Prediction of fatigue failure at asphalt concrete layer interface from monotonic testing

This study investigated the characterization of interface shear behavior in asphalt concrete through the estimation of the stress ratio (SR). This parameter, originally identified as the ratio between predicted interface stress from a finite element model (FEM) and interface shear strength at the corresponding normal stress, was assumed to be dynamic. As part of the experimental plan, monotonic tests on double-layered asphalt specimens were performed. Dynamic evaluations of the number of repetitions to failure under several stress conditions, equal to or higher than stresses computed from an FEM of the pavement structure, were also performed. The failure curves of the two testing modalities show similar patterns on the Mohr plane. The Hoek-Brown shear strength failure criterion and the three-dimensional surface that best fits the dynamic outcomes were considered. In this scenario, the SR referred to the proportion between the applied shear stress conditions in the dynamic modality and the maximum stress from monotonic tests. For the same predicted failure repetitions, SR assumed a constant value. Correlating monotonic and dynamic results could be an important approach both in furthering knowledge of interface shear strength and in predicting information about failure under repetitive loading applications based on simple monotonic tests.