Performance assessment of Wisconsin's whitetopping and ultra-thin whitetopping projects
Wisconsin Highway Research Program
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Whitetopping (WT) overlay is a concrete overlay on the prepared existing hot mix asphalt (HMA) pavement to improve both the structural and functional capability. It?s a relatively new rehabilitation technology for deteriorated HMA. If the slab thickness is less or equal to 4 in., it is referred to as ultra-thin whitetopping (UTW). The primary objectives of this study are to catalog the WT and UTW projects in Wisconsin, document pertinent design and construction elements, assess performance and estimate a service life of these projects. A comprehensive literature review was performed. A database of the WT and UTW projects was established covering 18 projects built from 1995 to 2007 in Wisconsin. The performance of these WT and UTW projects was assessed, by means of shear strength tests on field cores, falling weight deflectometer (FWD) tests on selected projects, and field distress survey on in-service projects. FWD backcalculation methods for WT and UTW pavements were studied and a Critical Distance Method was proposed and utilized for UTW pavement. Fatigue life was analyzed using 18kip, 22kip and 26kip single axle load level. Performance assessment was conducted using both Pavement Condition Index (PCI) and Pavement Distress Index (PDI). The performance of WT projects in Wisconsin was found comparable to that in other states. WT overlay thickness, joint spacing and pavement age were found to have significant effects on pavement performance.
Falling weight deflectometers