ABSTRACT
Several researchers have studied anisotropy or directional dependency of material properties of aggregate systems (Tutumluer, et al. 1997), (Adu-Osei et al. 2001), (Kim et al. 2005). Tutumluer suggested the use of anisotropic constitutive models to characterize the response of aggregate base layers in flexible pavements (Tutumluer et al. 1997). He reported that the use of a cross-anisotropic model results in a drastic reduction or in some cases elimination of tensile stresses at the bottom of an unbound layer that are generally calculated using isotropic layered elastic solutions. He also found that compressive stresses throughout the aggregate layer and at the top of the subgrade are generally higher when the aggregate layer is considered as nonlinear and anisotropic. This conforms to results reported by Adu-Osei and Kim.
