TY - CONF A1 - Niederleithinger, Ernst T1 - Advances in ultrasonic testing and monitoring of concrete structures N2 - Recent years have seen extended use of ultrasonic techniques for concrete infrastructure assessement. They are applied for quality assurance and condition assessement at bridges, power plants, dams and other important objects. However, there are still a couple of significant limitations. They include, but are not limited to depth of penetration, imaging complex structures or early stage detections of distributed damage. The talk will give information on recent research in this area. Specifically, the application of the unique deep penetration system LAUS is shown. Ultrasonic monitoring using embedded transducers to check for subtle and sudden changes in the material is introduced as well. Comments on initiatives for validation, standardization and certification will be given. T2 - 341e Conférence CERES CY - Online meeting DA - 26.10.2020 KW - Concrete KW - Ultrasound KW - Imaging KW - Monitoring PY - 2020 AN - OPUS4-51463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Abraham, Odile A1 - Larose, Eric T1 - A review on ultrasonic monitoring of concrete: coda wave interferometry and beyond N2 - The propagation of ultrasonic waves in concrete is affected by its micro- and macro-structure, geometry and properties as well as external influences as stress, temperature or moisture. In addition, age and degradation have a strong influence. Therefore, Ultrasound has been used to monitor concrete samples and structures since decades. However, early applications using conventional techniques as time-of flight or changes in amplitudes have been limited to detect changes in a late stage close to serviceability or ultimate load states. Around 2000, several new, more sensitive techniques adopted from geophysics or other field of material sciences have been introduced to research in ultrasonic monitoring of concrete. The most discussed methodologies are coda wave interferometry, a technique which allows to detect very subtle changes from repeated ultrasonic measurements. Nonlinear acoustic techniques help to identify e. g. cracks even in an inhomogeneous background. Both techniques can be combined. This paper reviews methods and results achieved so far on the laboratory scale and with full scale models the directions for future research and application is given as well. T2 - QNDE 2019 CY - Portland, OR, USA DA - 14.07.2019 KW - Ultrasound KW - Coda wave interferometry KW - Concrete KW - Nonlinear KW - Monitoring PY - 2019 SP - Paper 1234 AN - OPUS4-48686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prabhakara, Prathik T1 - Simulation and construction of a focussing borehole probe for ultrasonic investigations at sealing structures for radioactive waste repositories N2 - A novel ultrasonic borehole probe is developed for the quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The aim is to analyse the sealing structures made of salt concrete concerning potential cracks, delamination, and embedded objects. A first prototype of the probe uses 12 individual dry point contact (DPC) shear horizontal wave transducers separated by equidistant transmitter/receiver arrays, each consisting of six individual transducers. It is operated with a commercial handheld ultrasonic testing device used in civil engineering. In order to increase the generated sound pressure of the borehole probe, the number of transducers will be increased to 32 for the novel probe. In addition, a time-controlled excitation of the individual probes is used to steer a focused sound beam to a certain angle and focus on a certain distance based on calculated time delays. Hence, the sensitive test volume is more limited, and the signal-to-noise ratio of the received signals improved. This paper presents the validation of the newly developed phased array borehole probe by beam simulation and experimentally on a half-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction method, an optimised radiation characteristic of the probe, an improved signal quality and thus an increased reliability of the results in imaging is expected. This is of great importance to construct safe sealing structures needed for radioactive or toxic waste disposal. T2 - NDT UT-Online 21 CY - Online meeting DA - 01.11.2021 KW - Borehole probe KW - Engineered Barrier System (EBS) KW - SealWasteSafe KW - Phased array technique KW - Monitoring PY - 2021 AN - OPUS4-54500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - Das Themenfeldprojekt SealWasteSafe im Überblick N2 - Das Projekt SealWasteSafe verbessert Werkstofftechnik, Prüfverfahren und Überwachungsmethoden für sichere Verschlussbauwerke in Endlagern. Dieser Überblick fasst die laufenden Arbeiten in folgenden Bereichen zusammen: 1) Materialentwicklung und Dauerhaftigkeit; 2) Überwachung; 3) Inspektion. T2 - Online-Workshop „Dauerhafte Verschlussbauwerke für Endlager“ CY - Online meeting DA - 14.02.2022 KW - SealWasteSafe KW - Salzbeton KW - Verschlussbauwerke KW - Monitoring KW - Inspektion KW - Ultraschall PY - 2022 AN - OPUS4-55089 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epple, Niklas T1 - Ultrasonic monitoring of large-scale structures – input to engineering assessment N2 - Ultrasonic coda wave interferometry can detect small changes in scattering materials like concrete. We embedded ultrasonic transducers in the Gänstorbrücke Ulm, a