The objective of this work was to evaluate the influence of the particle size distribution of raw materials on the permeability, porosity and drying parameters of ultra-low cement high-alumina refractory castables. Both cumulative and discrete distributions were varied, following Andreasen's model for particle packing. Results have shown that the permeability is strongly affected by the fraction of aggregates in the composition due to the formation of pores at the matrix-aggregate interface. Porosity and permeability in the matrix were affected by the size of the matrix particles. Thermoanalysis has shown that the larger the aggregate content, the faster is elimination of water. Composition with q = 0.31 made of fine aggregates and coarse matrix yielded the castable with better performance during drying tests.
drying; particle size distribution; permeability; aggregates; refractory castables
