Intergranular void ratio, e s , can be used as an alternative indicator to assess the mechanical properties of composite matrix of coarse and fine grains. In this paper, an intensive laboratory study of saturated coarse rotund sand and fine angular sand mixtures with various mix ratios is investigated by a series of oedometer and direct shear tests. Oedometer tests performed on the mixtures show that fines percentages and stress conditions affect the compression behaviours. Tests indicated that, up to a fraction of fines, which is named as transition fines content (FC t ), compression behaviour of the mixture is mainly governed by the sand grains. As the percentage of fines exceeds FC t finer grains govern the compression. Performed direct shear tests revealed that there is a relationship between the FC t and shear strength, which is harmonic with the oedometer test results.