Synthesis and hydration behavior of calcium zirconium aluminate (Ca7ZrAl6O18) cement

Calcium zirconium aluminate (Ca7ZrAl6O18) cements were prepared by solid state reaction and polymeric precursor methods, and their phase evolution, morphology, and hydration behavior were investigated. In polymeric precursor method, a nearly single phase Ca7ZrAl6O18 was obtained at relatively lower temperature (1200 °C) whereas in solid state reaction, a small amount of CaZrO3 coexisted with Ca7ZrAl6O18 even at higher temperature (1400 °C). Unexpectedly, Ca7ZrAl6O18 synthesized by polymeric precursor process was the large-sized and rough-shaped powder. The planetary ball milling was employed to control the particle size and shape. The hydration behavior of Ca7ZrAl6O18 was similar to that of Ca3Al2O6 (C3A), but the hydration products were Ca3Al2O6·6H2O (C3AH6) and several intermediate products. Thus, Zr (or ZrO2) stabilized the intermediate hydration products of C3A.