Influence of Biogenic Acid on Concrete Materials

Abstract

Microbial sulphur cycle in sewers evocate the serious problem in the area concrete corrosion, health related aspects and odour. These problems are primarily related to the release of bacterially produced hydrogen sulphide from wastewater to the atmosphere during sewage transports that dissolves in the condensate on the sewer crown. In the event sulphur-oxidizing bacteria oxidize the dissolved hydrogen sulphide and other sulphur compounds to sulphuric acid, which corrodes the concrete. The concrete gradually expands causing cracks and ruptures, loss of strength and overall decay of concrete. The paper is focused on the investigation of the concrete specimens surface biodegradation study. From the viewpoint of concrete materials biodeterioration, mainly the bacteria sulphur- and sulphide-oxidising bacteria and sulphate-reducing bacteria are important and interesting. The role of bacteria mentioned above has been linked to the generation of the biogenic sulphuric acid resulting in corrosion process by dissolution of calcium containing minerals from the concrete matrices. The penetration of the corrosion was manifested by structural changes of concrete samples. The surface structure changes were by stereomicroscopy and atomic force microscopy (AFM) investigated.