Effect of Adding Sand on Clayey Soil Compressibility

Abstract

The effect of adding sand on clayey soil compressibility is investigated in this study. Four different percentage of clay-sand mixtures are used; 100% clay with 0% sand named 100C, 30% clay with 70% sand named 30C-70S, 15% clay with 85% sand named 15C-85S, and 100% sand named 100S. The used clay was obtained from Baghdad city in Iraq and classified as CH soil, while the used sand was taken from the sand quarry in Al-Khider area from Al-Muthana Governorate in Iraq and classified as SW soil. The initial dry unit weight for all mixtures is 18 kN/m3. The results show that the variations of the soil compressibility properties with soil components content changes almost linearly The results show that the preconsolidation stress (Pc) decreases with 19% and 38% and the rebound index (Cr) decreases with 4 and 53% and the compression index (Cc) decreases with 39 and 68% as the sand percentage increases with 70 and 85% respectively. Finally, predicted (fitting) Equations are achieved for the change of the soil compressibility properties with clay content with good agreement.