Morphology and fines type effect on packing of binary soils

Abstract

Three sands with different particle shapes were mixed with non-plastic fines and plastic fines (clay), respectively, in an entire fines content from 0 % to 100 %. Test results on determining the maximum and minimum void ratios show that both the particle shape of host material and the plasticity of fines can delay the onset of the threshold fines content. For a given fines type in binary soils, the threshold fines content decreases linearly with increasing overall regularity of host material, which proves the feasibility of overall shape parameter in describing soil properties. Meanwhile, the linear equation considering two parameters was derived from test data to evaluate the variation of the maximum and minimum void ratios with increasing fines content by volume for sand-fines mixtures, and the effects of shape of sand and plasticity of fines on the two parameters were investigated. Moreover, non-linear or higher degree equations considering two boundary conditions may have a better performance on describing the variation, but some limitations still exist.