Effect of clay content on the small and mid to large strain shear modulus of an unsaturated sand

The results of a series of laboratory test programme is represented to determine the small and mid to large strain shear modulus of an unsaturated sand mixed with a range of Kaolinite including zero to 30%. These were performed throughout a series of saturated and unsaturated cyclic triaxial loading and bender element tests. The results indicate that slight variation in the degree of saturation from 100 to 95% caused a drastic increment in maximum shear modulus. For the range of mid to large amplitudes of strains, the shear modulus reduction curves tend to decrease within the increment of fine contents. The normalised shear modulus reduction curve also appeared to initially be decreased within the increment of clay content up to 20% and consequently, it was slightly increased.