Evaluation of Current State of Flexible Overlay Design for Rigid and Composite Pavements in the United States

Current composite pavement practices and key hot-mix asphalt (HMA) overlay design features, mainly to mitigate reflective cracking in the HMA overlay, used by state highway agencies in the United States are summarized. This information was obtained from a comprehensive survey conducted from January to May 2006 under a research effort for the New Jersey Department of Transportation to help minimize or retard the onset of reflective cracking in HMA overlays on portland cement concrete (PCC)/composite pavements. Information is provided on reflective cracking mitigation methods (successes and failures), current in-place composite/PCC pavement designs, treatments to prepare PCC pavement before HMA overlay and typical time until reflective cracking appears in the HMA overlay. Parameters that state agencies use to characterize pavement site conditions, including nondestructive testing, traffic conditions, and laboratory testing are also given. Further analysis is conducted by comparing the low temperature climatic conditions of the state to the low temperature performance grade of the asphalt binder commonly used in the HMA overlay. This examination and summary of survey findings on current pavement design practices and design features on the use of flexible overlays for rigid pavements in the United States will be of interest to state agencies, practitioners, and pavement researchers.