The particle size distribution is a very important tool for self-flow castables formulation since it determines its particle packing and is close related to the flowability. In this work, two different theoretical particle packing models are compared: Alfred and Andreasen. In the latter model the smallest particle diameter (D S) is not considered, unlike in the former. The self-flow castables rheological behaviour is evaluated as a function of the packing model used, keeping the distribution modulus (q) constant. The results are analysed based on the MPT parameter, which is already known for civil engineering area, but has not yet been investigated on refractory castables. Such parameter estimates the average distance between aggregates (particles larger than 100mm) in the castable. Compositions formulated according to Andreasen’s model reached flow values between 80% and 110%. In general, the flowability is reduced by increasing D Sand decreasing MPT, which results in an appropriate behaviour for vibra-casting castables. Finally, a new methodology for castables formulation is proposed based on the accumulated particle size distribution curve, MPT analysis and the evaluation of the matrix rheological behaviour.
castables; refractories; particle size distribution
