Mechanical and rheological behaviors of sands containing fines

Abstract

The present work was carried out with the aim of investigating the rheological behavior, in terms of contractance and dilatancy, and the mechanical behavior, in terms of shear resistance and mechanical characteristics, of sands containing different types of fines. This study is based on direct box shear tests that were carried out on three types of soils which were reconstructed by mixing clean sand with fines, namely silt, clay and clay loam. It is important to indicate that the mass percentages for sand replacement were 0, 10, 20, 30 and 40%. To do this, dry samples were prepared and subjected to shearing, under vertical stresses of the order of 100, 200 and 400 kPa. The results obtained showed that the maximum shear strength and friction angle of sand containing silt decreased while its cohesion increased, as the fines content increased. In addition, the maximum shear strength and friction angle of sand containing clay and silty clay decreased until reaching their minimum values ​​for contents equal to 20% clay and 30% clay and clay loam, respectively. The opposite phenomenon occurred for their cohesion which increased then decreased. It has also been observed that the more plastic the fines are, the higher their content in sand, the more this sand becomes contracting rather than dilatant.