The behaviors of granular materials are controlled by not only the material stiffness but also strain level. Rigid sand and soft rubber particle mixtures are prepared with various volumetric sand volume fractions (sf). Small strain resonant column, intermediate strain oedometer, and large strain direct shear tests are performed to explore the behavior of the mixtures with different volumetric sand fractions. Threshold stain and minimum damping ratio increase with a decrease in the sand fraction. The linear responses of shear strain and damping ratio with the shear strain are observed at the mixture of sf=0.2. A linear shear wave velocity-void ratio trend is observed for each sand fraction. Shear wave velocity-void ratio and stress-axial strain relations are categorized into three groups according to sand fraction: rubber-like, sand-like, and transitional behavior groups. The friction angle increases with an increase in the sand fraction and no apparent peak strength is observed in the mixture except for sf=1.0. This experimental study suggests that the strain level is one of the important factors to determine the behavior of the mixtures.