Combining mixture design of experiments with phase diagrams in the evaluation of structural ceramics containing foundry by-products

This work compares the effects of the incorporation of foundry by-products (foundry sand dust and Waelz slag) on the technological properties of three different ceramic products fabricated with different clays and fired at different temperatures: wall bricks (850 °C), roof tiles (950 °C) and face bricks (1050 °C). To this aim, the mixture design of experiments (M-DoE) methodology was used to define the minimum number of mixtures necessary to model and predict the technological properties (water absorption, flexural strength, open porosity, linear firing shrinkage, weight loss and apparent density) in terms of raw materials contents: clay, foundry sand dust and Waelz slag. The results obtained were interpreted in terms of the chemical and mineralogical compositions of the final products, which showed the importance of combining the M-DoE methodology with the phase equilibrium predictions to better understand the development of the fired products final properties.