Generally, the physical characteristics, namely the density, of refractory aggregates used in refractory castables are to be adapted to achieve high thermo-mechanical performances, thermal and chemical stabilities. An example is given with the comparison between tabular alumina (TA) and white fused alumina (WFA) for which a different strength performance after thermal treatment is generally observed. This difference could be attributed to the thermal mismatch between WFA aggregates and the matrix or/and a difference in their bonding linkage. Nevertheless, the generation of a microcrack network is also believed to adapt the thermal stresses during thermo-cycling operations and then positively contributes to the service life of the refractory lining. Thus, along with a specific chemistry, the microstructure of a refractory castable can be designed according to the physical and morphology characteristics of the aggregates for the improvement of its mechanical properties, in particular the thermal shock resistance.

The results presented in this paper discuss the evaluation of different types of refractory aggregates and their effect upon thermo-mechanical properties of their corresponding refractory castables, with a specific approach on thermal shock resistance assessment.