A growing demand for refractory castables with specific behavior has been inducing a continuous technological evolution, where one of the most important aspects is related to the hydraulic binders. The high alumina cements are the most important hydraulically setting agents used for bonding castables, mainly because they develop high strength within 6-24 h of placement. However, conventional castables show a characteristic drop in the mechanical strength in the 500 to 1000 °C temperature range, when the hydraulic bond is lost due to the dehydration process. In this work, the influence of dispersants in the refractory castables properties was evaluated as a function of firing temperature. It was verified that the hydrate type formed during the curing process depends on the dispersant used and defines the properties of castables. The additive that favored the dispersion of castable and decreased the water consumption resulted hydrates thermally more stable. This contributed to increase the mechanical strength at intermediate temperatures and it also influenced the thermomechanical behavior of castable at high temperature.
refractory castables; additives; thermal treatment
