TU1208 open database of radargrams. the dataset of the IFSTTAR geophysical test site

This paper aims to present a wide dataset of ground penetrating radar (GPR) profiles recorded on a full-size geophysical test site, in Nantes (France). The geophysical test site was conceived to reproduce objects and obstacles commonly met in the urban subsurface, in a completely controlled environment; since the design phase, the site was especially adapted to the context of radar-based techniques. After a detailed description of the test site and its building process, the GPR profiles included in the dataset are presented and commented on. Overall, 67 profiles were recorded along eleven parallel lines crossing the test site in the transverse direction; three pulsed radar systems were used to perform the measurements, manufactured by different producers and equipped with various antennas having central frequencies from 200 MHz to 900 MHz. An archive containing all profiles (raw data) is enclosed to this paper as supplementary material. This dataset is the core part of the Open Database of Radargrams initiative of COST (European Cooperation in Science and Technology) Action TU1208 “Civil engineering applications of Ground Penetrating Radar”. The idea beyond such initiative is to share with the scientific community a selection of interesting and reliable GPR responses, to enable an effective benchmark for direct and inverse electromagnetic approaches, imaging methods and signal processing algorithms. We hope that the dataset presented in this paper will be enriched by the contributions of further users in the future, who will visit the test site and acquire new data with their GPR systems. Moreover, we hope that the dataset will be made alive by researchers who will perform advanced analyses of the profiles, measure the electromagnetic characteristics of the host materials, contribute with synthetic radargrams obtained by modeling the site with electromagnetic simulators, and more in general share results achieved by applying their techniques on the available profiles

Combining NDT tools for analysing the efficiency of repair techniques of wharves: the MAREO project

ISBN: 9780415669863Repair of structures in concrete is still a challenge, especially when access and environment offer a difficult context such as the case of wharves. Concerning the repair of concrete for marine structures, European standards give the requirements in predefined and standardised conditions. However, repair of wharves is performed in harsh conditions such as access, humidity and operator position. These conditions do not enable the direct application of standards. By accounting for these requirements, the repair technique consists in rebuilding the concrete cover and in some cases using protective coating for some beams. In this paper, we focus on the concrete repair techniques. The aim of MAREO project (French project of the National competitive cluster in Civil Engineering and Eco-Building) is to compare several repair techniques carried out in the most complex area for repair: the tidal zone. The project deals with initial performance, sustainability, cost of durability and concrete properties monitoring by Destructive Testing (DT) and Non-Destructive Testing (NDT) techniques. The studied NDT techniques are: impact-echo, surface waves, multi-offset radar, and capacitive method. Both, beams placed in natural exposure and slabs specimens placed in accelerated conditions in laboratory are considered. For all the beams, the contaminated concrete was removed using high-velocity water jets (hydro-demolition). The selected techniques are wet shotcrete, dry shotcrete, formed concrete and manual repair. This paper focuses on the ability of NDT techniques to evaluate the changes of properties related to the chloride ingress in concrete both on site and in accelerated laboratory conditions. The interest of each technique and its sensitivity to several physical factors are highlighted. The need of NDT-combination is illustrated

Comparison of durability indicators obtained by Non Destructive Testing methods to monitor the durability of concrete structures

International audienceThis paper deals with the use of non destructive testing methods (NDT) to assess indicators of concrete durability and mechanical properties of reinforced concrete structures. On site, NDT methods based on electromagnetic or ultrasonic wave propagation (such as radar, impact echo, ultrasonic transmission deviceÉ) are used because they are more or less sensitive to water content and mechanical properties depending on the method. It has been shown, in a former project [1, 2], that the NDT results called Òobservablesî are linked to mechanical and durability indicators (YoungÕs modulus, compressive strength, porosity and saturation degree). Meanwhile, the relationship between observables and indicators depends on the concrete mix design. A calibration protocol is then proposed to get this relationship for the right mix of the reinforced structure studied by using a minimal number of cores. The cores are non-destructively characterised in laboratory or used to determined reference indicators by standardised destructive methods. The aims of this paper are first to present the ND calibration protocol on cores and then to validate this proposed calibration protocol. To achieve this goal, some NDT results obtained on site and on the corresponding core are compared and durability indicators deduced from NDT calibration are compared with reference durability indicators

COST Action TU1208 – Working Group 2 – GPR surveying of pavements, bridges, tunnels and buildings; underground utility and void sensing

This work aims at presenting the main results achieved by Working Group (WG) 2 "GPR surveying of pavements, bridges, tunnels and buildings; underground utility and void sensing" of the COST (European COoperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar" (www.GPRadar.eu, www.cost.eu). The principal goal of the Action, started in April 2013 and ending in October 2017, is to exchange and increase scientific-technical knowledge and experience of Ground Penetrating Radar (GPR) techniques in civil engineering, whilst promoting throughout Europe the effective use of this safe non-destructive technique. The Action involves more than 300 Members from 28 COST Countries, a Cooperating State, 6 Near Neighbour Countries and 6 International Partner Countries

