Desert Aeolian Sand Cementation via Microbially Induced Carbonate Precipitation

IFCEE 2021 ◽  
2021 ◽  
Author(s):  
Xichen Xu ◽  
Hongtao Wang ◽  
Wenbin Lin ◽  
Xiaohui Cheng ◽  
Hongxian Guo
Keyword(s):  
Carbonate Precipitation ◽  
Aeolian Sand ◽  
Microbially Induced Carbonate Precipitation

scholarly journals The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charalampos Konstantinou ◽  
Yuze Wang ◽  
Giovanna Biscontin ◽  
Kenichi Soga
Keyword(s):  
Calcium Carbonate ◽  
Calcium Chloride ◽  
Urease Activity ◽  
Coarse Sand ◽  
Carbonate Precipitation ◽  
Population Densities ◽  
Carbonate Cements ◽  
Microbially Induced Carbonate Precipitation

AbstractProtocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

scholarly journals Microbially-induced Carbonate Precipitation for Immobilization of Toxic Metals

2016 ◽  
pp. 79-108 ◽  
Author(s):  
Deepika Kumari ◽  
Xin-Yi Qian ◽  
Xiangliang Pan ◽  
Varenyam Achal ◽  
Qianwei Li ◽  
...  
Keyword(s):  
Toxic Metals ◽  
Carbonate Precipitation ◽  
Microbially Induced Carbonate Precipitation

Tensile strength of sands treated with microbially induced carbonate precipitation

2020 ◽  
Vol 57 (10) ◽  
pp. 1611-1616 ◽  
Author(s):  
Ashkan Nafisi ◽  
Douglas Mocelin ◽  
Brina M. Montoya ◽  
Shane Underwood
Keyword(s):  
Tensile Strength ◽  
Large Earthquake ◽  
Carbonate Precipitation ◽  
Direct Tension ◽  
Sem Images ◽  
Cemented Soil ◽  
Tension Tests ◽  
Deformational Behavior ◽  
Microbially Induced Carbonate Precipitation ◽  
Sand Type

During large earthquake events where bending moments within soil cements are induced, the tensile strength of cemented soil may govern the deformational behavior of improved ground. Several studies have been conducted to assess the tensile strength of artificially cemented sands that use Portland cement or gypsum; however, the tensile strength of microbially induced carbonate precipitation (MICP)-treated sands with various particle sizes measured through direct tension tests has not been evaluated. MICP is a biomediated improvement technique that binds soil particles through carbonate precipitation. In this study, the tensile strength of nine specimens were measured by conducting direct tension tests. Three types of sand (coarse, medium, and fine) were cemented to reach a heavy level of cementation (e.g., shear wave velocity of ∼900 m/s or higher). The results show that the tensile strength varies between 210 and 710 kPa depending on sand type and mass of carbonate. Unconfined compressive strength (UCS) tests were performed for each sand type to assess the ratio between tensile strength and UCS in MICP-treated sands. Scanning electron microscopy (SEM) images and surface energy measurements were used to determine the predominant failure mode at particle contacts under tensile loading condition.

Strength and Permeability of Bentonite-Assisted Biocemented Coarse Sand

2020 ◽  
Author(s):  
Guoliang Ma ◽  
Xiang He ◽  
Xiang Jiang ◽  
Hanlong Liu ◽  
Jian Chu ◽  
...  
Keyword(s):  
Unconfined Compressive Strength ◽  
Volume Fraction ◽  
Coarse Sand ◽  
Effective Concentration ◽  
Carbonate Precipitation ◽  
Natural Clay ◽  
High Concentration ◽  
Strength Enhancement ◽  
Microbially Induced Carbonate Precipitation ◽  
Clay Aggregates

