Ground Penetrating Radar (GPR) is extremely useful in producing high-resolution images of the subsurface, typically from 0 to 10 m depth, through wide-band nonsinusoidal electromagnetic waves. The employed frequencies range from 10 MHz to 4 GHz. This survey method is effective, rapid, nondestructive and noninvasive. In fact, GPR has become an established and powerful tool for the inspection of road and highway pavements, bridges, tunnels, and for detecting subsurface cavities and voids. It is also used to perform detailed quality controls of reinforced concrete, analysis of geological structures, mapping of soil, rock or fill layers in geotechnical investigations, foundation investigations, besides being a valuable monitoring technique of buried utilities such as conduits, electricity cables, gas and water pipes.

In the presence of a complex scenario, an accurate electromagnetic forward solver is a fundamental tool for the interpretation of GPR data. It can be used by GPR operators to identify the signatures generated by targets, especially in the case of uncommon objects or multiple structures. It can also be employed to perform repeated evaluations of the scattered field due to known targets, in combination with optimization techniques, in order to estimate – through comparison with measured data – the physics and geometry of the region investigated by the GPR. An electromagnetic forward solver can be used as a preliminary step that precedes a survey, or else to gain a posteriori a better understanding of the collected experimental results.

To obtain the best results, GPR has to be correctly applied by qualified personnel, familiar with both the physical principles of the method and its limitations. The interpretation of resultant data is a difficult problem and should be carried out consciously and carefully, combining the relevant information of above ground and subsurface features.

In this framework, the Session is concerned with the state of art, research activity, and progress of GPR techniques in civil engineering. In particular, novel GPR instrumentation will be presented. The outcomes of performed surveys will be reported. How to correctly plan experimental campaigns and conduct field measurements will be discussed. Direct and inverse electromagnetic scattering techniques will be a subject of interest. Data processing methods and approaches for the interpretation of results will be proposed. Trade-offs between GPR and other nondestructive testing techniques will be considered. The merits and limitations of current GPR systems in various civil engineering applications will be highlighted.

This Session is held since 2011. Since 2014 it is co-organised by COST (European COoperation in Science and Technology), via the Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar." The COST Action TU1208 focuses on the exchange of scientific-technical knowledge and experience of GPR techniques in civil engineering applications, aiming as well at promoting a wider and more effective use of this inspection method throughout the Europe. The scientific activities of the Action are being developed within the frame of a unique approach based on the integrated contribution of University researchers, software developers, geophysics experts, nondestructive testing equipment designers and producers, end users from private companies and public agencies. More than 150 Institutions from 29 COST Member Countries (Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Ireland, Israel, Italy, Latvia, Malta, Macedonia, The Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom) and 6 COST Near Neighbour Countries (Albania, Armenia, Egypt, Jordan, Russia, Ukraine), have already joined the Action. Moreover, Institutions from Australia, Colombia, Hong Kong, Philippines, Rwanda and U.S.A. have joined the Action, too. For further information concerning COST Action TU1208, please visit www.GPRadar.eu or take contact with the conveners of this Session. For more information about COST, please visit www.cost.eu.