Abstract: A falling weight deflectometer (1) comprising a load plate (2) adapted to engage a test surface, force transmission means adapted to transmit a force to the load plate (2), buffer means (19), a drop weight (8). The drop weight (8) is adapted to impact said force transmission means via said buffer means (19) so as to provide a force to be transmitted to said load plate via said force transmission means. The falling weight deflectometer further comprises at least one linear electric motor (15) for lifting said drop weight (8) to a predetermined height above said force transmission means.

Abstract: A method and an apparatus for rolling wheel deflection measurement are disclosed. The apparatus includes a rolling wheel to be moved along a measuring surface in a first direction; a frame extending essentially along the measuring surface in the first direction from at least the rolling wheel; four spaced apart range sensors; a scanner for scanning in a first time interval a number of lines using each of the range sensors, so as to get a corresponding number of virtual images, in which the pixel values represent distances; and a data processor adapted for comparing and matching the virtual images, so as to identify corresponding regions, and for calculating a deflection value using matched pixel values of virtual images from the virtual images based on the identification corresponding regions.

Abstract: A falling weight deflectometer is disclosed. The falling weight deflectometer includes a load plate adapted to engage a test surface, a force transmitter adapted to transmit a force to the load plate, a buffer, and a weight adapted to impact the force transmitter via said buffer so as to provide a force to be transmitted to the load plate via the force transmitter. A guide is included for guiding the weight towards the force transmitter, and a lifting device is included for lifting the weight to a height above the force transmitter. The lifting device includes an electric motor to drive a threaded spindle in engagement with the weight.

Abstract: A method and an apparatus for rolling wheel deflection measurement are disclosed. The apparatus includes a rolling wheel to be moved along a measuring surface in a first direction; a frame extending essentially along the measuring surface in the first direction from at least the rolling wheel; four spaced apart range sensors; a scanner for scanning in a first time interval a number of lines using each of the range sensors, so as to get a corresponding number of virtual images, in which the pixel values represent distances; and a data processor adapted for comparing and matching the virtual images, so as to identify corresponding regions, and for calculating a deflection value using matched pixel values of virtual images from the virtual images based on the identification corresponding regions.

Abstract: The present invention directed to rolling weight deflectometers having sensors to measure pavement deflection, and to provide test data to determine the subgrade modulus and equivalent thickness of pavements. This information is then utilized to determine more than deflection and according to the present invention is utilized to determine critical strain parameters that can be applied to predict bearing capacity, rutting and roughness characteristics of pavements. This invention enhances the value of pavement testing while at the same time allowing for testing systems having fast moving wheel loads. The collected data can be used to determine vertical compressive strain and horizontal tensile strain, which can be more valuable for the prediction of remaining life time and recommendations for repair and maintenance.

Abstract: Systems and methods are disclosed that provide improved non-destructive testing of pavements and in particular non-destructive testing of pavements using rolling wheel deflectometer systems having more than four sensors. The additional sensors more accurately detect pavement deflections under load by compensating for the influence the load deflection basin can have on sensors beyond those at the wheel load. The sensors should be spaced with equal distances from the rolling weight and can have a distance between adjacent sensors that is greater than the equivalent thickness of the pavement being measured.