monitored road bridge in Germany, to test the methodology. Since fall 2020, we've been monitoring parts of the bridge and comparing the results to commercial monitoring systems. We calculate signal and volumetric velocity changes using coda waves, and long-term measurements show that the influence of temperature on strains and ultrasound velocity changes can be monitored. Velocity change maps indicate that different parts of the bridge react differently to environmental temperature changes, revealing local material property differences. A load experiment with trucks allows calibration to improve detectability of possibly damaging events. Our work focuses on measurement reliability, potential use of and distinction from temperature effects, combination with complementary sensing systems, and converting measured values to information for damage and life cycle assessment. T2 - IALCCE 2023 CY - Milano, Italy DA - 02.07.2023 KW - Ultrasonic KW - Monitoring KW - Bridges KW - NDT KW - Coda PY - 2023 AN - OPUS4-58046 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epple, Niklas A1 - Sanchez Trujillo, Camila Andrea A1 - Niederleitinger, Ernst T1 - Ultrasonic monitoring of large-scale structures – input to engineering assessment N2 - Ultrasonic coda wave interferometry can detect small changes in scattering materials like concrete. We embedded ultrasonic transducers in the Gänstorbrücke Ulm, a monitored road bridge in Germany, to test the methodology. Since fall 2020, we've been monitoring parts of the bridge and comparing the results to commercial monitoring systems. We calculate signal and volumetric velocity changes using coda waves, and long-term measurements show that the influence of temperature on strains and ultrasound velocity changes can be monitored. Velocity change maps indicate that different parts of the bridge react differently to environmental temperature changes, revealing local material property differences. A load experiment with trucks allows calibration to improve detectability of possibly damaging events. Our work focuses on measurement reliability, potential use of and distinction from temperature effects, combination with complementary sensing systems, and converting measured values to information for damage and life cycle assessment. T2 - IALCCE 2023 CY - Milano, Italy DA - 02.07.2023 KW - Ultrasonic KW - Monitoring KW - Bridge KW - NDT KW - coda PY - 2023 SP - 1 EP - 8 PB - IALCCE CY - Milan AN - OPUS4-58047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - PREDIS The pre-disposal management of radioactive waste N2 - This presentation summarizes the opbjectives and the progress of the EURATOM project PREDIS (pre-disposal management of radioactive waste) and its workpackage 7 in particular. Focus is on the development of wireless sensors for monitoring radioactive waste packages, measuring radiation, temperature, pressure and humidity. T2 - DigiDecom 2022 CY - Halden, Norway DA - 18.10.2022 KW - Radioactive waste KW - Monitoring KW - Wireless KW - RFID PY - 2022 AN - OPUS4-56321 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schönsee, Eric A1 - Hüsken, Götz A1 - Jeyifous, Olubunmi Anthony A1 - Mezhov, Alexander A1 - Strangfeld, Christoph T1 - Calculating rheological properties of fresh mortar for additive manufacturing based on experimental, multi-sensor data N2 - Additive manufacturing of concrete structures is a novel and emerging technology. Freecontouring in civil engineering, which allows for entirely new designs, is a significant advantage. Inthe future, lower construction costs are expected with increased construction speeds and decreasingrequired materials and workers. However, architects and civil engineers rely on a certain quality ofexecution to fulfil construction standards. Although several techniques and approaches demonstratethe advantages, quality control during printing is highly challenging and rarely applied. Due to thecontinuous mixing process commonly used in 3D concrete printing, it is impossible to exclude varia-tions in the dry mixture or water content, and a test sample cannot be taken as a representative samplefor the whole structure. Although mortar properties vary only locally, a defect in one layer duringprinting could affect the entire integrity of the whole structure . Therefore, real-time process monitor-ing is required to record and document the printing process.At the Bundesanstalt für Materialforschung und -prüfung (BAM) a new test rig for the additive man-ufacturing of concrete is built. The primary purpose is measuring and monitoring the properties of amortar during the printing process.The following study investigates an approach for calculating yield stress and plastic viscosity based onexperimentally recorded pressure data. The calculations assume that fresh mortar behaves as a Bing-ham fluid and that the Buckingham-Reiner-equation is applicable. A test setup consisting of rigid pipeswith integrated pressure sensors at different positions is utilized.Monitoring the printing process with different sensors is crucial for the quality control of an ongoingprocess. T2 - Non-Traditional Cement and Concrete 2023 Conference CY - Brno, Czech Republic DA - 25.06.2023 KW - 3DCP KW - Monitoring KW - Additive manufacturing KW - Rheology KW - Bingham fluid KW - Concrete printing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598179 DO - https://doi.org/10.4028/p-EV4gPv SN - 1662-0356 VL - 