Measurement of bulk mechanical properties of rootzone sand mixtures at two different moisture contents

This research aims at studying the effect of moisture on the bulk mechanical behavior (shear modulus, bulk modulus, compression profile and failure strengths) of rootzone mixtures (consisting of round-shaped sand particles) using a cubical triaxial tester. The round-shaped sand was tested at two different moisture levels (air-dried and -30 cm tension). From the triaxial tests, it was observed that the differences between the bulk modulus values for round sand in both moisture states were not significant. However, in both types of samples (dry and moist), an increase in bulk modulus was observed with isotropic pressure. Also, at any given isotropic. pressure in the hydrostatic triaxial compression (HTC) tests, the moist samples had a greater volumetric strain compared to dry samples. In the case of conventional triaxial compression (CTC) tests, the shear modulus values obtained for moist samples were significantly lower than the shear modulus values obtained for the dry samples. Moreover, no distinct failure was observed in case of moist samples, unlike dry samples that had a sharp failure stress value. It was therefore concluded that moisture does affect the compression properties of sand and leads to differences in initial bulk density, shear modulus, compression and failure profiles. Moreover, the presence of moisture makes the sand behave in a ductile-like fashion unlike its usual brittle-like characteristics in a dry state.