Investigating Effects of Metakaolin Content on the Physical Properties of Concrete, and its Susceptibility to Colonization and Biodegradation by Sulphur Oxidizing Bacteria

Biogenic sulphuric acid attack on concrete is a concern worldwide, as it can lead to collapse of sewer infrastructure. Despite knowledge of the cause and the degradation pathways, not much is known about colonization patterns by sulphur oxidizing bacteria. These bacteria were grown on concrete in attempts to catalog degradation and colonization patterns. This was achieved using a battery of concrete property tests and experimenting with imaging techniques. Increased metakaolin content of concrete decreased sorptivity and chloride permeability of concrete while increasing strength and porosity. Concrete with higher metakaolin appeared more resistant to biogenic acid attack, despite increased porosity. Advances were made in protocols for imaging bacteria on a concrete surface, a challenge given the presence of autofluorescing materials in concrete. Information gained has shown that imaging bacteria on an autofluorescent surface can be achieved, and recommendations are made to further advance these efforts.