145 SP - 131 EP - 139 PB - Trans Tech Publications CY - Baech AN - OPUS4-59817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hüsken, Götz A1 - Jeyifous, Olubunmi Anthony A1 - Schönsee, Eric A1 - Strangfeld, Christoph T1 - An assessment of the repeatability of 3D printed concrete structures N2 - Additive manufacturing of concrete structures, also known as 3D concrete printing, is a technology that received a lot of attention over the past decade due to its financial an ecological advantage as sustainable construction technology. Although several techniques and approaches demonstrate these advantages, quality control during printing is highly challenging and rarely applied and harmonized standards are not existing. Due to the continuous mixing process used in 3D concrete printing, it is impossible to exclude variations in the dry mixture or water content, and a single test sample is insufficient to be representative for the whole structure. A defect in one layer during the printing can affect the entire integrity of the whole structure. This study shows the results of an arch designed as framework structure that was printed multiple times under the same boundary conditions using an extrusion-based 3D concrete printer. Each arch was tested for its mechanical strength and load bearing behavior. The results of the mechanical testing of the printed arches are compared with material data obtained by classical tests and discussed regarding their statistical significance. T2 - Digital Concrete 2024 CY - Munich, Germany DA - 04.09.2024 KW - 3D concrete printing KW - Repeatability KW - Monitoring KW - Process control KW - Quality control PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611012 DO - https://doi.org/10.24355/dbbs.084-202408150641-0 SP - 1 EP - 9 PB - TU Braunschweig AN - OPUS4-61101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönsee, Eric T1 - Investigations on multi-sensor data for monitoring volume flow N2 - Extrusion based 3D concrete printing (3DCP) is a growing technology because of its high potential for automating construction and the new possibilities of de-sign. In conventional construction methods, a sample is taken to be representative for one material batch. However, in 3DCP continuous mixing is used which re-sults in variations during the mixing process. Therefore, one sample is not repre-sentative for the entire structure. This leads to the necessity of continuous and re-al-time process monitoring. At the Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, a test rig is developed to allow for comprehensive monitoring of the printing process. For this purpose, sensors for torque, temperature, pressure and moisture are in-stalled into the pipe. A laser scanner is installed at the nozzle to acquire infor-mation about the geometry of the extruded material. This study focuses on the variations of pressure and temperature which are caused by changes in the material due to the ongoing mixing process. Preliminary results indicate that changes in the material properties cause changes in the sensor signals as well. These changes can be observed in various sensors with a delay, caused by material which is carried downstream. In the following, the data is ana-lysed to investigate if the changing material and the so caused change in pressure can be used to calculate volume flow. T2 - Digital Concrete 2024 CY - Munic, Germany DA - 04.09.2024 KW - 3D concrete printing KW - Monitoring KW - Pressure PY - 2024 AN - OPUS4-60997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Ultraschall-Messsystem für die Langzeitüberwachung von Betonkonstruktionen N2 - Ultraschallmessverfahren werden seit Langem erfolgreich für Prüfaufgaben im Bauwesen eingesetzt. Die dauerhafte Überwachung und frühzeitige Erkennung von Schäden an komplexen Neubauten und alternder Infrastruktur kann mittels Ultraschall-Transmissionsmessungen und speziellen Auswertemethoden, wie z. B. Korrelationverfahren und Codawelleninterferometrie, realisiert werden. Für die Dauerüberwachung wurde ein kompaktes System entwickelt, das Ultraschall-Messdaten erfassen und ins Internet auf einen FTP-Server übertragen kann. Es können hierbei alle angeschlossenen Prüfköpfe für jede Messung wahlweise als Sender oder Empfänger geschaltet werden. Es wurden Vorverstärker entwickelt, bei denen die Versorgung mit Strom über die Messleitung erfolgt. Dadurch können die Verstärker nahe am Prüfkopf positioniert werden. Durch Änderungen in den Ultraschall-Signalen können Schädigungen des Bauteils, wie z.B. Risse, in Echtzeit erkannt werden. T2 - DGZfP DACH-Jahrestagung CY - Friedrichshafen, Germany DA - 27.05.2019 KW - Ultraschall KW - Monitoring KW - Codawelleninterferometrie KW - Eingebettete Sensorik PY - 2019 AN - OPUS4-48144 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Baensch, Franziska A1 - Johann, Sergej A1 - Sturm, Patrick A1 - Mielentz, Frank A1 - Prabhakara, Prathik A1 - Hofmann, Detlef A1 - Niederleithinger, Ernst A1 - Kühne, Hans-Carsten T1 - SealWasteSafe: materials technology, monitoring techniques, and quality assurance for safe sealing structures in underground repositories N2 - Within the project SealWasteSafe, we advance construction materials and monitoring concepts of sealing structures applied for underground disposal of nuclear or toxic waste. As these engineered barriers have high demands concerning integrity, an innovative alkali-activated material (AAM) is improved