News from My Research Group

News from My Research Group

  • Wind Erosion Mitigation Using Microbial-Induced Carbonate Precipitation

    Our paper titled “Wind erosion mitigation using microbial-induced carbonate precipitation” has been published in the Journal of Geotechnical and Geoenvironmental Engineering.

    CITATION

    Gao K., Bick P., Suleiman M.T., Xiwei Li, Helm J., Brown D.G., and Zouari N. 2023. “Wind Erosion Mitigation Using Microbial Induced Carbonate Precipitation (MICP)” Journal of Geotechnical and Geoenvironmental Engineering. 149(8):04023053.

    ABSTRACT

    The wind erosion resistance of the microbial-induced carbonate precipitation (MICP)-treated soil was investigated in this study using wind tunnel experiments. A wind tunnel was calibrated to simulate the atmospheric boundary layer (ABL). The erosion modes of the soil samples with increasing and cyclic wind loading were analyzed using digital imaging techniques. The calcium carbonate content and its uniformity in treated soils were determined using an atomic absorption spectrometer. The effect of soil relative density, soil type, MICP treatment protocol, and wind loads on wind erosion mitigation was evaluated. Based on the testing conditions, a MICP treatment protocol using 0.25 pore volume of bacteria medium (Sporosarcina pasteurii, ATCC 11859) followed by 0.25 pore volume of 0.3 M cementation medium was determined as the optimal treatment for increasing wind load resistance. A calcium content of 0.28% for the soil surface layer was the minimum calcium carbonate content necessary to mitigate wind erosion for the increasing wind loading condition. For the cyclic wind loading condition, a MICP treatment protocol to achieve a minimum calcium carbonate content of 0.68% was determined as the optimum treatment protocol.

  • Shear and Tensile Strength Measurement of CaCO3 Cemented Bond Between Glass Beads Treated by Microbially Induced Calcite Precipitation (MICP)

    Our paper titled “Shear and Tensile Strength Measurement of CaCO3 Cemented Bond Between Glass Beads Treated by Microbially Induced Calcite Precipitation (MICP)” has been accepted for publication in the Journal of Geotechnical and Geoenvironmental Engineering.

    Citation

    Gao K., Lin H., Suleiman M.T., Bick P., Babuska T., Xiwei Li, Helm J., Brown D.G., and Zouari N. 2023. “Shear and Tensile Strength Measurements of CaCO3 Cemented Bonds Between Glass Beads Treated by Microbially Induced Carbonate Precipitation (MICP)” Journal of Geotechnical and Geoenvironmental Engineering. 149(1):04022117.

    Abstract

    The particle-scale shear and tensile strength measurements of Microbial Induced Calcite Precipitation (MICP) treatment have been investigated in this paper. Glass beads were used to represent sand particles. Three particle-scale test setups were developed to measure the tensile, shear, and cyclic shear strength of MICP treated CaCO3 bonds between glass beads. Sporosarcina pasteurrii bacteria were introduced to precipitate CaCO3 and form cementation bonds between glass beads. Preliminary particle-scale test (Test setup 1) was initially designed to measure the shear and tensile strength of CaCO3 bonds precipitated between glass beads mounted on optical fiber sensors with known properties. Shear and tension loads were applied to the CaCO3 bonds by the displacement actuators controlling the movement of movable stages. The deflection (measured in the tension test) and strain (measured in the shear test) of optical fibers were recorded to calculate the tensile or shear strength of the CaCO3 bonds. The improved particle-scale test setup (Test setup 2) was developed using a larger and stable reaction chamber, an automated injecting system, and stiff bending elements (instead of optical fibers) that were connected to glass beads to increase the success rate of measurement. The deflections of bending elements were measured to calculate the tensile and shear strength of the CaCO3 bond using the beam theory. The enhanced particle-scale test setup (Test setup 3) was developed to directly measure the shear and tensile forces generated in CaCO3 bonds using load cells and LVDTs to investigate the cyclic response of the CaCO3 bonds. For the tests using Test setup 3 with 100 and 200 μL bacteria injections, the shear and tensile strengths were ranged from 321 to 378 kPa and from 353 to 446 kPa, respectively.

  • Welcome to new members of our research group!

