LAUSR

This paper describes a new approach for synthesizing novel composite cements belonging to the system CaO–Al2O3–ZrO2 via the high-temperature reactions within the Ca7ZrAl6O18–Al2O3 system and characterizes products using X-ray diffraction (XRD), Rietveld XRD quantification, infrared spectroscopy, scanning electron microscopy combined with energy-dispersive spectrometry and heat flow calorimetry techniques. Quantitative comparison of the phase transformation in the samples 25 mass% Al2O3–75 mass% Ca7ZrAl6O18, 50 mass% Al2O3–50 mass% Ca7ZrAl6O18 and 75 mass% Al2O3–25 mass% Ca7ZrAl6O18 sintered in the temperature range 1300–1500 °C was presented. Detailed investigations of the reaction mechanism in the synthesis process in these samples show that calcium zirconium aluminate is unstable when it is heated with alumina, and it undergoes chemical reactions forming calcium aluminates with different CaO/Al2O3 molar ratios and Zr-bearing compounds (CaZrO3 or ZrO2). Probability of liquid-phase sintering of ceramics prepared from alumina and Ca7ZrAl6O18 that provides particle rearrangement increases with increasing the CaO/Al2O3 mass ratio of composites. Specifically, this paper discusses composition design and microstructural characterization for achieving modern calcia–alumina–zriconia composite cements. A model that explains the chemical and microstructural changes within the Ca7ZrAl6O18–Al2O3 system due to high temperature was proposed. This study extensively investigates the effects of the cement phase composition on the hydraulic activity in the Ca-aluminates and Zr-bearing compounds containing blended binder pastes.Graphical Abstract