Falling Weight Deflectometer

The load test is executed with the Falling Weight Deflectometer (FWD). This equipment applies an impact load, on the pavement surface, resultant from the drop off a mass at a certain height. It is a nondestructive assay and the vertical displacements of the pavement surface induced by the load are measured in several points, through the geophones.

The equipment is from DYNATEST, model HWD Heavy Weight Deflectometer 8081, and in addition to measuring the applied force and displacements, it is able to determine and refer the location of each point with geodesic coordinates by means of the GPS (Global Position System). The pavement surface temperature is assessed with infrared thermometer.

It is possible to change the distance between the nine geophones according to the pavement structure. The speed of the applied force simulates a vehicle at 60 – 80 km/h, transmitted by a 300 or 450 mm diameter plate. Through 4 different fall heights, and variation of the falling mass value, it is possible to obtain impact forces between 15 and 240 kN.