and tested on various laboratory scales. This AAM has low reaction kinetics related to a preferential slow release of the heat of reaction in comparison to alternative salt concretes based on Portland cement or magnesium oxychloride cements. Hence, crack formation due to thermally induced strain is reduced. After successful laboratory scale analysis (Sturm et al., 2021), the AAM is characterised on a larger scale by manufacturing test specimens (100–300 L). Conventional salt concrete (DBE, 2004) and the newly developed AAM are compared using two specimen geometries, i.e. cylindrical and cuboid. A comprehensive multisensor monitoring scheme is developed to compare the setting process of AAM and salt concrete for these manufactured specimens. The analysed parameters include temperature and humidity of the material, acoustic emissions, and strain variations. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete, enable wireless access to temperature and humidity measurements and are compared to conventional cabled systems. Additionally, fibre-optic sensors (FOS) are embedded to record strain, but also have potential to record temperature and moisture conditions. Part of this project aims at demonstrating the high reliability of sensors and also their resistance to highly alkaline environments and to water intrusion along cables or at sensor locations. Further technical improvements were implemented so that first results clearly show the scalability of the setting process from previous small-scale AAM experiments and particularly the high potential of the newly developed approaches. Furthermore, ultrasonic methods are used for quality assurance to detect obstacles, potential cracks and delamination. On the one hand, both active and passive ultrasonic measurements complement the results obtained from the multisensor monitoring scheme for the produced specimens. On the other hand, the unique large aperture ultrasonic system (LAUS) provides great depth penetration (up to nearly 10 m) and can thus be applied at in situ sealing structures built as a test site in Morsleben by the Federal Company for Radioactive Waste Disposal (Bundesgesellschaft für Endlagerung, BGE) as shown by Effner et al. (2021). An optimised field lay-out identified from forward modelling studies and advanced imaging techniques applied to the measured data will further improve the obtained results. To characterise the inside of the test engineered barrier and achieve a proof-of-concept, an ultrasonic borehole probe is developed to enable phased arrays that can further improve the detection of potential cracks. Modelling results and first analysis of semispherical specimens confirmed the reliability of the directional response caused by the phased arrays of the newly constructed ultrasonic borehole probe. Overall, the project SealWasteSafe improves the construction material, multisensor monitoring concepts and ultrasonics for quality assurance. This will help to develop safe sealing structures for nuclear waste disposal. The outcomes are particularly valuable for salt as a host rock but partly also transferrable to alternative conditions. T2 - Safe ND Interdisciplinary research symposium on the safety of nuclear disposal practices CY - Berlin, Germany DA - 10.11.2021 KW - Borehole probe KW - SealWasteSafe KW - Engineered barrier KW - Materials technology KW - Monitoring KW - AAM KW - Ultrasound PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539172 DO - https://doi.org/10.5194/sand-1-127-2021 VL - 1 SP - 127 EP - 128 PB - Copernicus AN - OPUS4-53917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Xin A1 - Niederleithinger, Ernst A1 - Hindersmann, Iris T1 - The installation of embedded ultrasonic transducers inside a bridge to monitor temperature and load influence using coda wave interferometry technique N2 - This article presents a unique method of installing a special type of embedded ultrasonic transducers inside a 36-m-long section of an old bridge in Germany. A small-scale load test was carried out by a 16 ton truck to study the temperature and load influence on the bridge, as well as the performance of the embedded transducers. Ultrasonic coda wave interferometry technique, which has high sensitivity in detecting subtle changes in a heterogeneous medium, was used for the data evaluation and interpretation. The separation of two main influence factors (load effect and temperature variation) is studied, and future applications of wave velocity variation rate Φ for structural health condition estimation are discussed. As a preliminary research stage, the installation method and the performance of the ultrasonic transducer are recognized. Load- and temperature-induced weak wave velocity variations are successfully detected with a high resolution of 10−4%. The feasibility of the whole system for long-term structural health monitoring is considered, and further research is planned. KW - Ultrasound KW - Bridge KW - Monitoring KW - coda wave interferometry KW - embedded PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527978 DO - https://doi.org/10.1177/14759217211014430 SN - 1475-9217 VL - 21 IS - 3 SP - 913 EP - 927 PB - SAGE AN - OPUS4-52797 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, T. A1 - Niederleithinger, Ernst T1 - Combining Passive and Active Ultrasonic Stress Wave Monitoring Techniques: Opportunities for Condition Evaluation of Concrete Structures N2 - Concrete structures are invaluable assets to a society and managing them efficiently and effectively can be supported by information gathered through structural health monitoring (SHM). In this paper, a combined approach based on passive, i.e., acoustic emission (AE), and active, i.e., ultrasonic stress wave (USW) monitoring techniques for application to concrete structures is proposed and evaluated. While AE and USW are based on the same underlying physics, i.e., wave motion in solids, they differ fundamentally with respect to the nature of the source. For the former, external stimuli such as mechanical loads or temperature cause the rapid release of energy from initially unknown locations. As a result, AE events are unique and cannot be repeated. For the latter, a known source at a known location is employed at a specified time. This approach is thus controlled and repeatable. It is argued that a combination of these two techniques has the potential to provide a more comprehensive picture of ongoing fracture processes, damage progression, as well as slowly occurring aging and degradation mechanisms. This combined approach does thus promise new opportunities to support condition assessment of concrete structures. After providing an overview and comparison of the two techniques, results, and observations from a full-scale laboratory experiment and an in-service bridge monitoring study are discussed to demonstrate the promise of the proposed combined monitoring approach. Finally, suggestions for further work are presented. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Ultrasound KW - Acoustic emission KW - Concrete structures KW - Monitoring PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563242 UR - https://www.ndt.net/article/ndtce2022/paper/61607_manuscript.pdf SP - 1 EP - 11 PB - NDT.net AN - OPUS4-56324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holt, E. A1 - Oksa, M. A1 - Nieminen, M. A1 - Abdelouas, A. A1 - Banford, A. A1 - Fournier, M. A1 - Mennecart, T. A1 - Niederleithinger, Ernst T1 - Predisposal conditioning, treatment, and performance assessment of radioactive waste streams N2 - Before the final disposal of radioactive wastes, various processes can be implemented to optimise the waste form. This can include different chemical and physical treatments, such as thermal treatment for waste reduction, waste conditioning for homogenisation and waste immobilisation for stabilisation prior to packaging and interim storage. Ensuring the durability and safety of the waste matrices and packages through performance and condition assessment is important for waste owners, waste management organisations, regulators and wider stakeholder communities. Technical achievements and lessons learned from the THERAMIN and PREDIS projects focused on low- and intermediate-level waste handling is shared here. The recently completed project on Thermal Treatment for Radioactive Waste Minimization and Hazard Reduction (THERAMIN) made advances in demonstrating the feasibility of different thermal treatment techniques to reduce volume and immobilise different streams of radioactive waste (LILW) prior to disposal. The Pre-Disposal Management of Radioactive Waste (PREDIS) project addresses innovations in the treatment of metallic materials, liquid organic waste and solid organic waste, which can result from nuclear power plant operation, decommissioning and other industrial processes. The project also addresses digitalisation solutions for improved safety and efficiency in handling and assessing cemented-waste packages in extended interim surface storage. KW - Radioactive waste KW - Predisposal KW - Treatment KW - Monitoring PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-567276 DO - https://doi.org/10.1051/epjn/2022036 SN - 2491-9292 VL - 8 SP - 1 EP - 6 PB - EDP Sciences CY - Les Ulis AN - OPUS4-56727 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prabhakara, Prathik A1 - Mielentz, Frank A1 - Stolpe, Heiko A1 - Behrens, Matthias A1 - Lay, Vera A1 - Niederleithinger, Ernst T1 - Construction and validation of a novel phased array borehole probe for ultrasonic investigations at sealing structures in radioactive repositories N2 - A new type of ultrasonic borehole probe is currently under development for the quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The goal is to examine the sealing structures made of salt concrete for possible cracks, delamination, and embedded objects. Earlier prototype probes use 12 or 16 individual dry point contact (DPC) horizontal shear wave transducers grouped into a transmitter and a receiver array, each made up of six or eight individual transducers. They are operated with a commercially available portable ultrasonic flaw detector used in the civil engineering industry. To increase the generated sound pressure of the borehole probe, the number of transducers in the novel probe is increased to 32. In addition, timed excitation of each probe is used to direct a focused sound beam to a specific angle and distance based on calculated time delays. Hence, the sensitive test volume is limited, and the signal-to-noise ratio of the received signals is improved. This paper presents the validation of the newly developed phased array borehole probe by beam computation in CIVA software and experimental investigations on a semi-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction techniques, an optimised radiation pattern of the probe is expected to improve the signal quality and thus increase the reliability of the imaging results. This is of great importance for the construction of safe sealing structures needed for the disposal of radioactive or toxic waste. