Biodeterioration of Concrete and Stone

摘要

Concrete and carbonate stone have been used extensively in the construction of both modern and historic buildings, statues, and tombstones. These materials support a diverse community of microorganisms. Organic acids produced as byproducts of microbial metabolism can cause deterioration of both concrete and stone. In this study, biofilm bacteria were cultured from limestone surfaces, and the effects of organic acids were determined by measuring changes in stone mass as well as with a new technique, micro computed x-ray tomography (μCT). Bacteria adapted to growth at high concentrations of organic carbon or at high salt concentrations were the most abundant microorganisms found in biofilms, while bacteria adapted to high pH or low levels of organic carbon were found in smaller numbers. Some organic acids produced as by-products of microbial metabolism were corrosive. Oxalic acid was passivating and protected stone from the corrosive action of other acids. Analysis using μCT demonstrated the protective action of oxalic acid.