    We have four new members to our research group this year. They are Pan Ni (Post-doctoral researcher), Xinkai Wu (graduate student), Zhongyu Shi (graduate student), and Zizheng Luo (graduate student). Welcome to the group!

  • Effects of Enzyme and Microbially Induced Carbonate Precipitation on Pervious Concrete Piles

    Our paper titled “Effects of Enzyme and Microbially Induced Carbonate Precipitation Treatments on the Response of Axially Loaded Pervious Concrete Piles” has been accepted for publication in the Journal of Geotechnical and Geoenvironmental Engineering.

    Citation

    Lin, H., O’Donnell, S.T., Suleiman, M.T., Kavazanjian, Jr. E., and Brown, D.G.. 2021. “Effects of Enzyme and Microbially Induced Carbonate Precipitation Treatments on the Response of Axially Loaded Pervious Concrete Piles.” Journal of Geotechnical and Geoenvironmental Engineering. 147(8):04021057.

    Abstract

    EICP (enzyme-induced carbonate precipitation) and MICP (microbially-induced carbonate precipitation) treatments were applied through pervious concrete model piles to cement soil around the piles and enhance soil-pile interaction and pile capacity. The behaviors of the treated piles under axial compression loading were compared to each other and to an untreated pervious concrete pile. These tests were performed on 1/10th-scale piles in the Soil-Structure Interaction (SSI) testing facility at Lehigh University. The piles and surrounding soil were instrumented with strain gauges, bender elements, in-soil null pressure sensors, and a tactile pressure sheet. The responses of the pervious concrete piles and surrounding treated soil were compared through analysis of shear wave (S-wave) velocities in the treated and untreated soil zones, load transfer along the piles at the ultimate load condition, soil moisture content, calcium carbonate (CaCO3) content and ammonium (NH4+) concentration in soil, and the characteristics of the precipitated CaCO3 crystals along the soil-pile interface. In addition, comparisons of consolidated drained (CD) triaxial test results were made using sand without treatment and with EICP and MICP treatments. The results presented in this paper demonstrated that both EICP and MICP treatments can create a cemented soil zone surrounding the pervious concrete pile and improve the pile capacity and load transfer under compression loading.

  • Stiffness and Permeability of Sands Treated by Microbially Induced Carbonate Precipitation (MICP)

    Our paper on pore-scale distributions of CaCO3 during microbially-induced carbonate precipitation and their effects on sand permeability and stiffness has been accepted for publication in Soils and Foundations.

    Citation

    Lin, H., Suleiman, M.T. and Brown, D.G. 2020. “Investigation of Pore-Scale CaCO3 Distributions and Their Effects on Stiffness and Permeability of Sands Treated by Microbially Induced Carbonate Precipitation (MICP).” Soils and Foundations. 60(4):944-961.

    Abstract

    Physical properties of MICP-treated sands are controlled by CaCO3 distributions in pore space, which remain relatively unexplored. CaCO3 can deposit at the particles’ contact area (contact-cementing), coat sand particles (grain-coating), or create a cementation bridge between soil grains (matrix-supporting). The objectives of this paper are to determine the dominant CaCO3 distributions in pore space and investigate the effects of CaCO3 distributions on the small-strain stiffness (measured by S-and P-wave velocities) and permeability of MICP-treated sands. To achieve these objectives, cemented-sand and uncemented-sand models combined with three ideal CaCO3 distributions (contact-cementing, grain-coating, and matrix-supporting) were used to estimate the S-and P-wave velocities. In order to determine the dominant CaCO3 distributions in pore space, the calculated values from the models were then compared with experimental data. It was concluded that the dominant CaCO3 distributions were a combination of grain-coating and matrix-supporting. The effects of CaCO3 distributions at pore space on the variation of permeability were estimated using Kozeny-Carman and Panda-Lake models with three pore-scale cement distributions (pore-lining, pore-filling, and pore-bridging). The comparison between laboratory-measured and calculated permeability from the pore-filling Panda-Lake model for seven types of sands demonstrated a relatively good match with a maximum difference of one order of magnitude. The comparison suggests the pore-filling Panda-Lake model can be used for estimating the permeability of the MICP-treated sands.

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