3D modelling of asphalt concrete overlay based on GPR data

For proper rehabilitation planning and appropriate technology selection for airport pavements, information on the layer thicknesses is important. Pavement layer thickness can be determined by ground penetrating radar (GPR). GPR data is usually displayed in distance vs thickness diagrams. These two-dimensional displays do not utilise the full potential of the three-dimensional (3D) information of GPR data. To appropriately represent the data, the display should be 3D, as well. The aim of this study is to present a process for creating a 3D model and spatial representation of asphalt concrete (AC) overlay thickness. The 3D model of the AC overlay surface is generated based on the Delaunay triangulation of interpreted GPR data. The 3D model is presented on contour and band maps, whose accuracy is evaluated by comparing the thicknesses displayed by the contour maps with those measured in core samples. The calculated mean relative error of the contour map is 7.2%. The band map is used to identify sections of equal thickness or to analyse predefined sections, to select the appropriate rehabilitation technology. The combination of the interpreted GPR data and Delaunay triangulation successfully compensates for the lack of 3D GPR, in terms of the spatial representation of layer thickness.