Biodeterioration of ceramic materials by biogenic acids

Microorganisms contribute substantially to the degradation of ceramic materials such as natural stone, concrete, ceramics and glass. Active attack is caused by excreted mineral or organic acids. Passive biodeterior results from excreted hydrophilic slimes of heteropolysaccharides and/or protein (biofilm).

All microorganisms may be of importance in biodeterioration - chemolithotrophic and chemoorganotrophic bacteria, cyanobacteria, algae, fungi and lichens. Recently it has become possible to test the resistance of ceramic materials to microbial attack. Using a simulation apparatus it is possible to demonstrate the interactions between a microorganism and its ceramic substratum. Purely chemical and/or physical testing of materials is not sufficient to determine their resistance to a biologically induced attack. Biogenic sulphuric acid corrosion and nitric acid corrosion simulation experiments have demonstrated differences in the resistance of various concretes, which chemical testing failed to reproduce.

Thus, biotest systems allow selection from many different materials so as to find the most appropriate.