Standard Recommended Practice for
Calibrating the Load Cell and Deflection Sensors for a
Falling Weight Deflectometer
AASHTO Designation: R 32-03 (2008)1
1.1.This practice covers the reference calibration of the load cell and the deflection sensors and the relative calibration of the deflection sensors of a falling weight deflectometer (FWD). It is used to establish calibration factors for correcting FWD measurements.
1.2.This procedure is not applicable to the calibration of cyclic loading and other types of pavement deflection testing equipment.
1.3.Reference calibration is performed at least once per year, or as soon as possible after a deflection sensor or a load cell has been replaced on the FWD.
1.4.Relative calibration is performed on the deflection sensors at least once per month and immediately after a deflection sensor is replaced.
1.5.The procedure results in calibration factors that are entered into the FWD software as multipliers.
When the FWD measurements are multiplied by the calibration factors the result is a set of measurements that have been corrected to agree with the calibration instrumentation.
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