Additions of γ-Al2O3 and Al(OH)3 powders produced at INETI from spent baths resulting from the aluminium transformation industry were made to a commercial cordierite batch formulation (without Al2O3 addition), known as DC4, developed by Rauschert Portuguesa Lda., in order to evaluate the possibility of replacing with benefits the conventional α-Al2O3 source used. The resulting samples were found to be denser than the commercial ones. This is related to the higher reactivity of these particular sources of alumina as compared to that added to the commercial product. Consequently, higher Young’s modulus (100-114 GPa) and flexural strength (80-98 MPa) were achieved for the developed materials in comparison to those obtained for commercial cordierite (96±2 GPa and 67±5 MPa, respectively). In addition, slightly lower thermal expansion coefficients were observed (3.6x10-6 K-1) and the thermal shock resistance was found to increase from 325 K to 350 K. The developed technology can be regarded as suitable for reducing the environmental impact of deposition of wastes from the aluminium transformation industry.