Microbially induced corrosion of cementitious materials: influence of cement composition, ambient humidity, and sulfur source (ZeUS)

• Applicants: Dr.-Ing. Gregor Gluth; Professor Dr. Matthias Noll
• Subject Area: Construction Material Sciences, Chemistry, Building Physics
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576117399

One of the most important tasks of the state is the maintenance of its critical infrastructure, including facilities and buildings for the retention, transport, distribution and treatment of wastewater. Such buildings are commonly made from concrete and heavily affected by microbially induced corrosion (MIC), a process in which sulfur-oxidizing bacteria (SOB) produce sulfuric acid, which in turn leads to the severe deterioration of the concrete. Accordingly, the requirement for repair measures and extensions of the sewage system is very high in Germany and other countries. However, the current knowledge about the MIC of concrete, particularly as regards the colonization of the concrete surfaces by SOB, and their activity and interactions, is incomplete. Therefore, the project comprises a systematic study of the influence of cement composition, humidity, and sulfur source on MIC. To this end, the evolution in time of the colonization of hardened cement pastes by microorganisms and their interactions under sewer conditions will be studied using microbiological analyses. The chemical composition of the surrounding aqueous solutions will be analyzed in parallel, and the deterioration of the cement pastes will be studied by microstructural analyses. Portland cement, blast furnace cement, calcium aluminate cement and two alkali-activated materials will be used as cements. This leads inter alia to different availabilities of aluminium and iron, two elements whose effect on MIC is particularly controversial. Through employment of a specifically designed test set-up, humidity conditions that approximate the conditions at the ceiling and in the tidal regions of sewer pipes, respectively, will be created. The employed nutrient solutions contain sodium sulfide, sodium thiosulfate, and potassium tetrathionate, respectively. Sodium sulfide approximates hydrogen sulfide, which is the sulfur source for the SOB in sewage systems, while thiosulfate and potassium tetrathionate are employed as nutrient in some current MIC test methods. Based on the experimental results, the significance of currently employed tests of the resistance of cementitious materials against MIC will be evaluated and proposals for the improvement of the test methods will be developed. Furthermore, the obtained insight into the influence of aluminium, iron, and other factors on the colonization by SOB constitutes a basis for the design of cementitious materials with very high resistance against MIC in sewage systems.

• DFG Programme: Research Grants