Investigation of Bonding between Asphalt Layers on Road Construction

Bonding of asphalt layers on road construction is usually examined with the pull-off test, measuring the adhesive power. This value however, is not appropriate to characterize the fracture-mechanical behavior of layer bondings and is thus inappropriate to be introduced into fracture-mechanical finite-element simulations. Therefore a simple procedure for measuring the fracture-mechanical behavior of layer bondings has been developed in this study. Cubic or cylindrical specimens (with their interface in their middle and a starter notch in the interface) are split under stable crack growth conditions. During testing, the complete load-displacement curve is determined until final fracturing of the bonding takes place. The load-displacement curve characterizes the mechanical behavior of the material bonding in the crack opening mode and is an important basis for a numerical treatment of interface problems. Results obtained with this new measuring procedure are presented and discussed. As an example, propagation of reflection cracks in a pavement consisting of two asphalt layers is simulated for single loading of the pavement.