Blending eco-efficient calcium sulfoaluminate belite ferrite cement to enhance the physico–mechanical properties of Portland cement paste cured in refrigerated and natural winter conditions

The acceleration impacts of calcium sulfoaluminate belite ferrite (CSABF)—a cement produced from industrial side streams—on the hydration and strength development of Portland cement (PC) paste cured at −5 °C with and without pre-curing at room temperature were investigated. The impacts of eco-friendly CSABF cement content and pre-curing on the setting time and hardened properties of pastes were investigated. Freezing point of the paste and the amount of freezable water (FW) decreased with CSABF cement content and pre-curing. Hydration rate increased with CSABF cement content. By adding an optimal CSABF cement content, the compressive strength of paste cured at −5 °C increased by 500%. The effects of pre-curing on the compressive strength of the subzero-cured pastes were highly dependent on CSABF cement content and curing period. After 6 months, the outdoor-cured 70%PC/30%CSABF paste gained compressive strength comparable to that in the 90-day-old pair cured at −5 °C and continuous strength gain was detected up to one-year. The microstructural observations and porosity results are consistent with compressive strength measurements