Refractory materials are subjected to mechanical and chemical loads during application, which respectively lead to fracture and corrosion.  The understanding of the mechanical fracture and the microstructural modification after progressive thermal shocks is necessary for the suitable design of high performance refractory materials. The fracture process zone can be divided into two areas, where different toughening mechanisms are likely to take place: the crack tip and the following process region called wake region. In this study, the emphasis is laid on the microstructural mechanisms occurring in the wake region of the crack and the crack tip. Therefore, functional aggregates, namely fused eutectic aggregates of Al₂O₃-ZrO₂-SiO₂ and Al₂O₃-ZrO₂, and andalusite, are added to a model high alumina castable formulation based on tabular alumina. The discrepancy in thermal behavior between aggregates and matrix as well as phase transformation such like mullite formation favor further the nucleation of microcracks that reduce the stress field at the level of the crack tip. Two different grain fractions of tabular alumina (0.2-0.6 mm or 2.24-3.00 mm) are substituted by these functional aggregates. After sintering at 1 500 °C for 6 h, the samples are quenched up to 10 times at air without pressure from 950 °C to room temperature. The resulting elastic properties are examined after each thermal shock cycle and the residual bending strength after 0, 1, 3, 5, 7 and 10 thermal shocks. These results are correlated with Scanning Electron Microscopy analyses after the different thermal shock cycles.