Calcestruzzi con cemento a base di solfoalluminato di calcio - Protezione delle armature

Fast setting and hardening, high strength performance at early curing and, most of all, lower environmental impact, make sulfoaluminate-based cements attractive in relation to the sustainability of the construction industry. Nevertheless, the use of this type of binder in reinforced concrete structures requires a better knowledge about the protection provided to the embedded steel bars. Indeed, the pore solution of concrete made with sulfoaluminate cement has a lower alkalinity than that obtained using ordinary cement based on Portland cement clinker, so that the passivation of steel may be affected. This paper describes the results of an experimental study aimed at investigating the corrosion resistance of carbon steel bars in contact with concrete made by a sulfoaluminate cement. Laboratory tests showed that the pore solution of sulfoaluminate-based concrete is enough alkaline to induce passivation of embedded steel. Once the concrete is carbonated, negligible corrosion rates were measured on embedded steel even exposed up to 95% relative humidity at 20°C.