Corrosion Resistance of Calcium Sulfoaluminate Cementitious Systems

This study investigated chloride binding and corrosion of carbon steel in calcium sulfoaluminate (CSA) cement concrete exposed to external chloride solutions. CSA pastes and concrete specimens were prepared using three water-to-cement ratios (w/c) (0.4, 0.5, and 0.6) followed by wet and air curing for 55 days. Ordinary portland cement (OPC) paste and concrete specimens also were prepared and analyzed for comparison. The primary hydration product of CSA was ettringite, and its quantity increased with the increase in w/c. Compared with OPC, the CSA pastes had a significantly lower chloride binding capacity and higher porosity, exhibiting poor performance in protecting the steel embedded in the concrete. In general, considering the compressive strength, chloride binding, and corrosion, air-cured CSA concrete performed worse than wet-cured CSA concrete.