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Borehole probe KW - Phased array technique KW - SealWasteSafe KW - Monitoring KW - Engineered barrier; PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568016 SN - 1435-4934 SP - 1 EP - 4 PB - NDT.net AN - OPUS4-56801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holt, Erika A1 - Oksa, Maria A1 - Banford, Anthony A1 - Carbol, Paul A1 - Abdelouas, Abdesselam A1 - Giboire, Isabelle A1 - Mennecart, Thierry A1 - Niederleithinger, Ernst T1 - Predisposal Radioactive Waste Management (PREDIS) Project Final Achievements and Impacts Overview N2 - The PREDIS project on Predisposal of Radioactive Waste has succeeded in developing and implementing new methods, processes and technologies for treatment of challenging low-level waste (LLW) and intermediate level waste (ILW) streams. Over the 4-year duration, this Euratom project of 47 partners from 17 Member States has worked in close collaboration with 25 End User industrial members to advance the technologies associated with predisposal issues. This has included characterisation followed by treatment, conditioning and processing of metallics, liquid organic and solid organic wastes as well as with digitalization technologies for assessing performance of concrete waste packages and pre-disposal storage. Long-term modelling and performance testing have been done to verify the safety and effectiveness of the new or enhanced solutions. Value Assessments were done for some of the new solutions to ensure implementors would have sufficient tools for making choices about the potential implementation. This included life-cycle assessment of quantitative sustainability indicators and life cycle-costing for economic indicators. This project addressed new guidance on Waste Acceptance Criteria and contributed with a revised Strategic Research Agenda to guide future predisposal activities, complimentary to the holistic waste management programme. Knowledge Management actions were also an integral part of the whole project to foster competence development and capturing knowledge. Actions included training, mobility, and guidance especially through online forums such as webinars and digital training. This paper provides a snapshot of some of the key outcomes and impacts from the project, from technical as well as strategic and knowledge perspectives. KW - Nuclear waste KW - Pre-disposal KW - Intermediate storage KW - Treatment KW - Monitoring PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638480 DO - https://doi.org/10.1051/epjn/2025028 SN - 2491-9292 VL - 11 SP - 1 EP - 7 PB - EDP Sciences AN - OPUS4-63848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Mielentz, Frank A1 - Prabhakara, Prathik A1 - Baensch, Franziska A1 - Johann, Sergej A1 - Hofmann, Detlef A1 - Sturm, Patrick A1 - Stamm, Michael A1 - Niederleithinger, Ernst T1 - Multi-sensory monitoring and ultrasound for quality assurance at underground sealing structures N2 - Within the safety concepts of underground disposal sites of nuclear waste, engineered barriers play an important role. As these sealing structures have high demands concerning integrity, we aim at advancing the available construction materials, monitoring, and inspection techniques within the project SealWasteSafe. A specifically developed alkali-activated material is compared to classical salt concrete. A comprehensive multi-sensory monitoring scheme is used at 150-340 l specimens to monitor setting and hardening of both materials. All sensors are demonstrated to resist the highly alkaline environments. Besides cabled and wireless temperature and humidity of the materials, strain variations using fibre optic sensors and acoustic emissions are recorded over periods of at least 28 days, partly for more than eight months. After hardening of the specimens, further nondestructive evaluations using ultrasonic echo and thermographic measurements are conducted. Preliminary results proof the suitability of the tested sensors and clearly highlight differences between the tested materials. Particularly, the newly developed alkali-activated material shows lower acoustic emission activity indicating less cracking activity. Additionally, unique ultrasonic methods will enable better images of potential internal objects and cracks at in-situ sealing structures. A largescale ultrasonic system is optimised to reliably detect objects at a depth exceeding 9 m while still obtaining a good resolution. Modelling studies show the potential of further increasing the distance between individual transducer arrays. Additionally, a new ultrasonic borehole probe using phased arrays allowing for beam focussing is constructed and tested. Laboratory measurements at a halfcylindrical concrete specimen coincide well with the previous modelling. In total, the presented safe materials, detailed monitoring approaches and ultrasonic quality assurance methods will help to obtain safe sealing structures within salt as a host rock. The concepts can partly be transferred to sealing structures in alternative host rocks and will also be valuable for non-nuclear waste repositories. T2 - NDE NucCon CY - Espoo, Finland DA - 