Applications of High-Performance Concrete for Ultra -Thin Pavement Overlays (White-Topping)

Employment of High Performance Concrete (HPC) for thin overlays construction for aged flexible pavements has become a reality during the 90's, especially in the U.S.A. and some northwest European countries. While whitetopping old pavements was a technique employed from earlier decades of the twentieth century, the construction of ultra-thin concrete overlays (of 100 mm) for rehabilitation of pavements has been enhanced by the availability of technology for manufacturing HPC and the possibility of fast tracking. Ultra-thin whitetopping is a technique requiring several field conditions to be met concerning the old asphalt pavement in order to perform well as an overlay. They are full bond condition at the interface of HPC and asphalt concrete (generally provided by milling), asphalt concrete without fatigue cracking and rational joint spacing. All these factors, on the other hand, must be taken into account on the basis of the peculiar resistance of the HPC to be used. Within this context, this paper presents a study with regard to the HPC strength to be achieved for ultra-thin whitetopping purposes. It is supported by a numerical analysis based on a finite element solution for slabs-on-grade and takes into account the elastic properties for both HPC and old asphalt, as well as slab dimensions and the load critical position. An international review of HPC applied on whitetoppings around the world, that includes recent work in this field, is also presented.