Permeability of compacted granule–clay mixtures

Abstract

Achieving a sufficiently low permeability for the aggregate-clay mixtures, whether used as the core of embankment dam or soil liner, is essential. The study illustrates the role of granule (bead or aggregate) content and size, confining stress and fabric anisotropy on the permeability of ceramic bead–lean clay and aggregate-fat clay mixtures. It is shown that depending on the plasticity of the clay, the permeability may decrease or increase with bead/aggregate content. The permeability also decreases when either granule size or confining stress increases. It is found that the permeability is affected by fabric anisotropy in such a manner that its value in the horizontal direction ( k h ) is more than that in the vertical direction ( k v ), however, k h / k v decreases towards 1 for bead contents equal to or below 40%. In high bead content mixtures (i.e., 60% beads) k h / k v reaches as high as 3 with an increase in the confining stress. The concept of the development of heterogeneous field of density in the clay is also used to demonstrate the impact of granule size and fabric anisotropy on the permeability.