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

In this paper, triaxial and cyclic direct shear behaviour of different sand mixtures were investigated by considering variations of shape, size and mixture content. In most studies, investigations on stress-strain properties of soils are 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 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 are 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 on the results.