Low and ultra-low cement self-flow castables combine good high temperature performance and faster application rate. It has been shown that the castable self-flow ability and packing is a function of its particle size distribution and matrix rheological conditions. Bonadia and others proposed a castable formulation methodology based on these two concepts, focusing mainly the particle size distribution parameters. Stability maps, which predict the ideal matrix dispersion conditions, were generated by Studart et al. for aluminous castables in order to complete the proposed methodology. Such maps allowed the preparation of self-flow zero-cement (without any hydraulic binder) castables compatible with industrial applications. Since microsilica is essential for mullite formation in castables, the main objective of this work is to generate stability maps for alumina and microsilica-containing matrixes. The results showed a good correlation among the castable flowability and the optimum viscosity and yield stress regions indicated in the maps.
castables; refractories; rheology
