Fracture-Based Friction Model for Pavement Interface Characterization

This paper presents a friction model that characterizes pavement layer interfaces. This model has been built on the basis of three major parameters, shear strength, interface reaction modulus, and friction, to define the behavior of tack coat interfaces. The most important property of this model is its ability to capture the entire range of interface responses, from the fully bonded (initial elastic) interface response to the response in the fully debonded state. A fracture-based elastoplastic constitutive relationship has been implemented for a frictional interface model. Debonding, which can occur in various modes (pure tensile, pure shear, shear with tension, and shear with compression), was formulated by use of a nonlinear softening model integrated into an elastoplastic constitutive model. The pressure dependency of the interface shear strength and dilation because of the surface irregularities are two of the frictional properties examined by the model. The paper includes several numerical examples to illustrate the model's extensive capabilities. The approach followed here involved derivations of the elastoplastic rate equations and integration algorithms and the development of interface elements. Next was the integration in ABAQUS software of algorithms and the interface elements as user elements. The parameters required for the model were obtained through a series of direct shear tests conducted with hot-mix asphalt (HMA)–concrete and HMA–HMA specimens bonded with different tack coat materials. The effects of temperature, normal pressure, and tack coat application rates were also characterized by use of the frictional constitutive model. The use of this model, with its inherent frictional nature, is desirable for interface problems, especially under various loading conditions (pure tensile, pure shear, shear with compression, and shear with tension).