process under variable subsurface conditions. This study presents a laboratory investigation and numerical predictive model to assess pore-water chemistry and calcite precipitation during the biocementation process. Laboratory experiments were conducted to assess the microbial treatment of Narmada sand in plastic tubes using three bacterial strains and two cementation media concentrations. Calcite precipitation via ureolysis as a result of biogeochemical reactions was measured. The effects of pH and electrical conductivity (EC) on the rate of urea hydrolysis and calcite precipitation were assessed. The presence of calcite crystals was analyzed using scanning electron microscopy (SEM). The SEM images confirmed the formation of calcite at the surface and between the sand particles. A simplified numerical model was developed to estimate the rate of urea hydrolysis and their effects on the biocementation of sand. Three stages of MICP process were identified: bacterial ureolysis, dynamic equilibrium between liquid-gas interface and oversaturation of ions, and calcite precipitation. The variations of pH and EC at these three stages were modeled. The predicted pH, EC, and calcite precipitation based on the simplified model were found to be in close agreement with the experimental results. The numerical model can be used to assess and optimize the system variables for effective MICP field applications.

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Experimental study on soil improvement using local microorganisms

Cited by 7 publications

References 30 publications

Effect of Treatment Compositions on the Plasticity of Tropical Red Soil Treated with Bacillus Coagulans

Effect of Treatment Compositions on the Plasticity of Tropical Red Soil Treated with Bacillus Coagulans

Research on Biochemical Solidification and Microstructure Characteristics of Bauxite Tailings Clay

Simplified biogeochemical numerical model to predict pore fluid chemistry and calcite precipitation during biocementation of soil

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