Study on the evolution patterns of concrete lining’s physical and mechanical properties under sulfuric acid corrosion conditions

Abstract

During operation, deep water storage and drainage tunnels may face sulfuric acid corrosion resulting from microbiologically induced chemical reactions. In this study, sulfuric acid corrosion experiments were performed on C60 concrete specimens with steel fiber volume ratios of 0% (plain) and 1% using a sulfuric acid solution with an initial pH of 1. For one-face corrosion, five faces of cubic concrete samples were coated with exposed resin, leaving only one face exposed to sulfuric acid. For all-face corrosion, all faces were exposed to sulfuric acid. Concrete corrosion under different loading conditions was compared by adding weights on top of the concrete. Rate of mass change variations and uniaxial compressive strength at various corrosion time points were monitored. The results indicated that after sulfuric acid corrosion, there was an increase in the mass but an overall decrease in the strength of the specimens. Compared with all-face corrosion, one-face corrosion led to a smaller increase in the mass of the concrete specimens and a more substantial decrease in strength, primarily because of the slower corrosion rate and reduced gypsum formation. Compared to plain concrete, steel fiber-reinforced concrete experienced a lower increase in the mass of the concrete specimens because the steel fibers obstructed sulfuric acid infiltration. However, there was significant corrosion of the steel fibers and surrounding concrete owing to accumulation of sulfuric acid around the former, resulting in a more substantial decrease in the uniaxial compressive strength of the steel fiber-reinforced concrete. With increasing load, the rate of change in the concrete mass initially decreased and then increased; this could be because increased loads densify the concrete, hindering sulfuric acid infiltration and promoting the development of microcracks within the concrete, thereby enhancing the effects of sulfuric acid corrosion.