Deflection sensors are used to measure the deformation of the pavement in response to the load pulse.

Data are acquired from various sensors for use in post-test analysis of pavement properties. The load pulse is produced by dropping a large weight onto a 'buffer' which shapes the pulse, and then transmitted to the pavement through a circular load plate. Comprehensive road survey vehicles typically consist of a FWD mounted on a heavy truck together with a ground-penetrating radar and impact attenuator.ĭuring testing, a FWD subjects the pavement surface to a load pulse which simulates the load produced by a rolling vehicle wheel. Depending on its design, a FWD may be contained within a towable trailer or it may be built into a self-propelled vehicle such as a truck or van. The data acquired from FWDs is primarily used to estimate pavement structural capacity, to facilitate overlay design or determine if a pavement is being overloaded. Finally, the study aims to validate the established criteria by conducting in-situ case study.A falling weight deflectometer, towed by a truckĪ falling weight deflectometer (FWD) is a testing device used by civil engineers to evaluate the physical properties of pavement in highways, local roads, airport pavements, harbor areas, railway tracks and elsewhere. Therefore, the main objective of this paper was to discuss the distribution features of dynamic deflection basins of asphalt pavements with crack distresses, and present the reasonable criteria to filter the testing data of FWD deflection basins. Identifying effective data of dynamic deflection basins seems to be an important task for performing modulus backcalculation. A review of the currently used backcalculation procedures indicates that the calculation is generally based on a homogeneous, continuous, and linear elastic multi-layer system. FWD backcalculation is mathematically an inverse problem that could be solved either by deterministic or by probabilistic approach. With the popularization of falling weight deflectometer (FWD) to calculate the stiffness related parameters of the pavement structures, non-destructive evaluation of physical properties and performance of pavements has taken a new direction.

Fwd backcalculation