Influence of grain shape and gradation on the shear behavior of sand mixtures

This paper investigates triaxial and cyclic direct shear behaviour of different sand mixtures, considering variations of shape, size, and mixture content. in most studies, investigations of stress-strain properties of soils were carried out using clean sands. however, granular soils in the field may contain a considerable amount of grains in different physical characteristics (i.e., shape, size). therefore, behaviour of the various sand mixtures in triaxial compression and cyclic direct shear testing apparatuses has received our attention in this study. two different sizes (0.25 mm-0.5 mm and 1.0 mm-2.0 mm) of sands with distinct shapes (rounded and angular) were tested in triaxial and cyclic direct shear apparatuses. the mixtures of coarser and finer geomaterials were tested in various mix ratio values from 5% to 50% by weight. based on the examinations during shearing of these materials, it was observed that behavior of the sand mixtures was closely related to the grain shape of host materials as well as fines content in both testing apparatuses, whilst size of the sands was not found to be significantly effective in the results.