Microbial-Induced Calcium Carbonate Precipitation: from micro to macro scale
type: CreativeWork
description: Microbial-Induced Calcium Carbonate (CaCO3) Precipitation (MICP) is a biological process in which microbial activities alter the surrounding aqueous environment and induce CaCO3 precipitation. Because the formed CaCO3 crystals can bond soil particles and improve the mechanical properties of soils such as strength, MICP has been explored for potential engineering applications such as soil stabilisation. However, it has been difficult to control and predict the properties of CaCO3 precipitates, thus making it very challenging to achieve homogeneous MICP-treated soils with the desired mechanical properties. This PhD study investigates MICP at both micro and macro scales to improve the micro-scale understandings of MICP which can be applied at the macro-scale for improving the homogeneity and mechanical properties of MICP-treated sand. A microfluidic chip which models a sandy soil matrix was designed and fabricated to investigate the micro-scale fundamentals of MICP. The first important finding was that, during MICP processes, phase transformation of CaCO3 can occur, which results in smaller and less stable CaCO3 crystals dissolving at the expense of growth of larger and more stable CaCO3 crystals. In addition, it was found that bacteria can aggregate after being mixed with cementation solution, and both bacterial density and the concentration of cementation solution affect the size of aggregates, which may consequently affect the transport and distribution of bacteria in a soil matrix. Furthermore, bacterial density was found to have a profound effect on both the growth kinetics and characteristics of CaCO3. A higher bacterial density resulted in a quicker formation of a larger amount of smaller crystals, whereas a lower bacterial density resulted in a slower formation of fewer but larger crystals. Based on the findings from micro-scale experiments, upscaling experiments were conducted on sandy soils to investigate the effect of injection interval on the strength of MI…
abstract: Microbial-Induced Calcium Carbonate (CaCO3) Precipitation (MICP) is a biological process in which microbial activities alter the surrounding aqueous environment and induce CaCO3 precipitation. Because the formed CaCO3 crystals can bond soil particles and improve the mechanical properties of soils such as strength, MICP has been explored for potential engineering applications such as soil stabilisation. However, it has been difficult to control and predict the properties of CaCO3 precipitates, thus making it very challenging to achieve homogeneous MICP-treated soils with the desired mechanical properties. This PhD study investigates MICP at both micro and macro scales to improve the micro-scale understandings of MICP which can be applied at the macro-scale for improving the homogeneity and mechanical properties of MICP-treated sand. A microfluidic chip which models a sandy soil matrix was designed and fabricated to investigate the micro-scale fundamentals of MICP. The first important finding was that, during MICP processes, phase transformation of CaCO3 can occur, which results in smaller and less stable CaCO3 crystals dissolving at the expense of growth of larger and more stable CaCO3 crystals. In addition, it was found that bacteria can aggregate after being mixed with cementation solution, and both bacterial density and the concentration of cementation solution affect the size of aggregates, which may consequently affect the transport and distribution of bacteria in a soil matrix. Furthermore, bacterial density was found to have a profound effect on both the growth kinetics and characteristics of CaCO3. A higher bacterial density resulted in a quicker formation of a larger amount of smaller crystals, whereas a lower bacterial density resulted in a slower formation of fewer but larger crystals. Based on the findings from micro-scale experiments, upscaling experiments were conducted on sandy soils to investigate the effect of injection interval on the strength of MI…
author: Wang, Yuze
language: en
keywords: Microbial-Induced Calcium Carbonate Precipitation (MICP), soil stabilisation, micro-scale, macro-scale, particle-scale, crystal growth, bacteria, microscopy, ureolysis, Sporosarcina pasteurii, phase transformation, bacterial growth
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/def179af-98ab-404c-8a9b-dbe1d1b8c704/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2019-01-22
date modified: 2026-07-22T22:24:28Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.35552