A novel approach for magnesia hydration assessment in refractory castables

Magnesium oxide (MgO) or magnesia is one of the most important raw materials in the refractory industry. Because of its high refractoriness (melting point of 2800 °C) and corrosion resistance, the presence of this oxide in refractory compositions promotes an increase in the performance of pre-shaped linings for steel production [1], [2], [3] and [4]. Nevertheless, in refractory castables formulations, magnesia additions are restricted to coarse particles (usually above 50 μm) and contents of up to 10 wt.% due to their high tendency to react with water and the following great volumetric expansion promoted by this reaction [5], [6], [7], [8], [9], [10], [11], [12] and [13]. Despite the great number of studies describing the behavior of powdered magnesia or high-magnesia bricks, not much research has systematically been done related to its hydration behavior in castables [7], [13], [14], [15], [16], [17] and [18]. In this paper, aspects of magnesia hydration were briefly reviewed. Novel insights concerning magnesia hydration products generated under different curing conditions were attained adapting techniques already used in castables study.