To effectively stabilize coarse sand, bentonite was introduced in microbially induced carbonate precipitation (MICP) grouting. Varying concentrations (0 g/L, 20 g/L, 40 g/L and 80 g/L) of bentonite were added to bacterial suspensions (BSs), which were magnetically stirred to form bacterial-bentonite suspensions (BBSs). Then, coarse sand specimens were treated with BBSs and cementation solutions (CSs) to different cementation levels. The results showed that the addition of bentonite could increase the volume fractions of the precipitates consisting of calcium carbonate (CaCO3) and bentonite. The permeability decreased exponentially as the volume fraction of precipitates increased. As the active precipitates increased when a lower concentration (e.g., 20 g/L) of bentonite was added to the MICP grouting, the unconfined compressive strength (UCS) was substantially improved. However, detrimental effects were observed for specimens treated with a high concentration of bentonite. These results indicate that the effective concentration of natural clay aggregates used in MICP grouting was different for different engineering applications, e.g., seepage control and strength enhancement. The current work provides an encouraging method of improving the MICP technique.

scholarly journals Improving the strength of sandy soils via ureolytic CaCO<sub>3</sub> solidification by <i>Sporosarcina ureae</i>

2018 ◽  
Vol 15 (14) ◽  
pp. 4367-4380 ◽  
Author(s):  
Justin Michael Whitaker ◽  
Sai Vanapalli ◽  
Danielle Fortin
Keyword(s):  
Shear Strength ◽  
Acid Rain ◽  
Climatic Conditions ◽  
Carbonate Precipitation ◽  
Biogeochemical Process ◽  
Climate Conditions ◽  
Sporosarcina Ureae ◽  
Microbially Induced Carbonate Precipitation ◽  
Environmental Durability ◽  
Hydrolysis Of

Abstract. “Microbially induced carbonate precipitation” (MICP) is a biogeochemical process that can be applied to strengthen materials. The hydrolysis of urea by microbial catalysis to form carbonate is a commonly studied example of MICP. In this study, Sporosarcina ureae, a ureolytic organism, was compared to other ureolytic and non-ureolytic organisms of Bacillus and Sporosarcina genera in the assessment of its ability to produce carbonates by ureolytic MICP for ground reinforcement. It was found that S. ureae grew optimally in alkaline (pH ∼ 9.0) conditions which favoured MICP and could degrade urea (units U mL−1 represent µmol min−1 mL OD600) at levels (30.28 U mL−1) similar to S. pasteurii (32.76 U mL−1), the model ureolytic MICP organism. When cells of S. ureae were concentrated (OD600 ∼ 15–20) and mixed with cementation medium containing 0.5 M calcium chloride (CaCl2) and urea into a model sand, repeated treatments (3 × 24 h) were able to improve the confined direct shear strength of samples from 15.77 kPa to as much as 135.80 kPa. This was more than any other organism observed in the study. Imaging of the reinforced samples with scanning electron microscopy and energy-dispersive spectroscopy confirmed the successful precipitation of calcium carbonate (CaCO3) across sand particles by S. ureae. Treated samples were also tested experimentally according to model North American climatic conditions to understand the environmental durability of MICP. No statistically significant (p < 0.05, n= 3) difference in strength was observed for samples that underwent freeze–thaw cycling or flood-like simulations. However, shear strength of samples following acid rain simulations fell to 29.2 % of control MICP samples. Overall, the species S. ureae was found to be an excellent organism for MICP by ureolysis to achieve ground strengthening. However, the feasibility of MICP as a durable reinforcement technique is limited by specific climate conditions (i.e. acid rain).

Effect of Cement Type and Air-Entraining Agent on Microbially Induced Carbonate Precipitation in Cement Paste

2013 ◽  
Vol 816-817 ◽  
pp. 758-761
Author(s):  
Xiao Lu Yuan ◽  
Shi Hua Zhou ◽  
Wei Min Hu ◽  
Sen Yao Tan ◽  
Deng Pan
Keyword(s):  
Growth Rate ◽  
Compressive Strength ◽  
Cement Paste ◽  
Carbonate Precipitation ◽  
Cement Type ◽  
Cement Pastes ◽  
Sulphoaluminate Cement ◽  
Microbially Induced Carbonate Precipitation

The effect of cement type and the air-entraining agent on microbially induced carbonate precipitation in cement paste has been studied. Results indicate that after biodeposition treatment, Sulphoaluminate cement paste behaved with a higher growth rate of compressive strength than OPC paste. Incorporation of air-entraining agent increased the growth rate of compressive strength of sulphoaluminate cement paste. Calcite was formed through microbially induced carbonate precipitation in cement pastes. Sulphoaluminate cement paste achieved a larger amount of calcite than OPC paste.

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