Several studies are devoted to the calculation of serviceability life and design of foundation layers of road pavements, which are two of the main concerns of pavement engineering. For comprehension it is fundamental to have a knowledge of the mechanical behaviour of granular materials to reach a satisfactory pavement structural analysis and design. One of the most used parameters is the resilient modulus. The structural analysis starts with the assumption of constant elastic modulus used as an input for the calculation of the internal tensions in order to obtain resilient modulus using regression parameters k1, k2 and k3. By the use of constant Young modulus, the first problem was to verify if such approximation generates valid results.