Effects of ordinary Portland cement on the early properties and hydration of calcium sulfoaluminate cement

Ordinary Portland cement (OPC) was used to enhance the early performances of calcium sulfoaluminate cement (CSA), and the hydration process of CSA-OPC composite was researched by XRD, TG, and SEM. Results showed that the rapid setting and high early strength of CSA can be achieved by the addition of 10-20 wt% OPC. The addition of OPC can evidently increase the ettringite content of CSA at early age, and change the morphology of ettringite significantly related to its high pH value. The difference of ettringite from CSA to CSA-OPC composite was mainly contributed to the presence of lime.