Thermal shock resistance of a refractory castable containing andalusite aggregate

One of the most important aspects to be evaluated when predicting the performance of refractory materials is their thermal shock resistance, especially considering the thermomechanical loads to which they are subjected. The methods currently used to predict thermal shock resistance behavior are based on Hasselman's studies, which take into account various experimental parameters. Thermal shock resistance can also be evaluated experimentally by applying thermal shock cycles and measuring the residual elastic modulus after each cycle. To predict and evaluate this resistance, test specimens of a commercial castable were cast, cured, dried and fired at 1000 degrees C and 1450 degrees C for five hours. Using Hasselman's parameters, the refractory fired at 1450 degrees C was predicted to present lower thermal shock resistance, which was confirmed by experimental thermal shock tests. The results indicated that the modulus of elasticity and modulus of rupture decreased by about 72% in specimens fired at 1000 degrees C, and by 82% in those fired at 1450 degrees C. Therefore, the specimens fired at 1450 degrees C showed lower thermal shock resistance. This finding underscores the importance of evaluating the behavior of castables with different microstructures resulting from different firing temperatures.