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The bulk mechanical behavior of root-zone sand mixtures i.e. shear modulus, bulk modulus, compression profile and failure strengths were measured using a cubical triaxial tester. Four different sand shapes, i.e., round, sub-round, sub-angular and angular, were tested at two different moisture levels, air-dried and 30 cm. For all sands, an increase in bulk modulus was observed with increasing isotropic pressure. The dry round sand without peat had the highest bulk modulus value of 27.5 MPa at 352 kPa mean pressure; whereas, the dry sub-angular sand without peat had the highest failure strength value of 193 kPa at 38 kPa confining pressure. In general, moisture increased compressibility of sands and decreased failure strength and shear modulus values. Peat had a dominant influence on the mechanical response i.e., the hydrostatic compression for all four sand shapes with peat had similar compression profiles. When peat and moisture were added to the sands, the mixture became most compressible and easiest to fail among all treatments. In addition, the changes of mechanical properties were noticeable.