Biodeterioration of reinforced sprayed concrete in subsea tunnels (peer-reviewed)

Paper in proceeding, 2018

Progressive microbial deterioration of steel fibre reinforced sprayed concrete for rock support has been observed in the Norwegian Oslofjord subsea tunnel due to reddish/brown and black biofilms. The concrete mix design corresponded to B45 and M45, with water/binder ratio = 0.42. Previous research on the microbial community has revealed complexity of the microbial composition involved in degradation of the cement paste matrix, material loss and steel fibre corrosion. In this study, we analysed microbial community dynamics and concrete degradation over time, biominerals and water chemistry composition to understand most important mechanisms involved in the biodeterioration process. Results showed temporal variations of microbial community and concrete degradation in association with changes in the water flow. The dataset from 2011 revealed a biofilm bacterial community dominated by Marinicella sp. (Proteobacteria) with a few ammonia oxidisers within Nitrosomonas and nitrite oxidisers within Nitrospinaceae. The data from 2015-2016 showed that the major phylum groups detected were Proteobacteria, Thaumarchaeota, Planctomycetes, Bacteroidetes, Actinobacteria, Acidobacteria, Nitrospirae, and Gemmatimonadetes with relative sequence abundance >2%.