Impact of cement composition on the adsorption of hydrogen sulphide and its subsequent oxidation onto cementitious material surfaces

Mortars based on different compositions (cast with calcium aluminate cement (CAC), ordinary Portland cement (CEM I), blended Portland cement (CEM III, CEM IV, CEM V) and super sulphated cement (SSC)) were exposed to gaseous H2S. The most soluble phases from cement lead to the presence of ions in a water layer formed on the mortar surface and these ions provoke acceleration or slowdown of H2S adsorption. After that, H2S oxidizes into elemental sulphur and then into gypsum crystals. The cement types only affect the kinetics of these oxidation reactions.