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Properties and Behavior of Sandy Soils by a New Interpretation of MICP

  • 0Japanese Geotechnical Association for Housing Disaster Prevention, 1622, Oshikiri, Shimizu-ku, Shizuoka 424-0008, Japan.
Materials (basel, Switzerland) +

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February 26, 2025

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February 26, 2025

View abstract on PubMed

Summary

This summary is machine-generated.

Microbial Induced Carbonate Precipitation (MICP) research faces challenges in quantifying microbial viability. This study establishes a new method using carbonate formation rate (CPR) to reliably estimate bacterial viability for improved MICP applications.

Area Of Science

  • Geotechnical Engineering
  • Microbiology
  • Biogeochemistry

Background

  • Microbial Induced Carbonate Precipitation (MICP) is an innovative ground improvement technology with expanding applications in soil stabilization and remediation.
  • A significant challenge in MICP research is the accurate and quantitative evaluation of microbial viability, hindering consistent research outcomes and technology adoption.
  • Bacterial properties can fluctuate over time and with environmental changes, complicating their use in engineering applications.

Purpose Of The Study

  • To develop a reliable method for quantifying microbial viability in MICP applications, overcoming the limitations of traditional urease activity measurements.
  • To establish a standard relationship between microbial mass (Optical Density - OD) and carbonate formation rate (CPR) for viable bacteria.
  • To enable a unified evaluation of MICP technology, even with aged bacteria or when direct viability testing is not feasible.

Main Methods

  • Defined the carbonate formation rate (CPR) as a function of microbial mass (OD) for viable bacteria, replacing urease activity measurements.
  • Experimentally established a standard OD-CPR relationship.
  • Introduced OD* to represent the required amount of microorganisms and defined the relationship OD = Rcv OD*, where Rcv is the viable bacterial rate, to convert between OD* and OD.

Main Results

  • A method for estimating microbial viability was established based on the OD-CPR relationship.
  • The Ca<sup>2+</sup>/OD ratio was identified as a critical factor controlling inhibition in MICP.
  • Demonstrated that CPR is proportional to viable OD, Rcv, and OD* at a specific Ca<sup>2+</sup>/OD ratio (8.46 M), enabling unified evaluation using OD* with aged bacteria.

Conclusions

  • The developed OD-CPR relationship and the use of OD* provide a standardized approach to evaluate MICP efficacy, irrespective of bacterial age or precise viability.
  • This method overcomes the variability of bacterial properties, facilitating more consistent and comparable research results in MICP.
  • The findings support the broader application and acceptance of MICP technology in geotechnical engineering and environmental remediation.

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