Durability of blended cements containing sulfoaluminate clinker

The cement industry is strongly committed to a very ambitious 'zero emissions' trajectory while maintaining the highest level of quality and durability performance. The zero emissions target will be reached using several leverages, including the reduction of the clinker content in cement. Low-clinker cements represent a market solution and are already efficiently implemented in many European countries. However, the early-age strength development of low-clinker cement at less than that of ordinary Portland cements (OPC) with a higher clinker content. The use of blends of low-clinker Portland cement and calcium sulfoaluminate (CSA) cement could meet the need for a low carbon dioxide binder with high early strength. In this work, the behaviour of four blended cements containing CSA clinker, OPC clinker, limestone, fly ash, pozzolan and slag was characterised using different techniques in terms of resistance to carbonation, chloride migration and sulfate attack. The findings indicate that durability performance is enhanced when supplementary cementitious materials (SCMs) with pozzolanic or latent hydraulic activity are present, as opposed to the presence of limestone. SCMs also play an active role in the OPC-CSA matrix. A blend of CSA-OPC cement and slag represents a system characterised by both high early and late strengths, along with favourable durability behaviour.