Acid Attack of Concrete Caused by Sulfur Bacteria Action.

Abstract

Abstract : The fact that concrete constituents are susceptible to attack and decomposition by acids is no new topic for discussion. The process by which certain genera of anaerobic bacteria produce acids has also been documented. However, most of the literature linking these phenomena with the deterioration of concrete structures has been addressed primarily to problems associated with concrete sewer pipes, and most of the reporting was done in the 1950's. This paper was extracted from a report of a recent investigation performed for the U. S. Army Engineer District, Huntington, into the combined effects of these phenomena on structural concrete. The investigation starts with the manifestation of the problem, i.e., the concrete in the outlet tunnels of two lakes being reduced to a 'mush' consistency to depths up to 1-1/4 in. (approximately 32 mm) over a period of about 5 years. The program of investigation includes a literature review, sample collection, and physical, chemical, and bacteriological tests. It is concluded that the deterioration is due to acid attack and is the final stage of a corrosive process caused by sulfur bacteria action. Immediate and long range remedial measures are suggested for consideration for implementation at both sites. Attention is drawn to the fact that undetected deterioration of other concrete structures may be in progress. (Author)