This project developed and tested an automated portable device, using a low power pulsed electromagnetic wave detection technique, for determining asphalt pavement thickness and density during construction. The work involved antenna evaluation, software development, field data analysis and system specifications and prototype development. Three different antenna configurations were evaluated, and, based on performance data, a horn antenna was selected. Field data on a newly paved road section was collected to further test the antenna configurations, evaluate potential thickness accuracy, and to provide a data set for software development. A real-time prototype software was developed and tested on the field data. The antenna system was further improved with respect to electronic performance and packaging. Laboratory and field tests show that the device with the new horn antenna can accurately determine the dielectric constant of asphalt and can provide pavement thickness accuracy to within 0.2 inch. The test results also show a correlation of asphalt dielectric constant with its air content. An equipment manufacturer is collaborating with the contractor to explore the commercialization of the device.
The PDTM will enable agencies to maximize pavement life and minimize life cycle costs by accurately and completely determining, at the time of construction, if pavement has been built according to specifications. With this capability, agencies will be able to save millions of dollars in premature, unplanned and unnecessary repairs, and rehabilitation caused by inadequately constructed pavement. The proposed PTDM would be available at a price comparable to other pavement nondestructive testing devices; and thus would be applicable for routine use by contractors, state highway testing organizations, and by private and contracted testing laboratories. The final report is available from the National Technical Information Service (NTIS # PB2003-100546).
