Forensic Investigation of UTW Pavements

In 1997, the Florida Department of Transportation (FDOT) constructed an experimental ultra-thin whitetopping (UTW) test pavement at the Ellaville weigh station on I-10 in North Florida. This UTW pavement consisted of six test sections with varying panel dimensions and slab thicknesses. Polypropylene fibers were used in the concrete for three of the six test sections. The fiber content was specified as 3 lb per cubic yard of concrete. All asphalt surfaces were milled prior to concrete placement, and too much of the asphalt was removed in some areas resulting in remaining asphalt of only about 1 in. thick. The performance of these test sections was less than ideal, and some early cracking was observed on the concrete surface.

CTLGroup took part in a comprehensive investigation into the causes of these problems. The scope of the work included reviewing documents and collecting data, field testing and evaluation, laboratory testing, analyzing data, and preparing a final report. When the project was completed early in 2002, the investigators concluded that the UTW pavement had been underdesigned.