Technological developments as an answer to bridge management challenges

IABSE Symposium 2019, Towards a Resilient Built Environment - Risk and Asset Management, GUIMARAES, PORTUGAL, 27-/03/2019 - 29/03/2019Bridge management is a challenge as owners have to deal with limited financial resources to maintain the functionalities and safety of ageing structures. Demands on transportation networks change, due to regulatory developments, society's evolution and shifts with high expectations on the operational performance of roadway bridges with reduced congestion, delay, and accidents. To minimize intrusion in the transport flow, inspection and monitoring methods should be non?destructive, minimally invasive. They should be capable of yielding rapid and accurate inspection results allowing an adequate response from the asset manager. Research aims at including autonomously operating equipment (e.g. robotics), non?intrusive (remote or proximity) observation techniques, or other methods that ensure quality and performance control of the roadway bridges in time, more safely, more quickly and/or to a higher degree of accuracy and precision.The innovation subgroup in COST action TU1406 investigates novel condition monitoring and sensing technologies for the assessment of structural serviceability and safety. Advanced, integrated, cost-effective and reliable instrumentation solutions, techniques and concepts are looked at with the aim to provide data, that will be used to compute innovative performance indicators. In this context, this paper briefly reminds some significant challenges associated with bridge management and presents three examples of innovation in bridge monitoring and NDT investigation techniques

Sintering of lixiviated nano glass-ceramics: An original route to elaborate transparent ceramics

International audienceWe report the elaboration of translucent ZnGa2O4 ceramics by an innovative process, the sintering by Spark Plasma Sintering (SPS) of spinel ceramic powder obtained by the lixiviation of glass-ceramics. Indeed, a selective dissolution of the silica-rich glass matrix allows isolating ZnGa2O4 nanocrystals embedded in the silicate glass ceramic. This glass-ceramic is elaborated from the parent glass of composition 55 SiO2 5 Na2O 17 ZnO 23 Ga2O3 (%mol) that undergoes a subsequent heat-treatment at 1100 degrees C under air leading to the crystallization of zinc gallate spinel nanocrystals with size in the 20-60 nm range. Lixiviated nanocrystals are collected and sintered by SPS to get a bulk ceramic. While the transmittance of this ceramic is only 60% at 4.5 mu m, which is lower than the theoretical transmittance (82.5%), these first results are still promising and pave the way to new transparent ceramic processing route. Indeed, glass crystallization combined with selective lixiviation process is a powerful, non-conventional elaboration process that can further allow the stabilization and isolation of metastable crystalline phases with interesting functional properties

New KNbTeO6 transparent tellurate ceramics

International audienceNew transparent defect pyrochlore KNbTeO 6 ceramics were successfully prepared by Spark Plasma Sintering (SPS) of same composition polycrystalline powders elaborated by classic solid-state reaction from oxide precursors (K 2 CO 3 , Nb 2 O 5 , TeO 2) and followed by high energy milling powders. As such precursors are not available as commercial nanopowders, a suitable process has been developed by combining solid-state reactions and high energy milling. The determination of appropriate consolidation conditions and sintering parameters of the green body such prepared, are described in this paper. The resulting ceramic is transparent in both the visible and near infrared range (up to 5.5 μm). The maximum of transmittance is reached in the near infrared region around 2500 nm with a value of 78 % (1 mm thick sample), close to the maximum theoretical value of transmittance. This transparent KNbTeO 6 ceramic demonstrates a homogeneous and dense microstructure with an average grain size less than 500 nm. A small content of secondary phase has been detected by nanoscale observations without drastic effects on transparency. This ceramic exhibits very good mechanical properties similar to the Y 2 O 3 transparent ceramic, as well as interesting dielectric properties in the microwave range. This innovative method should drive the development of new transparent materials with technologically relevant applications