Resilient Interface Shear Modulus for Characterizing Shear Properties of Pavement Base Materials

Abstract

This study used a large-scale cyclic shear test to investigate the interaction mechanisms between a geogrid and its surrounding aggregate in a cyclic loading mode to simulate traffic loads. Interactions at the geogrid–aggregate interface were quantified in terms of a parameter called resilient interface shear modulus Gi. The test protocol was derived from the triaxial test to apply cyclic shear loading under different normal stresses. Four interfaces were used in the study, including two types of base-course materials reinforced by a biaxial and triaxial geogrid. Results showed that the cyclic shear test had good repeatability, and the Gi of each interface was a function of both normal stress and cyclic shear stress: Gi decreased with an increasing cyclic shear stress but increased with an increasing normal stress. A modified three-parameter model was used to predict Gi, and the model parameters were determined for the three different interfaces. It was found that the three-parameter model could characterize the resilient interface shear modulus very well. The presented cyclic shear test along the resilient interface shear modulus shows enormous potential for characterizing geogrid-reinforced base materials.