25.01.2023 KW - SealWasteSafe KW - Engineered barriers KW - Monitoring KW - Embedded sensors KW - Ultrasonic imaging PY - 2023 SP - 2 EP - 10 AN - OPUS4-56928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Niederleithinger, Ernst A1 - Köpp, Christan T1 - Monitoring and digital tools for pre-disposal handling of cemented wastes N2 - Multifaceted developments for pre-disposal management of low and intermediate level radioactive waste are undertaken in the EC funded project PREDIS. In work package 7, innovations in cemented waste handling and pre-disposal storage are advanced by testing and evaluating. To provide better means for safe and effective monitoring of cemented waste packages including prediction tools to assess the future integrity development during pre-disposal activities, several monitoring and digital tools are evaluated and improved. Both safety enhancement (e. g. less exposure of testing personnel) and cost effectiveness are part of the intended impact. Current methods to pack, store, and monitor cemented wastes are identified, analysed and improved. Innovative integrity testing and monitoring techniques applied to evaluate and demonstrate package and storage quality assurance are further developed. The work includes but is not limited to inspection methods such as muon imaging, wireless sensors integrated into waste packages as well as external package and facility monitoring such as remote fiber optical sensors. The sensors applied will go beyond radiation monitoring and include proxy parameters important for long term integrity assessment (e. g. internal pressure). The measured data will be used in digital twins of the packages for specific simulations (geochemical, integrity) providing a prediction of future behaviour. Machine Learning techniques trained by the characterization of older packages will help to connect the models to the actual data. As data handling, processing and fusion are crucial for both the monitoring and the digital twin model, all data (measured and simulated) will be collected in a joint data base and connected to a decision framework. Finally, the implementation of the improved techniques will be tested at actual facilities. An overview about various relevant tools, their interconnections, and first research results will be shown. T2 - 9th IGD-TP Symposium CY - Zurich, Switzerland DA - 20.09.2022 KW - Predis KW - Monitoring KW - Sensors KW - Simulation KW - Digital twin PY - 2022 AN - OPUS4-55827 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schönsee, Eric T1 - Calculating rheological properties of fresh mortar for additive manufacturing based on experimental, multi sensor data N2 - Additive manufacturing of concrete structures is a novel and emerging technology. Free contouring in civil engineering, which allows for entirely new designs, is a significant advantage. In the future, lower construction costs are expected with increased construction speeds and decreasing required materials and workers. However, architects and civil engineers rely on a certain quality of execution to fulfil construction standards. Although several techniques and approaches demonstrate the advantages, quality control during printing is highly challenging and rarely applied. Due to the continuous mixing process commonly used in 3D concrete printing, it is impossible to exclude variations in the dry mixture or water content, and a test sample cannot be taken as a representative sample for the whole structure. Although mortar properties vary only locally, a defect in one layer during printing could affect the entire integrity of the whole structure . Therefore, real-time process monitoring is required to record and document the printing process. At the Bundesanstalt für Materialforschung und -prüfung (BAM) a new test rig for the additive manufacturing of concrete is built. The primary purpose is measuring and monitoring the properties of a mortar during the printing process. The following study investigates an approach for calculating yield stress and plastic viscosity based on experimentally recorded pressure data. The calculations assume that fresh mortar behaves as a Bingham fluid and that the Buckingham-Reiner-equation is applicable. A test setup consisting of rigid pipes with integrated pressure sensors at different positions is utilized. Monitoring the printing process with different sensors is crucial for the quality control of an ongoing process. T2 - Non-Tradijtional Cement and Concrete CY - Brno, Czech Republic DA - 25.06.2023 KW - 3DCP KW - Monitoring KW - Additive Manufacturing KW - Rheology KW - Bingham Fluid PY - 2023 AN - OPUS4-58144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - PREDIS: Innovative ways for pre disposal treatment and monitoring of low and medium radioactive waste N2 - The EURATOM PREDIS project (http://www.predis-h2020.eu, last access:TS1) targets the development and implementation of activities for predisposal treatment of radioactive waste streams other than nuclear fuel and high-level radioactive waste. It started on 1 September 2020 with a 4 year duration. The consortium includes 47 partners from 17 member states. The overall budget of the project is EUR23.7 million, with EC contribution of EUR 14 million. The PREDIS project develops and increases the technological readiness level (TRL) of treatment and conditioning methodologies for wastes for which no adequate or industrially mature