Whitetopping and Ultra-Thin Whitetopping – the US Experience

Concrete overlays of existing asphalt pavement, referred to as "whitetopping," is one of the most rapidly emerging technologies for rehabilitating pavements in the U.S. Although its use can be traced back to 1918, conventional (or classical), whitetopping became routinely used in the mid-1970's with use significantly increasing in the 1980's and 1990's. Additionally, "ultra-thin whitetopping" technology emerged in the early 1990's and its use is rapidly increasing. Ultra-thin whitetopping is intended primarily for use on low-volume roads, vehicular parking areas and general aviation airports. In 1996, new experiments were undertaken to evaluate "thin, composite whitetopping" on high-volume Interstate highways. In this paper, conventional whitetopping thickness design and jointing practices ate disLusscd. UILId-tIlill wliitctopping history, concepts, performancc studies, and methods for determining load carrying capacity are presented. New research to evaluate thin, composite whitetopping for high-volume roadways is summarized.