Falling Weight Deflectometer Testing/Evaluation Measurement of pavement structural properties via the falling-weight deflectometer (FWD) is an accepted practice in highway pavement testing. FWD’s are becoming more commonplace in the airport community. Despite the increasing popularity of FWD devices, the FAA does not currently issue specifications for their use on airport pavements. FAA Advisory Circular 150/5370-11: "Use of Nondestructive Testing Devices in the Evaluation of Airport Pavements" was issued in 1976 and has not been updated to include current FWD technology. Falling-weight deflectometers are often preferred over destructive methods of testing because they are much faster than destructive tests and do not entail the removal of pavement materials. In addition, the testing apparatus is easily transportable. Pavement properties are "back-calculated" from the observed dynamic response of the pavement surface to an impulse load (the falling weight). The disadvantage of the FWD method is that its results are often dependent on such factors as the particular model of tester used, the specific testing procedure, and the method of back-calculation. It is therefore in the interest of the airport community to develop a standardized set of procedures for FWD testing and analysis that is applicable to all of the major equipment manufacturers. Emphasis will be placed on verifying repeatability of FWD results, linearity of load impact, plate size and the development of improved back-calculation methods. Most data collected by the FAA's Falling Weight Deflectometer is populated into the National Airport Pavement Test Facility (NAPTF) database. The following link is for the NAPTF-FWD data introductory page, which leads to the FWD data search forms from tests performed in support of the NAPTF. Introduction to Falling Weight Deflectometer database The following software program is provided for backcalculation of FWD data. After downloading and unzipping the file, the setup file should be run to install the program on your computer. This software program is offered free of charge and accompanying documentation is currently being prepared. This software program is provided for evaluation purposes only. Note: For Windows 2000 Professional, you may need to install Service Pack 3 before you setup the backcalculation program.
FAA Backcalulation Software Program This program is furnished by the Government and is accepted and used by
the recipient with the express understanding that the United States
Government makes no warranties, expressed or implied, concerning the
accuracy, completeness, reliability, usability, or suitability of any
particular purpose of the information or the data contained in this
program or furnished in connection therewith, and the United States
Government shall be under no liability whatsoever to any person by reason
of any use thereof. This program belongs to the government. Therefore, the
recipient further agrees not to assert any proprietary rights therein or
to represent this program to anyone as other than a government program. The backcalculation software program is compressed in a Zip format. You can download a free evaluation copy of WinZip by clicking on the following image. The published documents listed below are in Adobe Acrobat (*.pdf) format and are available for download. You will need Adobe Reader software to view these documents. Adobe Reader is free and available for download. Analysis
of Nondestructive Test Data on Flexible Pavements Acquired at the National Pavement Test Facility Analysis
of Falling Weight Deflectometer Tests at Denver International Airport
Verification of Curling In PCC Slabs At FAA National Airport Pavement Test Facility Comparison Between Falling Weight
Deflectometer and Static Deflection Measurements on Flexible Pavements at
the National Airport Pavement Test Facility (NAPTF) Contact Project Lead: Dr. Gordon Hayhoe Last Update: 08/21/2006 |