Stress-strain behavior of a compacted sand-clay mixture

Compacted soils with high fines content are regarded as disqualified backfill materials for retaining earth structure. For economical reasons, their beneficial use warrants to be studied. In this paper, a sand-clay mixture containing 40% fines was prepared and compacted with water content at optimum, and a series of 'unconventional' drained compression tests were conducted. The specimens were unsaturated specimens and the confining pressure used for the tests was from 30 kPa to 150 kPa. The volume change of unsaturated specimens was measured from radial displacements using gap sensors. The sand-clay mixtures showed a highly overconsolidated behavior and the Mohr-Coulomb failure envelope was nonlinear. The results also showed that the angle of internal friction decreased with an increase in the confining pressure, whereas the elastic modulus increased with an increase in the confining pressure.