Field Evaluation of a Non-Nuclear Density Pavement Quality Indicator

008125712001PDFTech ReportFHWA-CT-RD-2227-F-01-3CT-SPR-Study No. 2227Field testsMeasuring instrumentsHot mix asphaltAsphalt pavementsDensityDielectric propertiesNuclear density gagesCores (Specimens)Correlation analysisQuality assuranceHot mix asphaltNon-nuclear density gagesConnecticutConnecticut. Dept. of TransportationHenault, John W.Lane, Keith R.Sime, James M.Connecticut. Dept. of Transportation. Bureau of Engineering and Highway OperationsUnited States. Federal Highway AdministrationUS Transportation CollectionThe field performance of a non-nuclear density gauge was evaluated for measuring hot mix asphalt (HMA) pavement density. The gauge used is called the Pavement Quality Indicator (PQI) Model 300, invented and manufactured by TransTech Systems, Incorporated. The PQI's operation is based upon the density of asphalt being directly proportional to the measured dielectric constant of the material, i.e., the material's ability to store electrostatic energy per unit volume. Ten sites were selected from ongoing paving projects in Connecticut for use in the evaluation of the PQI Model 300 in the field. For comparison, nuclear density tests were performed at the same locations where PQI readings were taken. Finally, cores were drilled and tested according to AASHTO T-166. Based upon the results of the research study, it was concluded that poor correlation exists between PQI Model 300 instrument density and core density obtained in the field, as indicated by an average R-squared value of 0.28 for the ten sites evaluated. This poor correlation may be due to the presence of moisture introduced into the HMA during rolling operations. Quality assurance testing with the PQI Model 300 was not recommended.75