Evaluation of Homogeneity of Thickness of New Asphalt Layers Using GPR

Abstract

The use of GPR (Ground Penetrating Radar) as an auxiliary tool in assessing the structural condition of the road pavement is now a common practice. Such equipment is employed by both private consulting companies and main road management laboratories. The field of application of GPR is constantly growing. Radar techniques are combined with sophisticated methods of data analysis, which facilitates the process of assessment of damage to the pavement structure, such as cracks, inhomogeneity of compaction or the condition of interlayer connections. The primary role of GPR operators is to determine the thickness of layers, including new ones. This article discusses the main elements of the method of measuring the thickness of new asphalt layers. This method can support the acceptance testing phase. Particular attention is attached to the methods for the calibration of the wave travel velocity, including the role of reference drill holes, their precise positioning and determination of layer thickness. The article revolves around the dispersion of measurements and uncertainty of average and local results, as well as pointing to the key factors having an influence over accuracy, which is of importance in the consecutive phases of acceptance testing.