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

Ground-penetrating radar as a tool to detect rock heterogeneities (channels, cemented layers and fractures) in the Luxembourg Sandstone Formation (Grand-Duchy of Luxembourg)

A combined study of radar profiles and thin section analysis supported by modelling of synthetic radar traces reveals that ground-penetrating radar (GPR) reflections generated in diagenetically altered sandstones cannot always be interpreted unequivocally. This is illustrated in the Luxembourg Sandstone Formation, which has been altered diagenetically by selective carbonate cementation and fracturing. Cemented lenses and concretions developed along the bedding planes, especially at places with high primary carbonate content. Cementation resulted in the alternation of cemented carbonate-rich sandy layers (thickness 30-50 cm and variable length) and uncemented carbonate-poor sandstone layers. The ability of GPR to detect the geometry of these lenses and vertical fractures with centimetre apertures has been tested at several antenna frequencies (100, 200, 250 and 500 MHz). Relative dielectric permittivity calculations were carried out to assess variations of this electric property within the cemented and uncemented layers as a function of porosity, calcite and water content in the pores. Two-dimensional full waveform modelling was also carried out to study the effect of conductivity in the sandstones and the effect of interlayer clay seams. At the penetration depth of the radar (7 m with 250 MHz), cemented lenses and concretions could only be detected with GPR when the porosity contrast was sufficiently high, which is not always the case. This conclusion is supported by the modelling. The data also proved the ability of radar to detect large open vertical fractures along which sandstones are weathered. The study has implications for investigations which will use GPR to detect three-dimensional distribution of diagenetic pore filling precipitates as well as secondary porosity development along fractures

Influence of air conditioning management on heat island in Paris air street temperatures

International audienceProjections of future climate suggest increases in extreme temperatures particularly in mid latitudes. In addition, the effect of heat waves, which are becoming a major “summer killer”, is exacerbated in urban areas owing to the heat island effect. Air conditioning (A/C) is a key parameter for health problems in case of heat waves since, on one hand, it reduces mortality but, on the other hand, depending on the heat management, it can increase street temperature therefore increasing the air cooling demand. Results of a meso-scale meteorological model (MESO-NH), coupled to an urban energy balance model including a simplified building model (TEB), are used. Simulations based on a realistic spatial cartography of air-cooled chillers and cooling towers in the city of Paris and surroundings have been performed. The simulation period corresponds to the extreme heat wave in Paris: 9–13 August 2003. Five scenarios will be discussed: firstly a baseline without air-conditioning (NO-AC scenario); secondly the actual situation including individual air dry coolers, wet cooling towers and an urban cooling network relying on free-cooling (water-cooled A/C with the river Seine) (REAL scenario). A third scenario will assume that all the heat is rejected as sensible heat in the atmosphere (DRY AC scenario). Two other scenarios correspond to a prospective where A/C is doubled. Scenario 4 assumes that all the heat is rejected as sensible heat in the atmosphere (DRY ACx2 scenario). On the opposite, scenario 5 assumes that all the heat is rejected underground or in the river Seine (NOREJ scenario). Results show that A/C affects the UHI depending on its management. A detailed analysis on selected districts shows that the local temperature variation resulting from heat island is proportional to the sensible heat rejected locally by A/C, indicating that a clever A/C management is all the more important to provide comfort and to mitigate heat island. Moreover, the incidence of the sky view factor is also discussed

Recycling of road materials into new unbound road layers - Main practice in selected European countries

Most European countries are active in the field of recycling road materials, but knowledge and practice differ between countries. The European project DIsmantling and RECycling Techniques for road MATerials - Sharing knowledge and practices aims at sharing knowledge and practice in this field among the 15 participating countries, with the view of drafting European best-practice guidelines. This paper reports on the first step towards this goal, which consists of summarising documented practices within these countries concerning demolition and recy- cling of road materials back into new unbound road layers. Common documented practice and major differences between European countries are highlighted and put in perspective, thanks to a broader international document review

