The Loadman portable falling weight deflectometer (FWD) which has been introduced to the New Zealand market in relatively recent times (1996), is described. It shows significant potential as a very useful tool for the pavement engineering practitioner, particularly since the AUSTROADS pavement design procedures were adopted by Transit New Zealand in 1995.
The research was carried out in 1997–98. This report of the research describes methods of improving the utilisation of the Loadman by developing revised constants that better reflect factors such as the loading configuration and material response. These constants can be programmed into the device.
The report also describes the development of Loadman test procedures for both field and laboratory-based tests. The laboratory version of the test allows anisotropic elastic modulus data to be obtained using simple and cost-effective procedures. Verification of the laboratory Loadman testing and analysis procedure has been carried out using finite element modelling.
In addition, the results of laboratory Loadman tests have been compared with data obtained using repeated load triaxial (RLT) tests. The analysis shows that the two test procedures correlate reasonably well although the level of stress imposed by the Loadman may be greater than that occurring in-service, especially for subgrade soils.
Keywords: elastic modulus, falling weight deflectometer, FWD, New Zealand, pavement, pavement design, road, subgrade, testing