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Falling Weight Deflectometer

Recently started Structural analysis testing for road pavement ( Rigid and Flexible ) using falling weight deflectometer . Our unit is vehicle mounted and hence easy to get more and most reliable deflection output.

Falling Weight Deflectometer

Main features for the FWD test with our VMFWD are :

  • Falling Weight Deflectometer ( FWD ) is a device which drops specified load, controlled by the operator, onto a circular plate positioned on the pavement surface wheel path and measures the deflection of the pavement with seven sensors. These sensors are spaced at specified distance usually 30 cm apart in a series along the device with one sensor located directly over the point of loading. Deflection is measured in micro-meter.
  • Based on the FWD deflection measurements, strength of pavement, elastic layer strength, finite element analysis, or other mathematical modeling techniques can be applied to estimate the resilient modulus, modulus of elasticity, remaining life of surface layer or other factors for the pavement, sub-base, and sub-grade layers. These values can be used to estimate the remaining structural capacity of the existing pavement and determine any additional requirement of structural overlay.
  • Processed data from Ground Penetrating Radar (GPR) measurement. Layerboundaries, material types and information about the accuracy of the processing.
  • Deflections from KUAB FWD measurement, raw data or normalized deflections.
  • Other data from KUAB FWD measurement. Load, temperature, time and a few standardized parameters from visual inspection made during the FWD measurement.
  • General numerical data. Any numerical data, for example friction, visual observations may separately be worked out from other program.
  • All structural analysis from fwd deflection and other input from FWD is used for output from KUAB PVD FWD Analysis Programs.
  • Falling Weight Deflectometer

    Analysis features

     

    There are No. of different FWD data analysis programs in the our software package:

  • Subdivision, to make subsections with homogeneous bearing capacity or input parameters.
  • NOR Axle load, to calculate the axle load that the pavement is expected to be able to cope with.
  • FIN Empirical overlay, calculating overlay based on center deflection only, with a method similar to old Benkelman Beam approach.
  • OVER Moduli and overlay, calculating layer moduli, expected lifetime and suggested overlay, based on strain criteria. The program uses the method of equivalent thickness.
  • RIGID axle load, checking the strength of PCC road pavements.
  • OVERCALC, calculating layer moduli, expected lifetime and suggested overlay, based on strain criteria. The program uses linear elasticity theory.
  • PCN Flexible, PCN Rigid and PCN composite, calculating PCN for flexible, rigid and a certain type of composite pavements, and suggesting what the pavement should have been to reach a certain PCN.
  • Joint transfer, calculating the ratios between deflections from different sensors, for example to illustrate deflection transfer over joints.
  • The rates for testing are most reasonable and output is with the latest version of computer program from KUAB.