Viscoelastic–Viscoplastic Model with Damage for Asphalt Concrete

A viscoelastic (VE)–viscoplastic (VP) model for characterizing asphalt concrete behavior is described. The parameters of the model are determined in the prepeak region of the loading, under small load. It includes two separate damage functions, one for each component of the deformation, to describe the material behavior under heavy load and in the postpeak region of the fracture. In order to extend the material characterization to the postpeak region, the size of the fracture process zone (FPZ) is evaluated from mapping the strain in a fracture test. The deformation in the FPZ, in the continuum framework is computed from total and local measurements. Uniaxial tests, including frequency sweep for the undamaged, linear VE component, repeated triaxial load for the undamaged VP component are conducted and used to derive the material properties in the prepeak region. A tension up to failure test is used to determine the damage functions.