Méthodes d'évaluation et contrôle non destructif et de géophysique

Zerstörungsfreie (ND) Erkundungstechniken, seien es nun zerstörungsfreie oder geophysikalische Bewertungsmethoden, werden üblicherweise im Bau- und Transportwesen, im Bereich der Energietechnik oder der Stadtentwicklung angewandt. Während sich jedoch im Laufe der letzten Jahrzehnte das Interesse auf interne geometrische Informationen zu der untersuchten Umgebung richtete, konzentrieren sich jüngere Forschungen auf Informationen, die mit der Art und dem Zustand dieser Umgebung verbunden sind, um so dem Begiff der zerstörungsfreien Bewertung näher zu kommen. Die gegenwärtig laufenden Studien versuchen, die aus zerstörungsfreien Messungen abgeleiteten Werte in statistische, mit Lebensdauermodellen verknüpfte Ansätze zu integrieren.Les techniques de reconnaissance non destructives (ND) sont couramment employées pour le génie civil des transports, de l'énergie ou du domaine urbain, que l'on parle de méthodes d'évaluation et contrôle non destructif ou de géophysique. Si dans les dernières décennies, on s'intéressait à des informations géométriques internes du milieu ausculté, les recherches récentes se sont orientées vers des informations liées à la nature et l'état de ce milieu pour tendre vers une notion d'évaluation non destructive. Actuellement, les études en cours cherchent à intégrer les valeurs déduites des mesures ND dans des approches statistiques associées à des modèles de durée de vie

GPR Monitoring of Artificial Debonded Pavement Structures throughout Its Life Cycle during Accelerated Pavement Testing

The paper gives an overview of a ground penetrating radar (GPR) experiment to survey debonding areas within pavement structure during accelerated pavement tests (APT) conducted on the university Gustave Eiffel’s fatigue carrousel. Thirteen artificial defect sections composed of three types of defects (Tack-free, Geotextile, and Sand-based) were embedded during the construction phase between the top and the base layers. The data were collected in two stages covering the entire life cycle of the pavement structure using four GPR systems: An air-coupled ultra-wideband GPR (SF-GPR), two wideband 2D ground coupled GPRs (a SIR-4000 with a 1.5 GHz antenna and a 2.6 GHz-StructureScan from GSSI manufacturer), and a wideband 3D GPR (from 3D-radar manufacturer). The first stage of the experiments took place in 2012–2013 and lasted up to 300 K loadings. During this stage, the pavement structure presented no clear degradation. The second stage of experiments was conducted in 2019 and continued until the pavement surface demonstrated a strong degradation, which was observed at 800 K loadings. At the end of the GPR experiments, several trenches were cut at various sections to get the ground truth of the pavement structure. Finally, the GPR data are processed using the conventional amplitude ratio test to study the evolution of the echoes coming from the debonded areas

Méthodes d'évaluation et contrôle non destructif et de géophysique

Zerstörungsfreie (ND) Erkundungstechniken, seien es nun zerstörungsfreie oder geophysikalische Bewertungsmethoden, werden üblicherweise im Bau- und Transportwesen, im Bereich der Energietechnik oder der Stadtentwicklung angewandt. Während sich jedoch im Laufe der letzten Jahrzehnte das Interesse auf interne geometrische Informationen zu der untersuchten Umgebung richtete, konzentrieren sich jüngere Forschungen auf Informationen, die mit der Art und dem Zustand dieser Umgebung verbunden sind, um so dem Begiff der zerstörungsfreien Bewertung näher zu kommen. Die gegenwärtig laufenden Studien versuchen, die aus zerstörungsfreien Messungen abgeleiteten Werte in statistische, mit Lebensdauermodellen verknüpfte Ansätze zu integrieren.Les techniques de reconnaissance non destructives (ND) sont couramment employées pour le génie civil des transports, de l'énergie ou du domaine urbain, que l'on parle de méthodes d'évaluation et contrôle non destructif ou de géophysique. Si dans les dernières décennies, on s'intéressait à des informations géométriques internes du milieu ausculté, les recherches récentes se sont orientées vers des informations liées à la nature et l'état de ce milieu pour tendre vers une notion d'évaluation non destructive. Actuellement, les études en cours cherchent à intégrer les valeurs déduites des mesures ND dans des approches statistiques associées à des modèles de durée de vie

Comparative measurements of ground penetrating radars used for road and bridge diagnostics in the Czech Republic and France

The paper describes the current situation regarding the comparative measurement and accuracy of ground penetrating radars (GPR). GPR measurements are used for non-destructive diagnostic of roads and bridges, specifically for measuring pavement layer thickness and determining the location and position of reinforcement in concrete. The information used in the paper is based on the performed in-situ measurements. The conclusion includes recommendations of how to perform and evaluate the in-situ GPR comparative measurements

Supplementary Files: TU1208 Open Database of Radargrams: The Dataset of the IFSTTAR Geophysical Test Site

<p>Supplementary Files: TU1208 Open Database of Radargrams: The Dataset of the IFSTTAR Geophysical Test Site</p