Self-healing geotechnical structures via microbial action

Botusharova, Stefani 2017. Self-healing geotechnical structures via microbial action. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Recent years have seen the growing interest in the novel field of biogeotechnologies. Of particular interest to researchers has been the microbially induced calcium carbonate precipitation (MICP) for geotechnical (stabilisation of soils) and geoenvironmental (immobilisation of contaminants) applications. The MICP process results in the formation of a brittle monolith from sand cemented by the microbial calcium carbonate which will, however, be subjected to chemical and physical deterioration over time. This will bring the need for repair of the earth structure which can be highly difficult and costly. This study investigates the possibility of incorporating a self-healing mechanism in the MICP that will allow the initially formed monolith to be healed after damage. MICP via a spore-forming, ureolytic organism, Sporosarcina ureae, was evaluated for its self-healing potential. The most commonly used organism in biocementation, namely Sporosarcina pasteurii, was found to not form spores. Experiments in aqueous solution showed that encapsulated (in calcium carbonate) sporulated bacteria can survive harsh conditions, starvation for periods of 6 months (while encapsulated within the mineral) and be able to germinate once exposed from the mineral matrix with availability of nutrients. The revived bacteria were then able to form the precipitation of further calcium carbonate. Additionally, the bacterium was able to go through cycles of self-healing multiple times without its activity being significantly affected. Also presented are experiments in particulate media which showed the ability of the organism to cause the cementation of sand columns. S. ureae was able to respond when a physical or chemical damage occurred to the monolith by germinating and producing again calcium carbonate which restored the functionality of the bio-cemented sand columns.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	Self-healing soils, microbially-induced carbonate precipitation, durability, sporosarcina ureae, spores, geotechnical structures
Date of First Compliant Deposit:	29 January 2018
Last Modified:	18 May 2021 13:45
URI:	https://orca.cardiff.ac.uk/id/eprint/108519

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