GPR System Performance Compliance According to COST Action TU 1208 Guidelines

Ground Penetrating Radar (GPR) systems shall be periodically calibrated and their performance verified, in accordance with the recommendations and specifications of the manufacturer. Nevertheless, most GPR owners in Europe employ their instrumentation for years without ever having it checked by the manufacturer, unless major flaws or problems become evident, according to the results of a survey carried out in the context of COST (European Cooperation in Science and Technology) Action TU1208 “Civil engineering applications of Ground Penetrating Radar.” The D6087–08 standard, emitted by the American Society for Testing Materials (ASTM International), describes four procedures for the calibration of GPR systems equipped with air-coupled antennas. After a critical analysis of those procedures, four improved tests were proposed by a team of Members of the COST Action TU1208, which can be carried out to evaluate the signal-to-noise ratio, short-term stability, linearity in the time axis, and long-term stability of the GPR signal. This paper includes a full description of the proposed tests and presents the results obtained by scientists from Belgium, Czech Republic, Portugal, and Serbia, who executed the tests on their GPR systems. Overall, five pulsed control units and nine antennas were tested (five horn and four ground-coupled antennas, with central frequencies from 400 MHz to 1.8 GHz). While the performed measurements are not representative enough to establish absolute thresholds for the tests, they provide a valuable indication about values that one could obtain when testing GPR equipment, if the equipment is working reasonably well. Moreover, by periodically repeating the tests on the same equipment, it is possible to detect any significant shift from previously obtained values, which may imply that the GPR unit or antenna under test is not working in a normal or satisfactory manner. We also believe that executing the tests described in this paper is a useful exercise to gain awareness about the behaviour of a GPR system, its accuracy and limits, and how to best utilize it.Ground Penetrating Radar (GPR) systems shall be periodically calibrated and their performance verified, in accordance with the recommendations and specifications of the manufacturer. Nevertheless, most GPR owners in Europe employ their instrumentation for years without ever having it checked by the manufacturer, unless major flaws or problems become evident, according to the results of a survey carried out in the context of COST (European Cooperation in Science and Technology) Action TU1208 “Civil engineering applications of Ground Penetrating Radar.” The D6087–08 standard, emitted by the American Society for Testing Materials (ASTM International), describes four procedures for the calibration of GPR systems equipped with air-coupled antennas. After a critical analysis of those procedures, four improved tests were proposed by a team of Members of the COST Action TU1208, which can be carried out to evaluate the signal-to-noise ratio, short-term stability, linearity in the time axis, and long-term stability of the GPR signal. This paper includes a full description of the proposed tests and presents the results obtained by scientists from Belgium, Czech Republic, Portugal, and Serbia, who executed the tests on their GPR systems. Overall, five pulsed control units and nine antennas were tested (five horn and four ground-coupled antennas, with central frequencies from 400 MHz to 1.8 GHz). While the performed measurements are not representative enough to establish absolute thresholds for the tests, they provide a valuable indication about values that one could obtain when testing GPR equipment, if the equipment is working reasonably well. Moreover, by periodically repeating the tests on the same equipment, it is possible to detect any significant shift from previously obtained values, which may imply that the GPR unit or antenna under test is not working in a normal or satisfactory manner. We also believe that executing the tests described in this paper is a useful exercise to gain awareness about the behaviour of a GPR system, its accuracy and limits, and how to best utilize it

Land use change impacts on air quality and climate.

Historical land use and land cover change (referred to herein as “land use change”) has dramatically altered the Earth’s landscape, perturbing energy, moisture, and chemical fluxes and impacting the Earth’s climate. Land use change (LUC) in the next century has been projected to have profound impacts on regional climate. These changes connect to critical issues of food security, energy supply, and biodiversity. Large-scale perturbation of the biosphere will also play a major role in determining atmospheric composition, with implications for both air quality and climate. Our goal here is to review current understanding of the interplay between land use change and atmospheric chemistry, with a focus on short-lived atmospheric pollutants.National Science Foundation (U.S.) (Grant AGS-1238109)Natural Environment Research Council (Great Britain) (Grant NE/G015015/1