ABSTRACT
Regarding the bearing capacity of roads, there are many ways of gathering and analysing data. The Falling Weight Deflectometer (FWD) is a testing device, which has established itself over the past decades. But the FWD itself cannot give us an interpretation of the data gathered—naturally, there are many ways of analysing and interpreting the deflection bowl. Therefore, the purpose of this paper is to introduce German methods of analysing FWD data, which give a more indirect assessment of the structural condition of the pavement, and compare these methods with international methods (backcalculation of moduli). The added value of this paper regarding the current state of the art is the critical analysis of simplified two-layer-models and standard modulus back calculations.
Three pavement samples (asphalt), which moderate the comparison, are being utilised, distinguishable by the amount of traffic endured. These pavement samples are then analysed according to the three methods introduced.
The main finding is that a two-layer model and its individual assessment methods are simplifying the pavement structure. Consequently, the findings are rather simple. A three-layer model and the backcalculation of Young’s moduli gives further insight into the structure, but is prone to errors that derive from the uncertainties of the construction design data (e.g. thicknesses). This leads to the conclusion that a two-layer model may be too simple at first sight, but is to be seen as a concession to data uncertainties.
