MODELLING OF PAVEMENT MATERIALS –NUMERICAL AND EXPERIMENTAL ASPECTS- Sandra M.J.G. Erkens 1 Xueyan Liu 2 Tom Scarpas 2 André A.A. Molenaar 3 Johan Blaauwendraad 2 ABSTRACT: Results of an extensive experimental and numerical research project on the response of Asphalt Concrete (AC) are presented. In the projects a material model for AC is being developed and implemented in the Finite Elements package CAPA-3D. Also, the test set-ups, instrumentation and test procedures necessary to characterise the material and determine the model parameters were developed. In an early stage of the project it was recognised that failure in tension and compression followed a different mechanism and needed to be described separately in order to capture the response to alternating loads. From the results of uniaxial tension tests it became apparent that also in tension a pronounced non-linearity occurred prior to the peak load. The adaptations necessary to incorporate this in the model are presented in this paper. The response predicted by the model relations is compared to that observed in laboratory tests to validate the model relations and it can be seen that the observed behaviour is described quite well by the model. INTRODUCTION Most current day design and analysis tools in road engineering are based on the Multi Layer approach or similar techniques. Although applicable to a large class of pavement problems, the limitations of these tools are now widely recognised. The most important one is the required homogeneity of the characteristics per layer, which means that discontinuities or the variations in material response caused by the stress distribution in horizontal direction cannot be taken into account. To extend the analysis possibilities, alternative tools are emerging among which is the Finite Element Method. This method allows the analysis of various geometries. Since the structural and material characteristics are entered separately, once a reliable material model is available it can be used to analyse any geometry. Output can also be obtained at any point in the geometry, which allows the investigation of damage mechanisms. The resulting insight in what 1 Road & Railway Research Laboratory, Dept. of Civil Engineering, Delft University of Technology, the Netherlands, s.erkens@citg.tudelft.nl 2 Structural Mechanics group, Dept. of Civil Engineering, Delft University of Technology, the Netherlands 3 Road & Railway Research Laboratory, Dept. of Civil Engineering, Delft University of Technology, the Netherlands