An extensive experimental and analytical investigation is beingcurrently carried out on the mechanisms leading to the initiationand propagation of fatigue damage in the top layers of asphaltconcrete pavements when subjected to various types of loading.One of the major goals of the investigation is the developmentand finite element implementation of a triaxial, strain rate sensitive,history and temperature dependent constitutive model for asphaltconcrete under arbitrary states of stress.

Because of the hierarchical formulation of the model, the analystcan activate, at will, those features of the model which he considersrelevant to his specific interests. Explicit procedures are suggestedfor the experimental determination of the parameters. As a minimum,only uniaxial test results are needed for determination of thebasic parameters. An actual example of such a procedure is presented.

In its current, prototype formulation, the model has been implementedin the finite element code CAPA3D. Results of the utilizationof CAPA-3D for the investigation of the dynamic non-linear responseof asphalt concrete pavements are reviewed in the last part ofthis contribution.