Microbially induced calcite precipitation in fine-grained soils through mechanical mixing

Document Type

Conference Proceeding

Publication Date

2025

Department

Department of Civil, Environmental, and Geospatial Engineering

Abstract

Microbially induced calcite precipitation (MICP), recognized as an eco-friendly method, has gained considerable attention in recent years. However, a primary obstacle to its widespread use is its application in fine-grained soils such as clays due to their very small pore sizes and low permeability. The small pore size and low permeability prevent the efficient delivery of bacteria, along with their required nutrients and also calcium sources, for calcium carbonate in the soil. This study aims to address these challenges by investigating a mechanical mixing method where the fine-grained soil is blended with bacteria and nutrients/calcium sources. The proposed method can be used in the Deep Soil Mixing method to reduce the use of cement grout. In this study, clayey samples were prepared, and solutions containing bacteria suspension and substrate solution were incorporated into the soil using the proposed mechanical mixing method. The precipitated carbonate content was measured using the Calcium Carbonate Content Chamber (ASTM D4373). Furthermore, Scanning Electron Microscopy (SEM) tests were conducted to examine the precipitated carbonates. Finally, soil strength changes were evaluated through Unconfined Compressive Strength (UCS) Tests. A comprehensive discussion of the results, the observed challenges during the lab experiments, and their implications for possible future field applications are presented.

Publication Title

2025 International Conference on Bio-mediated and Bio-inspired Geotechnics (ICBBG2025)

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