Ground penetrating radar (GPR) is a common tool for nondestructive testing of civil engineering materials, environment and agriculture. It allows rapid data collection and is widely used to measure or to estimate media parameters (pavements, bare agricultural fields, soils…).
Here, we are interested in roadways probed by GPR, in the context of wide band GPR such that the roughness of the pavement surface cannot be neglected anymore. Electromagnetic wave scattering from a rough interface leads to less energy being recorded by the receiver in the specular direction. This should be accounted for in order to accurately retrieve the EM (electromagnetic) properties of the sounded pavement.
The main goal of this study is to develop an improved asymptotic forward EM model for taking the roughness into account in order to invert GPR signals for the noninvasive quantification of pavement materials. This work will be compared with the classical model called Ament model , which has the advantage of being easily invertible. Its main advatage is that the main roughness parameter, the RMS (root-mean square) height, is easily retrieved. Nevertheless, its associated drawback is that it is independent on the surface auto-correlation, implying that it cannot be used to estimate the correlation length.
Thus, the aim of the study is to derive an asymptotic model that can be used to retrieve both the RMS (root mean square) height and the correlation length, by inverting synthetic or even real data. This may be a model sounded by physical considerations  or an empirical one based on simulation or measurement data. This model will be validated thanks to the reference use of a numerical method based on the method of moments .
 W. S. Ament, “Toward a theory of reflection by a rough surface,” Proceedings of the Institute of Radio Engineers, vol. 41, no. 1, pp. 142–146, 1953.
 T. Elfouhaily, C.A. Guérin, “A critical survey of approximate scattering wave theories from random rough surfaces,” Waves in Random Media, vol. 14, R1-40, 2004.
 C. Bourlier, N. Pinel, and G. Kubické, Method of Moments for 2D Scattering Problems: Basic Concepts and Applications, Wiley-ISTE, London, 2013.