Bearing capacity assessment using FWD supplements maintenance management

The HELLER Ingenieurgesellschaft is starting the new year with adding bearing capacity assessments using the so-called Falling Weight Deflectometer (FWD) to its portfolio. In cooperation with the Institute of Road Engineering at Darmstadt University of Technology, HELLER carries out FWD measurements on airfield, industrial and public road pavements as a supplement to the traditional maintenance management.

Falling Weight Deflectometer (FWD)

The Falling Weight Deflectometer (FWD) is a dynamic method for assessing the bearing capacity by applying a force to the pavement using a falling weight - similar to the dynamic traffic load. The vertical deformation velocities of the surface, which are generated for a short time, are measured by geophones. Different evaluation and back-calculation methods allow the target value - based on the respective load class - to be compared with the actual value. In this way, not only the weakened areas can be identified, but also whether it is the bound and/or unbound layer of the pavement that is structurally impaired. The FWD method is non-destructive and delivers precise and reliable results in a short time, which can be used for assessing the pavement, analyzing possible causes of damage and for selecting suitable repair measures.

In contrast to the Pavement Condition Survey and Assessment (ZEB), in which the need for maintenance is determined by the condition of the road surface, the FWD also allows conclusions on the cause and effect relationship between the damage visible on the surface and the structural condition. The FWD can be used to first identify those areas with weak bearing capacity, followed by further analyses (e.g. drill cores). Bearing capacity assessments are thus an excellent extension of the ZEB, for example to determine the cause of damage or to select suitable maintenance measures.

Here are some impressions of the FWD demonstration by Marko Čičković at the HELLER premises:

Demonstration of the FWD at HELLER
Marko Čičković explains how the FWD works
Geophones for measuring deformation velocities
Presentation on the measuring method at HELLER