Influence of particle shape and size on the threshold fines content and the limit index void ratios of sands containing non-plastic fines

Although several empirical and analytical models are available to predict the threshold fines content (fthr) for sand-silt mixtures, none of them considers the combined effects of particle shape and size. In view of this, the current paper proposes a method to estimate the threshold fines content and the minimum void ratios for sand-silt mixtures at various contents of non-cohesive fines incorporating both parameters. The results of laboratory experiments along with existing data from literature, both for combinations of host and fine materials with various shapes and sizes were used in the analysis. The particle shape is represented through the particle regularity, ρ for both host and fine materials whereas the size is represented through the particle size ratio, χ. Empirical relations for the threshold fines content and the minimum void ratios at different fines contents were formulated, and proven to perform satisfactorily well over a wide range of particle shapes and sizes. In addition, the new empirical equations were validated by means of a comparison with existing results from literature.