3-D micro-architecture and mechanical response of soil cemented via microbial-induced calcite precipitation

Abstract

We introduce the application of microbial-induced calcite precipitation via the ureolytic soil bacterium Sporosarcina Pasteurii in freeze-dried form, as a means of enhancing overall MICP efficiency and reproducibility for geotechnical engineering applications. We show that the execution of urea hydrolysis and CaCO3 precipitation persist as a “cell-free” mechanism upon the complete breakdown of rehydrated cell clusters. Further, strength and stiffness parameters of bio-cemented sands are determined. Medium-grained bio-cemented sand yields compressive strengths up to 12 MPa while, surprisingly, fine-grained sand yields up to 2.5 MPa for similar bond contents. To understand the observed discrepancies, we undertake a systematic study of the bio-cemented material’s microstructure, by combining a series of microstructural inspection tools. The study extends beyond conventional qualitative and textural characterization and provides with new insight into the material’s peculiar 3D micro-architecture. We apply a new methodology towards quantifying crucial microscopic characteristics such as the particle sizes of the crystalline bond lattice, the bond-grain contacts and particle orientations. Bonds are found to exhibit distinctive geometries and morphologies when MICP applies to different base materials. We thus contribute to the debate on the importance of factors affecting: (i) MICP efficiency, (ii) the mechanical response and (iii) peculiar micro-architecture of bio-improved geo-materials.

Microbe‐Mediated Extracellular and Intracellular Mineralization: Environmental, Industrial, and Biotechnological Applications

“…[ 288 ] When cracks are present, biocementation procedures are employed in which the “microbial mortar” is mixed with fillers such as sand or stone/marble grains for filling those cracks (Figure 12B) to encourage cementation of those filler particles produced by MICP (Figure 12C). [ 289 ] Calcium carbonate precipitation is induced by the fungus Colletotrichum acutatum in the presence of organic acid and low carbon conditions. This process prevents the degradation of CaCO 3 and may be used for preservation of deteriorated stone relics.…”

“…C) Reproduced under the terms of the CC‐BY Creative Commons Attribution 4.0 International license ( http://creativecommons.org/licenses/by/4.0/). [ 289 ] Copyright 2018, Springer Nature.…”

Assessing the Kinetics and Pore‐Scale Characteristics of Biological Calcium Carbonate Precipitation in Porous Media using a Microfluidic Chip Experiment

“…Empirical relationships have been established, relating the amount of calcium carbonate to engineering properties, i.e. porosity, permeability, strength, or stiffness (Al Qabany et al, 2011;Burbank et al, 2013;Mortensen et al, 2011;Terzis & Laloui, 2018;Van Paassen, 2009;Whiffin et al, 2007;Zhao et al, 2014). However, these empirical correlations exhibit large variability (Terzis & Laloui, 2018;van Paassen et al, 2010;Yasuhara et al, 2012).…”

Applications of Microbial Processes in Geotechnical Engineering

“…Treatment of sands via MICP has resulted in increases in unconfined compressive strength of greater than three orders of magnitude (e.g. and in some cases even over four orders of magnitude (Van Paassen et al, 2010 andLaloui, 2018). As a result of the increase in strength and stiffness afforded by MICP it has also been proposed for settlement reduction (Martinez & DeJong, 2009) and enhancing liquefaction resistance (Montoya et al, 2013).…”