Abstract
Composite cements belonging to the CaO–Al2O3–ZrO2 (C-A-Z) and CaO–SrO–Al2O3–ZrO2 (C–Sr-A-Z) systems were evaluated as alternatives to calcium aluminate cements (CACs) for use in the refractory castables technology. The mineralogical phases in the as-synthesized C-A-Z and C–Sr-A-Z clinkers confirmed by XRD and SEM-EDS were CaAl2O4, Ca7ZrAl6O18 and CaZrO3 or (Ca,Sr)Al2O4, (Ca,Sr)Al4O7 and (Ca,Sr)ZrO3, respectively. The present work aimed at developing novel Zr-containing cements with excellent mechanical performance, i.e. modulus of rupture and cold crushing strength. Both hydration behavior of the C-A-Z, C–Sr-A-Z, CAC and their hydration products, were studied with isothermal calorimetry, XRD, SEM-EDS and NMR. Impedance camera instrument was firstly successfully applied for time-resolved electrochemical impedance spectroscopy measurements under nonstationary conditions and record the time-dependent evolution of the Nyquist plots for hydrating cement pastes. A sharp increase in the real part of impedance Z’ versus hydration time were corresponded to the second exothermic peak detected on the calorimetry curves.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have