Surface roughness: a key parameter in pavement interface design

The mechanical behaviour of the first interface under a surface layer is critical to pavement durability. Several of the distresses observed are mainly due to traffic loading or repetitive loading; they may also be related to the tack coat, which is often used to bond both layers, as well as to the application rate, curing time and cleanliness. The roughness effect however has not been heavily emphasised in pavement design. Out of such concerns, the interface model proposed in this paper makes use of a meso- and macroscale cohesive zone model, thus making it possible to take into account roughness and damage behaviour of the interface in either pure or mixed mode. The objective of this study is to propose an innovative method to identify these model parameters during in situ operations for practical engineering perspective. In this paper, an Interface Damage Model is analysed at the meso- scale with the actual roughness and idealised periodic roughness profiles. The parametric numerical analysis performed clearly shows the influence of roughness of these structures in shear mode. Moreover, a macro-scale interface damage model, which includes roughness as an internal variable, is proposed for pavement structures with smooth interfaces.