Portable Falling Weight Deflectometer


This is a light portable device for the measurement of Deflections. The device is easy to handle and can be used on all construction sites and all materials under any condition. It makes possible to measure bearing capacity and compaction ratio of construction layers and constructions in places where other measuring devices cannot be used owing to their size or because of the necessity to use a lorry or a van as a weight and or transportation unit. LOADMAN is also provided with an internal memory and with a keyboard. The data can be transferred to PC via USB connection.

Measuring principle

The deflection caused by the load of a falling weight is measured by an accelerometer. The acceleration is double integrated and thus the deflection can be calculated. The measuring results are given as the maximum deflection, the calculated bearing capacity modulus E, the length of the loading impulse and the percentage (approx.) of the rebound deflection compared to the maximum deflection as well as the compaction ratio, that is the ratio of the second and further on deflections compared to the first measured deflection (effectiveness of compaction).

Range of use

Technically the device can be used on practically all kinds of construction sites to measure bearing capacity and for compaction control on bound, unbound, and special layers; for example, on roads, streets, bridge sites, house building sites, in trenches, on sports fields (football, baseball, tennis, golf, athletics etc.) as well as for laboratory tests of various kinds of materials.


  • Total weight: 16 kg
  • Height:117 cm
  • Diameter: 13 cm
  • Diameter of loading plate(s): 132 mm, 200 mm and 300 mm (option)
  • Falling weight: 10 kg
  • Falling height: 80 cm
  • Operating voltage: 27 V (3 × 9V batteries)
  • Measuring range: 0.1-5 mm approx.
  • Length of loading/unloading impulse: 25-30 ms approx.

Heavy Weight Deflectometer (HWD)

HWD is used to measure deflection of thick highway pavement. The device mounted on a two-axle trailer designed especially for determining structural information of heavy-duty type pavements. The device has Hydraulic Breaker, 2-Cylinder 18 Horse Power gasoline engines with 12-volt Alternator permits high speed and independent operation of the tow vehicle by 4 drop automated sequence in 30 seconds, data capture from 1-35 drops at each location with up to 35 forces.