|04-013||Dominika Madej||Madej, D.(AGH University of Science and Technology); Prorok, R.(AGH University of Science and Technology);||
This work investigates the time-dependent hydration behavior of 1:1, 1:2 and 2:1 molar ratio mixtures of reactive ?-Al2O3 and reactive MgO micro-powders in relation to the development of new hydraulic binder systems for in situ spinel refractory corundum castables. Mg-Al-CO3 hydrotalcite-like phases formed in the cementitious matrices cured in the corresponding curing condition up to 2 years of age at room temperature and at temperature of 50ºC were subjected to morphological, chemical and structural characterization using XRD, FT-IR, SEM and TEM techniques. The thermal decomposition of the hydration products of Mg-Al cementitious matrices has been studied by simultaneous DTA-TGA-EGA. The main difference between hydrated phases formed in the Mg-Al cementitious matrices obtained at different curing times is the thermal stability of interlayer water and hydroxyl groups within the structure of the layered double hydroxide (LDH) minerals. The effect of MgO/Al2O3 molar ratio on the hydration behaviour of reactive magnesia and hydratable micro-alumina hydrating mixtures was investigated and analyzed by microcalorimetry at 25ºC and 50ºC. The main conclusion from this experiment is that the MgO/Al2O3 molar ratio significantly affects the heat flow curves.
This study was founded by The National Centre for Research and Development within the framework of LIDER VIII project No. LIDER/5/0034/L-8/16/NCBR/2017.
Literature: D. Madej, Size-dependent hydration mechanism and kinetics for reactive MgO and Al2O3 powders with respect to the calcia-free hydraulic binder systems designed for refractory castables, J Mater Sci (2017) 52:7578-7590