Evaluation of Shear Strength Parameters of Sandy Soils upon Microbial Treatment

Pakbaz, Mohammad Siroos; Behzadipour, Hamed; Ghezelbash, Gholam Reza

doi:10.1080/01490451.2018.1455766

Cited by 52 publications

(20 citation statements)

References 17 publications

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“…These parameters increased in the XG-R 3 solution, but to a lesser extent than in the XG-R 2 solution. This can be attributed to the deficiency of the urease enzyme in the final extract and its disproportionate amount compared to those of urea and calcium chloride in the precipitation solution, as confirmed by the test tube experiments, microscopic observations, and previous studies [31,61].…”

Section: The Effect Of the Concentration Of The Components Forming The Eicp Solutionsupporting

confidence: 71%

A Bioinspired Technique for Improving the Interaction Between Cohesive Soil and Geotextile Reinforcements

Mohammadi

Habibagahi

Hataf

2021

Int. J. of Geosynth. and Ground Eng.

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Reinforced soil structures often cannot perform properly when there is a weak interface which is not capable of mobilizing the required shear strength between fine-grained soils and the reinforcing elements. The calcium carbonate precipitation (CCP) technique adopted in this research has proved to be extremely useful in removing this deficiency. In this study, plantderived urease-induced calcium carbonate precipitation (PDUICCP) was used as a novel method to improve the performance of the interface. Instead of using commercial-grade purified urease, the extract of soybean seeds was mixed with calcium chloride and urea to prepare a precipitating solution to reduce the costs. In addition, xanthan gum was used as a benchmark to examine the efficiency of the calcium carbonate precipitation process. Modified direct shear tests were performed on the kaolin clay specimens with two different relative compactions, three concentrations of the precipitating solution, and three different geotextiles to assess the performance of the proposed method. The results revealed that the application of the proposed method improved the interfacial shear strength considerably with the interface efficiency increasing from 12 to 270% depending on the geotextile texture and roughness, the relative soil compaction, and the concentration of the precipitation solutions. The highest increase in the interfacial shear strength for all the concentrations of the precipitating solutions was obtained when the polypropylene nonwoven geotextile was used. In all the cases, increasing the relative soil compaction enhanced the interfacial shear strength and interface efficiency. The optimal concentration of the constituents in the precipitating solution was obtained when 0.64 molar (M) calcium chloride and 1 M urea were used. The results of this study can mark the beginning of a new type of geosynthetics with multiphase strength parameters after the addition of environmentally friendly materials. Moreover, they pave the way for using fine-grained soils as the bulk backfill material in reinforced soil structures where coarse-grained soil is not readily available.

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Section: The Effect Of the Concentration Of The Components Forming The Eicp Solutionsupporting

confidence: 71%

A Bioinspired Technique for Improving the Interaction Between Cohesive Soil and Geotextile Reinforcements

Mohammadi

Habibagahi

Hataf

2021

Int. J. of Geosynth. and Ground Eng.

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“…Direct utilisation of urease enzyme for inducing calcium carbonate precipitation has also been attempted in a few studies [10][11][12]. Due to the susceptibility of enzymes to environmental conditions as well as high costs, MICP has been the preferred mode of application for engineering applications [10,11,13,14]. It has also been recorded that microbially induced carbonate crystals are relatively larger than the crystals induced by an equivalent amount of enzyme offering a better alternative [12].…”

Section: Introductionmentioning

confidence: 99%

Insights into the influence of cell concentration in design and development of microbially induced calcium carbonate precipitation (MICP) process

2021

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Microbially induced calcium carbonate precipitation (MICP) process utilising the biogeochemical reactions for low energy cementation has recently emerged as a potential technology for numerous engineering applications. The design and development of an efficient MICP process depends upon several physicochemical and biological variables; amongst which the initial bacterial cell concentration is a major factor. The goal of this study is to assess the impact of initial bacterial cell concentration on ureolysis and carbonate precipitation kinetics along with its influence on the calcium carbonate crystal properties; as all these factors determine the efficacy of this process for specific engineering applications. We have also investigated the role of subsequent cell recharge in calcium carbonate precipitation kinetics for the first time. Experimental results showed that the kinetics of ureolysis and calcium carbonate precipitation are well-fitted by an exponential logistic equation for cell concentrations between optical density range of 0.1 OD to 0.4 OD. This equation is highly applicable for designing the optimal processes for microbially cemented soil stabilization applications using native or augmented bacterial cultures. Multiple recharge kinetics study revealed that the addition of fresh bacterial cells is an essential step to keep the fast rate of precipitation, as desirable in certain applications. Our results of calcium carbonate crystal morphology and mineralogy via scanning electron micrography, energy dispersive X-ray spectroscopy and X-ray diffraction analysis exhibited a notable impact of cell number and extracellular urease concentration on the properties of carbonate crystals. Lower cell numbers led to formation of larger crystals compared to high cell numbers and these crystals transform from vaterite phase to the calcite phase over time. This study has demonstrated the significance of kinetic models for designing large-scale MICP applications.

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“…3.1 Effect of soil properties I) Soil Type: To date, MICP treatment has been widely applied for different types of soils, including clay [52,53,[148][149][150], silt [150,151], residual soil [42,129,[152][153][154][155], coal ash [156,157], expansive soil [158], tabia [159], mixture of sand and clay [63,121,[160][161][162] or silt [163][164][165], sandy soil [166,167], fine sand [85,168], coarse sand [85,[168][169][170][171][172][173], calcareous sand [56,118,137,[174][175][176][177][178], gravel [150,179,180] and aggregate [116,[1...…”

Section: Strength Enhancement Of Soilmentioning

confidence: 99%

Recent development in biogeotechnology and its engineering applications

Cui

Chu

2021

Front. Struct. Civ. Eng.

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Microbial geotechnology or biogeotechnology is a new branch of geotechnical engineering. It involves the use of microbiology for traditional geotechnical applications. Many new innovative soil improvement methods have been developed in recent years based on this approach. A proper understanding of the various approaches and the performances of different methods can help researchers and engineers to develop the most appropriate geotechnical solutions. At present, most of the methods can be categorized into three major types, biocementation, bioclogging, and biogas desaturation. Similarities and differences of different approaches and their potential applications are reviewed. Factors affecting the different processes are also discussed. Examples of up-scaled model tests and pilot trials are presented to show the emerging applications. The challenges and problems of biogeotechnology are also discussed.

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Evaluation of Shear Strength Parameters of Sandy Soils upon Microbial Treatment

Cited by 52 publications

References 17 publications

A Bioinspired Technique for Improving the Interaction Between Cohesive Soil and Geotextile Reinforcements

A Bioinspired Technique for Improving the Interaction Between Cohesive Soil and Geotextile Reinforcements

Insights into the influence of cell concentration in design and development of microbially induced calcium carbonate precipitation (MICP) process

Recent development in biogeotechnology and its engineering applications

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