Modifications in hydration kinetics and characteristics of calcium aluminate cement upon blending with calcium sulfoaluminate cement

The present study explores the modifications in hydration kinetics and characteristics of calcium aluminate cement (CAC) upon blending with calcium sulfoaluminate (CSA) cement. CAC was replaced with CSA cement at 0, 30, 50, 70, or 100 wt%. The hydration properties of the samples were evaluated and characterized by X-ray diffraction, thermogravimetric analysis, 27Al nuclear magnetic resonance spectroscopy, compressive strength tests, isothermal calorimetry, autogenous shrinkage measurements, and thermodynamic modeling. The test results indicated that the incorporation of CSA cement altered the hydration pathway of the CAC clinkers, promoting the formation of AFm phases over katoite. In addition, the addition of CSA cement increased the compressive strength development and reduced the total hydration heat release. In contrast, the occurrence of heat release rate peak was advanced by the addition of CSA cement. Furthermore, the CSA cement compensated for the autogenous shrinkage development of the samples, reaching almost no volumetric movement in the sample with 50% CSA cement.