Corrosione di acciai zincati e al carbonio in calcestruzzi con cementi a base di solfoalluminato di calcio (CSA)

Sulfoaluminate-based cementitious binders have highlighted some advantages (in terms of compressive strength even at early curing, dimensional stability and a lower environmental impact of the production process) if compared to the ordinary Portland cement, which make them particularly interesting in relation to environmental sustainability. Based on several previous studies, it was found that concrete made with this type of cement has a pore solution less alkaline than that of ordinary Portland cement (OPC). The aim of this thesis is to evaluate the protection capacity that sulfoaluminate cements are able to offer to the embedded steel reinforcement bars. The experimental work is aimed to study, in different exposure conditions, the corrosion behavior of carbon and galvanized steel reinforcement bars, embedded in concrete with cement made by blending sulfoaluminate cement with traditional binders, characterized by two different water/cement ratios (0,47 and 0,55). Furthermore, it was evaluated the influence that carbonation, the presence of chlorides and the addition of calcium oxide (CaO) have on the corrosion behaviour of steel in mixtures with different type of cements. In addition to the electrochemical measurements to measure corrosion potential and corrosion rate of steel, studied mixtures were characterized with carbonation (natural and accelerated), absorption (capillary and by immersion) and electrical resistivity tests. The results have shown that concretes made by blending sulfoaluminate cement with traditional binders are able to passivate the steel bars embedded in them. In carbonated conditions, this type of concrete show a lower corrosion rate, if calcium oxide (CaO) is added into the mixture.