Durability of calcium sulfoaluminate cement concrete

Calcium sulfoaluminate cement (CSAC), first developed in China in the 1970s, has received significant attention because of its expansive (or shrinkage-compensating) and rapid-hardening characteristics, low energy-intensity, and low carbon emissions. The production and hydration of CSAC (containing ye’elimite, belite, calcium sulfate, and minors) have been extensively studied, but aspects of its durability are not well understood. Due to its composition and intrinsic characteristics, CSAC concrete is expected to have better performance than Portland cement (PC) concrete in several aspects, including shrinkage and cracking due to restrained shrinkage, freeze-thaw damage, alkali-silica reaction, and sulfate attack. However, there is a lack of consensus among researchers regarding transport properties, resistance to carbonation, and steel corrosion protectiveness of CSAC concrete, all of which are expected to be tied to the chemical composition of CSAC and attributes of the service environments. For example, CASC concrete has poorer resistance to carbonation and chloride penetration compared with its PC counterpart, yet some studies have suggested that it protects steel rebar well from corrosion when exposed to a marine tidal zone, because of a strong self-desiccation effect. This paper presents a succinct review of studies of the durability of CSAC concrete. We suggest that more such studies should be conducted to examine the long-term performance of the material in different service environments. Special emphasis should be given to carbonation and steel rebar corrosion, so as to reveal the underlying deterioration mechanisms and establish means to improve the performance of CSAC concrete against such degradation processes.