Transient Properties of Refractory Castable with Hydraulic Binders

Refractory castables based on hydraulic binders have a widespread use in aluminium casthouses (furnaces, launders, etc.). Their selection is based on properties such as corrosion resistance to molten metal, mechanical behavior and insulation. Few studies concern the hydric exchanges between the refractory materials and the surrounding atmosphere, while this can affect their microstructure, durability or the quality of the produced metal, and may even have safety impacts. In this work, these exchanges have been studied in the case of refractory launders. A model has been built to describe the transient thermal behavior in the thickness of the launder material. The results have been compared to measurements obtained on an instrumented launder part. At the same time, an experimental approach has been developed to assess the transient hygrothermal behavior of refractory samples, through testing of moisture pick up in a climatic chamber at both ambient and at high temperature by thermogravimetric analysis. Observations have been correlated to hydration reactions at different temperatures.