Van Der Bergh, JM (2023) Bio-inspired Bacteria-based Concrete for Durability Increase of Structures. Doctoral thesis, Liverpool John Moores University.

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Abstract

This doctoral dissertation explores an alternative approach to the crack repair in concrete structures, specifically focusing on the application of bacteria-based self-healing techniques. Concrete, a prevalent construction material, exhibits robust compressive strength but is susceptible to tension-induced cracking, jeopardising structural longevity. Traditional repair methods for such cracks are often expensive and time-consuming. In contrast, this study delves into the feasibility of an innovative method wherein bioagents, comprising bacteria and a calcium nutrient source, are introduced post-construction to address existing cracks.

The research methodology involved comprehensive experiments on samples of varying scales, encompassing macro and micro dimensions. Different bioagents, developed and synthesised for this purpose, were applied using diverse techniques under varying incubation conditions to simulate real-world scenarios. The central objective of the investigation was to elucidate the potential of this external repair approach, identifying knowledge gaps and avenues for enhancing crack repair techniques.

The outcomes of the study revealed a distinct process of precipitate formation within treated cracks. This mechanism involved the initial development of needle-like and cubic crystals on the crack walls, presumed to be hydration products of the substrate material. Subsequently, bacterial metabolic by-products contributed to filling the crack voids, binding the needle-like crystals on both sides. The effectiveness of the bioash on precipitate formation rate varied across bacterial strains. An optimisation study highlighted the yeast extract broth-based repair agent, applied through the "dropping" technique, as the most efficacious in reducing transitional and gel pores - known contributors to concrete shrinkage.

The materials developed in this research, derived from biobased sources, are anticipated to play a pivotal role in evolving strategies for crack repair in concrete structures. However, their integration into conventional construction practices necessitates standardisation through rigorous characterisation. Future research endeavours should focus on a deeper understanding of the viability of bacteria used for MICP, correlating specific biobased agents, application techniques, and incubation conditions with resultant mineral formations. This will contribute to advancing the practical application of these alternative materials in the construction industry.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	MICP; self-healing; concrete; external repair; durability; crack repair; sporosarcina pasteurii; sutcliffiella cohnii; bioash
Subjects:	T Technology > TH Building construction
Divisions:	Civil Engineering & Built Environment
SWORD Depositor:	A Symplectic
Date Deposited:	05 Dec 2023 16:51
Last Modified:	05 Dec 2023 16:52
DOI or ID number:	10.24377/LJMU.t.00022012
Supervisors:	Brás, AA, Riley, M and Miljević, B
URI:	https://researchonline.ljmu.ac.uk/id/eprint/22012

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