Investigation of interlayer shear failure of concrete bridge deck asphalt overlay utilizing shear strength envelopes

Abstract

The failure of interlayer between concrete bridge deck and asphalt overlay caused crescent-shaped cracks in the wearing course, resulting in intrusion of moisture into bridge structures and significant decrease in level of service for asphalt wearing course. It is of importance to establish design procedure to select and evaluate the interlayer materials for use in asphalt pavement on concrete bridges.This paper aimed to investigate the shear failure potentials on concrete bridge asphalt overlay using Finite Element (FE) model. The investigation was conducted on a project where a premature shear failure of asphalt pavement on a concrete bridge occurred. Both global and local FE models were established to obtain responses of interlayer under traffic loads. Sensitive analysis was conducted to identify the influence of overlay thickness and modulus on shear failure potentials. The spatial distributions of shear stress and normal stress at interface between concrete deck and asphalt overlay with and without horizontal shear forces were identified. The shear strength envelopes for interlayer were then utilized to evaluate the potential shear failure at interface.Results indicated the increase of overlay thickness may reduce the potential shear failure at interface. The presence of horizontal shear forces on pavement surface significantly increased shear failure at interface. The normal stress influenced the shear strength and needed to be considered in the lab shear test for design of interlayer system. A procedure which associated the load responses at interface with shear strength envelopes was presented. It may be used for evaluating potential interlayer shear failure as well as optimizing interlayer design.