DIFFUSION OF HYDROGEN SULPHIDE IN CONCRETE

摘要

The most corrosive agent that leads to the rapid deterioration of concrete floors in barns with underground manure storage tanks is hydrogen sulphide, which is generated from anaerobic fermentation of manure. One of the objectives of the research on corrosion in livestock buildings at Guelph is to predict progress of corrosion numerically. Therefore, part of the study was to estimate constant and non-constant diffusion coefficients and chemical kinetics of H_2S for saturated mortar specimens. Six treatments were tested in the laboratory using a combustion furnace with infrared detection to determine the sulphur profiles at 90, 180, 270 and 360 days. The non-constant diffusion coefficient model exhibited better prediction of data than the constant diffusion model. Specimens made with 8% silica fume cement replacement had the lowest diffusion coefficients at infinite dilution, while similar Portland cement mortar specimens with 0.55 water-cement ratio had the highest. Results of H_2S consumption showed that it was the highest in the first week and then gradually diminished, which is an indication of a surface reaction followed by saturation.