Improvement of the negative-temperature properties of calcium sulphoaluminate cement by three multifunctional chemical admixtures

The construction of concrete in cold climates is associated with a significant energy consumption and an extensive carbon footprint. This is attributed to the production of raw materials and the necessity for additional measures to prevent frost damage. Finding suitable and environmental-friendly cementitious materials and admixtures for cold weather is a relatively straightforward and cost-effective solution. In this study, calcium sulphoaluminate cement (CSA) was selected, and low doses of three admixtures (lithium carbonate (Li2CO3), calcium mitrite (Ca(NO2)2), and calcium chloride (CaCl2)) were used at low dosages to modify the properties of CSA at sub-zero temperatures. The results showed that: The addition of Li2CO3 to CSA can significantly increase the early hydration of CSA, improve the early mechanical properties, shorten the curing time, and significantly reduce the content of frozen water in the pores. Ca(NO2)2 ensured the sustained late-stage development of CSA strength, which reached 90.5 MPa at −7+28 d; CaCl2 significantly lowered the freezing point of the cement paste and also improved the mid and late-stage strength.