Role of concrete-asphalt interface in bonded concrete overlays of asphalt pavements

Abstract

Bonded Concrete Overlay of an Asphalt pavement (BCOA) is a rehabilitation technique consisting of 50-175 mm thickness portland cement concrete overlay on an existing flexible, semi-rigid or composite pavement. This technique, that has also been known as thin (minimum 100 mm) or ultrathin whitetopping (thinner than 100 mm) in the past, relies on the composite action of the concrete and asphalt layers acting together with a third phase of the system being the interface between the two materials. For this study, the stiffness and strength/fatigue resistance of this interface have been characterized by means of a series of laboratory tests conducted on asphalt and composite cylindrical specimens under different loading and environmental conditions. Loading conditions were intended to reproduce the rapid traffic pulses and the slow temperature and shrinkage related actions, in both shear and vertical tensile modes. Environment related testing conditions included wet and dry, and temperatures between 4 and 40 °C, which is a range applicable to asphalt bases located under 100-175 mm thick bonded concrete overlays in California. Several conclusions were extracted that provide insight into the mechanical nature of the interface concrete-asphalt as well as the basis for designing a laboratory protocol for interface mechanical characterization.