Magnesium oxide (MgO) or magnesia is one of the most important raw materials for the refractories industry. Because of high refractoriness (melting point of 2800 ºC), corrosion resistance in basic environments and relatively low costs, its use in bricks has allowed a significant increase in the performance and service life of these materials. However, its use in refractory castables did not attain the same impact in industrial applications because of its great tendency in react with water and the consequent volumetric expansion generated. Therefore, magnesia additions in castables has been kept in small amounts (bellow 10 wt%) and restricted to large particles (> 100 µm). In the present work, several reports on magnesia hydration in refractory castables, its effects on the castables processing and the anti-hydration techniques were critically reviewed.
refractory castables; magnesium oxide; magnesia; hydration
