Influence of production parameters on calcium sulfoaluminate cements

•40% limestone, 40% bauxite, and 20% gypsum yield a satisfactory CS¯A clinker.•Raw meal composition and kiln temperature greatly influence clinker phases.•Optimum gypsum amount for a CS¯A clinker is determined with isothermal calorimetry.•Addition of gypsum greatly reduces the heat evolved in the first few days.•Ye’elimite increases early strength and belite contributes to ultimate strength. The main appeal of calcium sulfoaluminate (CS¯A) cements is the possibility of reducing CO2 emissions. CS¯A clinkers can generally be produced at lower kiln temperatures and with lower limestone contents than required for portland cement clinker. However, it is important to assess the effects of various production parameters on the properties of CS¯A clinkers and cements. The influence of kiln maximum temperature, kiln retention time, and raw mixture proportioning on clinker properties, and those of water-to-cement ratio (W/C) and gypsum addition on cement hydration, were investigated. CS¯A clinkers were prepared in a laboratory furnace, with limestone, bauxite, and gypsum. Clinker and cement properties were explored with X-ray diffraction, isothermal calorimetry, thermogravimetric analysis, and scanning electron microscopy. Kiln temperatures as low as 1250 °C and retention times as low as 90 min. yielded satisfactory clinkers. Raw meal composition and calcination temperature have a greater effect on clinker phases than retention time. Hydration heat is affected mostly by raw meal composition. Hydration and strength gain were rapid until 3 d, after which they slowed down due to ettringite and AH3 coating the clinkers particles. Mortars with W/C = 0.6, achieved using citric acid as a retarder, gained ∼50 MPa strength at 28 d, 50–60% higher than mortars with W/C = 0.7.