FDW Correlation Trial 2013

The trial was held in Bunschoten-Spakenburg on asphalt roads with a poor subgrade and on asphalt roads just south of Nijkerk, where the subgrade varied between moderate stiff to very stiff. The purpose of the trial was to determine -a- the repeatability of each FWD, -b- the FWD correlation factor of each FWD. Protocol 10 of CROW-report D11-07 Falling Weight Deflectometer calibration guide, August 2011, was used for the trial.

This report presents the structure of the trial, the test programme and test route and all common public results and data. The confidential FWD related data and results are reported in separate annexes submitted to the respective FWD users only. The report also touches on the accuracy and precision of the measurement of asphalt temperatures during the day of the trial.
All FWDs but two were capable of producing repeatable results. Only one of the participating FWDs failed to comply with the requirements set to the determination of the FWD correlation factor. As a result 14 out of the 16 participating FWDs met the specifications for obtaining the CROW FWD calibration certificate.