Abstract: Soil\|aggregate mixtures are composed of gravel, sand, and clay soils. Their permeability is highly inhomogeneous due to the complexities and variations of their macro and micro structures. In this paper, constant\|head permeability tests were performed by large diameter permeameters on soil\|aggregate mixture samples with five (5) different gradations. The factors that potentially affect the permeability of the soil\|aggregate mixtures are also discussed in this paper. These factors include: coarse as well as fine aggregate contents, coefficient of uniformity and mean grain size. Piping failure modes in the soil\|aggregate mixtures are also analyzed.