scholarly journals Engineering Properties of Sandy soil Improvement with Bacillus Simplex

2021 ◽  
Author(s):  
Baki Bagriacik ◽  
Zahrettin Kabir Sani ◽  
Fatima Masume Uslu ◽  
Esra Sunduz Yigittekin ◽  
Sadik Dincer
Keyword(s):  
Calcium Carbonate ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Calcium Carbonate Precipitation ◽  
Weak Soil ◽  
Pathogenic Organism ◽  
Direct Shear Tests ◽  
Bacillus Simplex ◽  
Soil Stabilisation ◽  
Cement Stabilization

Abstract Purpose: Stabilization of weak soil can be achieved through different methods, some of which include: jet column, cement stabilization and fly ash stabilization. Unfortunately, the use of the aforementioned methods of soil improvement affects the environment negatively thereby leading to environmental degradation. With the aforesaid impediment in mind, the need for devising methods of weak soil improvement becomes pertinent. Methods: Bacillus sp. - a non-pathogenic organism found abundantly in soil - was investigated in this study as a potential agent of soil improvement. The usability of Bacillus sp. in soil improvement was investigated with direct shear tests and permeability tests under optimum conditions in this study.Result: Time-dependent study on the effect of the ureolytic bacteria Bacillus simplex induced calcium carbonate precipitation shows reduction in permeability and increase in the strength of the soil under study. On exhaustion of the available nutrients in the soil however, the strength of the soil is not negatively impacted.Conclusion: Microbially induced calcium precipitation by Bacillus sp. is effective in soil improvement as such it may serve as substitute for conventional soil stabilisation techniques. The ability of the bacteria to precipitate calcium carbonate in the soil leads to reduction in the permeability and increase in the shear strength of the soil.

scholarly journals An experimental approach to microbial carbonate precipitation in improving the engineering properties of sandy soils

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Baki Bagriacik ◽  
Zahraddeen Kabir Sani ◽  
Fatima Masume Uslu ◽  
Esra Sunduz Yigittekin ◽  
Sadik Dincer
Keyword(s):  
Calcium Carbonate ◽  
Soil Stabilization ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Carbonate Precipitation ◽  
Bacillus Sp ◽  
Calcium Carbonate Precipitation ◽  
Weak Soil ◽  
Direct Shear Tests ◽  
Microbial Carbonate Precipitation

Abstract Purpose Stabilization of weak soil can be achieved through different methods, some of which include jet column, cement stabilization and fly ash stabilization. Unfortunately, the use of the aforementioned methods of soil improvement affects the environment negatively thereby leading to environmental degradation. With the aforesaid impediment in mind, the need for devising methods of weak soil improvement becomes pertinent. Methods Bacillus sp. — a non-pathogenic organism found abundantly in soil — was investigated in this study as a potential agent of soil improvement. The usability of Bacillus sp. in soil improvement was investigated with direct shear tests and permeability tests under optimum conditions in this study. Result Time-dependent study on the effect of the ureolytic bacteria Bacillus sp.-induced calcium carbonate precipitation shows reduction in permeability and increase in the strength of the soil under study. On exhaustion of the available nutrients in the soil, however, the strength of the soil is not negatively impacted. Conclusion Microbially induced calcium precipitation by Bacillus sp. is effective in soil improvement as such it may serve as substitute for conventional soil stabilization techniques. The ability of the bacteria to precipitate calcium carbonate in the soil leads to reduction in the permeability and increase in the shear strength of the soil.

scholarly journals The investigation of microbial induced calcium carbonate precipitation for soil improvement

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Jamie Haystead ◽  
Martyn Dade-Robertson ◽  
Thora Arnardottir ◽  
Beate Christgen ◽  
Meng Zhang
Keyword(s):  
Experimental Data ◽  
Calcium Carbonate ◽  
Computational Models ◽  
Soil Improvement ◽  
Gas Production ◽  
Sand Particle ◽  
Growth Media ◽  
Growth Stages ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation

