Normalised behaviour of a non-plastic silt–pumice sand mixture

Abstract

The existence and failures of silty sand have been reported worldwide, and the behaviour of sand–silt mixtures at small to large strains has been intensively studied. Owing to the relatively low stress level achieved in laboratory testing, no unifying framework has yet been proposed for sand–silt mixtures. In the presented work, a crushable sand, made of pumice, was used as host sand so as to reach a unique normal compression line under pressures easily attainable in the laboratory. The sand was combined with non-plastic fines in proportions varying between 0 and 100%, and tested in compression and shearing with associated bender element testing for small-strain stiffness measurements. The unique relationship between pressure and volume on the normal compression line allowed for the normalisation of the data in a way that highlights the effects of fines irrespective of the density. It was found that once the effects of the fines on the index properties and compressibility have been cancelled, by normalising for volume, the behaviour of the sand–silt mixtures can be characterised as unique.