Experimental Characterization of the Interface Damage Between Bituminous Layers: From the Interphase to the Interface Properties

The mechanical properties of surface courses inter-layers are a key parameter for the design of repaired or reinforced multi-layered asphalt pavement structures. The insufficiency of the interlayer bonding leads to significant decrease of pavement durability and recurrent distresses (slippage failures, top-down cracking). Hence, the main objective of this paper is to identify the input parameters for interlayer modeling, using DIC techniques. On the first hand, direct tensile test (DDT) and double notched shear test (DNST) are performed on two layered bituminous concrete specimens. The full field analysis allows to characterize an interphase thickness, the constitutive laws of both interphase and interface without thickness and the critical energy release rate in mode I and II. On the other hand, the contact surface morphology is analyzed by a fringe projection technique in order to determine the roughness parameters. A strong degree of similarity seems to be obtained between the interphase thickness and the roughness.