Weak and unstable soils can limit the building of new infrastructure. Current soil strengthening techniques such as chemical grouting have detrimental effects on the environment from greenhouse gas production, soil pH modification and groundwater contamination. Microbial-induced calcium carbonate precipitation (MICCP) is a technique that utilises the ability of bacteria to precipitate calcium carbonate, which can be used for a variety of applications including binding adjacent soil particles and filling the pore spaces of soils to increase their mechanical properties. A commonly used bacterium is Sporosarcina pasteurii. A range of factors influences MICCP which presents challenges with process optimisation. Some studies have made use of computational models to predict biocementation at a larger scale, however aspects of models are based on assumption of conditions instead of experimental data. An aim of this project is to investigate urease activity in S. pasteurii by comparing different growth media, growth stages, pH and temperatures. Ureolysis kinetics of S. pasteurii will be investigated at different urea and calcium chloride concentrations in liquid media. Finally, the biocementation of S. pasteurii in sand syringe setups will also be investigated to compare the effects of changing influencing factors such as growth stage and cell concentration of S. pasteurii, sand particle size, cementation media concentration, duration between cementation media applications and overall number of cementation treatments. Experimental work will be particularly focused towards gaps in the experimental data used in computational models, to help improve these models and bring MICCP biocementation closer to commercial use.

Investigating challenges of in situ delivery of microbial-induced calcium carbonate precipitation (MICP) in fine-grain sands and silty sand

2019 ◽  
Vol 56 (12) ◽  
pp. 1889-1900 ◽  
Author(s):  
Atefeh Zamani ◽  
Brina M. Montoya ◽  
Mohammed A. Gabr
Keyword(s):  
Numerical Modeling ◽  
Calcium Carbonate ◽  
Hydraulic Conductivity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rate Of Change ◽  
Silty Sand ◽  
Engineering Properties ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation

Microbial-induced calcium carbonate precipitation (MICP) is a sustainable soil improvement method with the potential for improving the engineering properties of sand and silty soils and therefore their resistance to liquefaction-inducing events. Work presented herein experimentally investigates the changes in hydraulic conductivity of fine sands and silty sands as a result of MICP treatment. In addition, numerical modeling is conducted to assess the changes in allowable injection rate and radius of influence for the delivery of the MICP process at the field scale. The hydraulic conductivity of Nevada sand and silty sand with 15% fines content decreased through MICP application with the trend of reduction being similar for both soils. Numerical modeling results show that with the progress of the MICP process, injection rates can be increased for Nevada sand, but remain unchanged for Nevada sand with 15% silt content (after MICP treatment up to a shear wave velocity about 400 m/s.) The presence of fines by itself leads to generation of higher levels of pore-water pressure during the injection process, which necessitates higher strength improvement to prevent development of excessive plastic strains. Therefore, improvement in shear strength and stiffness relative to the magnitude of the hydraulic conductivity level and its rate of change during the MICP process is a key parameter in determining the radius of treatment.

Desiccation Induced Shrinkage of Compacted Lateritic Soil Treated via Enzymatic Induced Calcium Carbonate Precipitation Technique

2021 ◽  
Vol 1030 ◽  
pp. 110-123
Author(s):  
Muttaqa Uba Zango ◽  
Khairul Anuar Kassim ◽  
Abubakar Sadiq Muhammed ◽  
Kamarudin Ahmad ◽  
Jodin Makinda
Keyword(s):  
Calcium Carbonate ◽  
Shrinkage Strain ◽  
Engineering Properties ◽  
Volumetric Shrinkage ◽  
Natural Soil ◽  
Residual Soil ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
British Standard ◽  
Volumetric Shrinkage Strain

Exploring the biological process to enhance the engineering properties of soil have received enormous recognition in recent years. Enzymatic induced calcium carbonate precipitation (EICP) is one of the bio-inspired methods of utilizing free urease to precipitates calcite from urea and calcium ions for bettering the geotechnical properties of poor soils. In this research, the EICP technique was used to improve the volumetric shrinkage strain of compacted soil liner. In this work, the residual soil was treated with various concentrations of cementations ranging from 0.25 to 1.0 M, and the soil was subjected to Atterberg limit tests, compaction test using British standard light (BSL) and reduced British standard light (RBSL) and desiccation drying volumetric shrinkage strain test. The study's findings revealed a remarkable improvement in the liquid limit and plasticity index of the treated residual soils compared to natural soil. It was also found that the volumetric shrinkage strain of the treated soil reduces progressively from 5.24% of natural to 1.49% at 1.0 M cementation solution when the soils were prepared at 0% OMC and BSL compaction effort. Based on the consideration of permissible VSS of less than 4%, the best treatment was obtained at 1.0 M for both BSL and RBSL prepared samples. Similarly, the best compaction plane is found in the treated with 1.0 M cementation solution.

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