Study on the performance of calcium sulfoaluminate cement–Portland cement blends with hydroxyethyl methyl cellulose

Calcium sulfoaluminate (CSA) cement and Portland cement (CSA–PC) can form blends with excellent performance. Adding cellulose ethers (CEs) can further adjust the macroscopic and microscopic properties of the blends. However, there are few studies on the effect of CEs on the performance of CSA-based blends. The results indicate that adding CE decreases the mechanical strength. CE delays the release of hydration heat of blends with high CSA cement content. Adding PC decreases the hydration heat of the blends. Meanwhile, adding 0.2–0.5% CE decreases the weight loss of ettringite and C–S–H gel in the blends with 85% and 70% CSA cement by about 1–2%, and decreases the content of chemically bound water by about 0.5–6%. The contents of the above hydration products and bound water decrease with the increase in PC content. In addition, as the CE content increases, the large capillary and macro pores significantly increase, resulting in an increase in cumulative pore volume and total porosity by about 0.08 ml/g and 10%, respectively. Furthermore, the cement mortars with high CE and CSA cement content have lower water capillary absorption. This study can provide theoretical guidance and a reference for the application of CSA-based repair materials in rapid repair and construction engineering.