Structural analysis

A road is more than just a trafficked surface; there is a whole structure underneath. A road structure is usually composed of a subgrade soil, a subbase, a base, and a surfacing. Each course has a specific function: frost resistance, drainage, bearing capacity, etc.

The quality of a road structure can be characterized by its bearing capacity and residual life. Using deflection measurements, a thorough knowledge of the thicknesses of the various courses in the road structure and past, present and future loading by heavy traffic as inputs, advanced models can make reasonable estimates of the elastic moduli of the various courses and of the time that remains before structural problems will appear.

BRRC is equipped with to vehicles for non-destructive deflection measurements under all circumstances: a falling weight deflectometer (FWD) and a curviameter. Much care is taken to use both devices correctly. This includes the calibration of the geophones, i.e., the sensors capable of recording the deflection of a road structure under loads. BRRC has the necessary equipment to calibrate the geophones of the FWD entirely on its own and is able to offer its services to any owner of an FWD of the same brand. Comparative tests with different FWD units are occasionally made. A comparative test day is organized every two years by CROW in the Netherlands and TRL in the United Kingdom.

BRRC remains actively involved in research to draw as much information as possible from results of measurements. In this context attention is paid to the use of the FWD in situations which are rather uncommon at an international level, relations are sought between the deflection bowl of the curviameter and the properties of the lower courses in a road structure, and comparative measurements are made with the FWD and the curviameter.

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