Ultrathin whitetopping - State-of-the-practice for thin concrete overlays of asphalt

Ultrathin whitetopping (UTW) is a concrete overlay of a distressed asphalt pavement, 50 to 100 mm thick, with close joint spacing. The overlay is specifically bonded to the existing asphalt pavement. It may or may not contain fibers. By bonding the UTW to the existing asphalt surface, the UTW forms a composite pavement section with the underlying asphalt, which reduces the stresses in the concrete layer. This composite pavement section delivers the longer life and durable performance characteristics of concrete pavement and is cost competitive with ordinary asphalt. Many areas are discussed, but not all questions about UTW are answered. A snapshot of the current state of the practice as it now stands is presented.