Drying and autogenous shrinkage evolution of a blended CSA-portland cement concrete

In recent years, the building industry is becoming more and more aware about greenhouse gas emissions and the related environmental issues, having ordinary Portland cement (OPC) as its main CO2-emitting product. One of the possible eco-friendly alternatives is represented by calcium-sulfoaluminate cement (CSA): thanks to its lower energy consumption, different production process and raw materials, a reduction in the carbon footprint compared to OPC is achievable. However, the high raw material cost for pure CSA system production made them less likeable. According to the literature, a promising solution is the use of blended OPC/CSA systems, which limit the general cost and demonstrate good performance for several applications. Besides the high early-age strength, the most interesting property is related to the shrinkage reduction over time, when compared to an OPC-based system. In this paper, a comparison between a pure CSA and OPC system and a blend of the two binders at the ratio of 50/50 is proposed in terms of shrinkage. Considering the high strength class of such system, the rapid reaction at early age and the related possibility of demolding before the first 24 hours, both autogenous and drying conditions are considered in the evaluation of the shrinkage behavior.