Corrosion of Steel Reinforcement in Mortar exposed to Hydrogen Sulphide, Part 2: Diffusion Tests

Reinforced concrete in livestock buildings is subject to severe corrosion if manure is stored below slatted floors. The major corrosive agent is hydrogen sulphide. Laboratory diffusion tests were conducted on mortar specimens to allow the prediction of sulphur concentrations in concrete components in a barn. Diffusion coefficients for H2S were determined at 90, 180, 270 and 360 days for six treatments and used in 12 finite element analyses. The results for specimens made with 8% silica fume cement replacement (SFC) performed best and confirmed the results of the impressed voltage and of the electrochemical potential tests reported in Part 1. Similarly, the results for specimens made with Portland cement using a water-cement ratio of 0· 55 (PC55) performed poorest, again confirming the results of the impressed voltage and of the electrochemical potential tests reported in Part 1. The remaining specimens performed better than PC55 and worse than SFC. The diffusion coefficients were used in finite element diffusion analyses of a single slat. The results indicate that the use of silica fume cement for the concrete approximately doubled the life of a floor slat when compared with Portland cement with a watercement ratio of 0·45.