| Unbound aggregates are extensively used in the unstabilized bases and subbases of flexible highway/airport pavements to provide load distribution through aggregate interlock that is essential to the integrity of the pavement. Tensile forces, however, cannot be transferred from particle to particle. Large horizontal tensile stresses are commonly predicted in the granular layers of flexible pavements when analyzed using isotropic material properties for unbound granular materials. In the last decade, it has been shown that incorporating the anisotropic behavior of granular materials in pavement analysis drastically reduces the tensile stresses computed within granular layers. It has been, however, extremely difficult to determine the cross-anisotropic material properties of unbound granular materials using the conventional triaxial setup.; A laboratory testing protocol and analytical solution technique have been developed based on theories of elasticity to determine the cross-anisotropic material properties of unbound granular materials from triaxial repeated load testing with using UI-FastCell which has custom designed for testing unbound granular materials with unique capabilities. The cross-anisotropic behaviors of different granular materials were studied with varying material type, gradation, moisture content, and stress levels affecting the resilient behavior. Finally, the new testing protocol and analytical solution technique have been developed to determine the cross-anisotropic material properties of unbound granular materials under stress path testing to simulate the moving wheel load. |
