Wenting Liu

Application of the Texas Department of Transportation Continuous Deflection Device to Select Rehabilitation Strategies for Concrete Pavements

In 2013, the Texas Department of Transportation completed development of its total pavements acceptance device (TPAD), which contains the next generation of rolling deflectometer integrated with ground penetrating radar and video logging. TPAD collects data at 2 mph and provides deflections measurement at 2-in. intervals from three rolling geophones. In this paper, the development of TPAD is described with typical outputs from the data processing software. How TPAD deflections can be used to determine the load transfer efficiencies of joints and cracks is described, along with the correlation with falling weight deflectometer measurements. Four case studies are presented illustrating typical TPAD data on a range of problem concrete pavements in Texas. These case studies include pavements with a debonded concrete overlay, pavements with voids beneath the slab, and a section that has full-depth patching. The TPAD data collected on US-75, which is a jointed concrete pavement in very poor condition, are presented. TPAD provides highly useful data for planning the rehabilitation of concrete pavements in Texas. Since its development, TPAD has been used on 15 major rehabilitation projects. A popular application is to determine if an upcoming project is a good candidate for an engineered thin asphalt overlay or if more major structural improvements are required.