Fatigue Test and Mechanical Study of Adhesion Between Concrete and Asphalt

For the last ten years, new composite pavement structures have raised a significant interest. Based on the association of a concrete layer bonded to an asphalt sub-base, they lead to a reduction of the layers thickness and cost. A long-lasting bond is essential. This paper focuses on the mechanical study of the fatigue life of this bond. For these new techniques, as usual, the concrete layer is submitted to restrained shrinkage on great length. It leads to regular vertical cracking. As the two materials have different elastic properties, stress singularities appear at the interface, on the free edges generated by the cracks. This interface is considered as a third medium. It is assumed to have its own behavior and durability. A new laboratory test has been designed to study the initiation and the propagation of the crack at the interface. A first series of tests provides results on the durability of the bond. This paper also presents an in situ experiment aiming to evaluate the growth of a defect at the interface of a continuously reinforced concrete pavement bonded to an asphalt sub-base under traffic.