Solutions are currently available, including metallic materials, liquid organic waste and solid organic waste. The PREDIS project also develops innovations in cemented waste handling and predisposal storage by testing and evaluating. The technical work packages align with priorities formulated within the Roadmap Theme 2 of EURAD (https://www.ejp-eurad.eu/TS2), Nugenia Global Vision (https://snetp.eu/nugenia/TS3) and with those identified by the project’s industrial end users group (EUG). The PREDIS will produce tools guiding decision making on the added value of the developed technologies and their impact on the design, safety and economics of waste management and disposal. Four technical work packages are focusing on specific waste types: metallic, liquid organic, solid organic, and cemented wastes. For the first three, the main aim lies in processing, stabilizing, and packaging the different waste streams, e.g. by using novel geopolymers, to deliver items which are in line with national and international waste acceptance criteria. In contrast, the fourth technical work package has a different focus. To provide better ways for a safe and effective monitoring of cemented waste packages including prediction tools to assess the future integrity development during predisposal activities, several digital tools are evaluated and improved. Safety enhancement (e.g. less exposure of testing personnel) and cost-effectiveness are part of the intended impact. The work includes but is not limited to inspection methods, such as muon imaging, wireless sensors integrated into waste packages as well as external package and facility monitoring, such as remote Fiber optic sensors. The sensors applied will go beyond radiation monitoring and include proxy parameters important for long-term integrity assessment (e.g. internal pressure). Sensors will also be made cost-effective to allow the installation of many more sensors compared to current practice. The measured data will be used in digital Twins of the waste packages for specific simulations (geochemical, integrity) providing a prediction of future behavior. Machine learning techniques trained by the characterization of older waste packages will help to connect the models to the current data. All data (measured and simulated) will be collected in a joint database and connected to a decision framework to be used at actual facilities. The presentation includes detailed information about the various tools under consideration in the Monitoring of cemented waste packages, their connection and first results of the research. T2 - Safety of Nuclear Waste Disposal CY - Berlin, Germany DA - 10.11.2021 KW - Radioactive waste disposal KW - RFID KW - Monitoring KW - Cemented waste PY - 2021 AN - OPUS4-54157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultrasonic methods for concrete: To boldly see, what we have not seen before N2 - This keynote talk at NDE 2019 discusses specific progress in ultrasonic testing of concrete structures. A deep penetration instrument (LAUS) is introduced as well as advanced imaging methods adopted from geophysics and new approaches to ultrasonic monitoring. T2 - NDE 2019 CY - Bangalore, India DA - 05.12.2019 KW - NDT KW - Concrete KW - Ultrasound KW - Imaging KW - Monitoring PY - 2019 AN - OPUS4-50170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Epple, Niklas A1 - Fontoura Barroso, Daniel A1 - Clauß, F. A1 - Ahrens, M. A. A1 - Mark, P. ED - Krieger, J. ED - Isecke, B. T1 - Ultraschallbasierte Überwachung von Stahl- und Spannbeton-konstruktionen – erste Ergebnisse der DFG-Forschungsgruppe 2825 CoDA N2 - Die Überwachung von Bauteilen aus Stahl- oder Spannbeton mit Ultraschall hat in Labor- und Technikumsversuchen schon vielversprechende Ergebnisse gezeigt. Besonders gute Resultate wurden dabei mit eingebetteten Ultraschalltrans-ducern und bei Auswertung der Daten mit der hochsensiblen Codawelleninterferometrie erzielt. Erfasst werden können neben Temperatur- und Feuchteeffekten auch Belastungszustände und jegliche Art von Schädigung, die mit Mikro- oder Makrorissbildung einhergeht. Seit 2019 untersucht die DFG-Forschergruppe 2825 „CoDA“ (Sprecher: Prof. Christoph Gehlen, TU München) ver-schiedenste Aspekte dieser innovativen Technologie mit dem Ziel, Einflussgrößen quantitativ zu erfassen, Umweltein-flüsse zu korrigieren und 3D-Auswerteverfahren zu verbessern. Final soll eine am Bauwerk einsatzfähige Methode ent-stehen, die klassische Monitoringverfahren ergänzt und erweitert sowie Input zu einem Update des statischen Systems liefert. Aufgaben der BAM in der Forschergruppe ist neben Verbesserung und Adaptierung der Messsystem und Sensorik auch Langzeitversuche an einem Großobjekt und Testinstallationen an Realbauwerken. Hierzu liegen erste Ergebnisse vor, die zeigen, dass die Technologie auch außerhalb des Labors einsatzfähig ist. T2 - 4. Brückenkolloquium CY - Online meeting DA - 08.09.2020 KW - Brücke KW - Monitoring KW - Ultraschall KW - Codawelleninterferometrie PY - 2020 SN - 978-3-8169-3518-6 SP - 473 EP - 480 PB - expert CY - Tübingen AN - OPUS4-51205 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultraschallbasierte Überwachung von Stahl- und Spannbeton-konstruktionen – erste Ergebnisse der DFG-Forschungsgruppe 2825 CoDA N2 - Die Überwachung von Bauteilen aus Stahl- oder Spannbeton mit Ultraschall hat in Labor- und Technikumsversuchen schon vielversprechende Ergebnisse gezeigt. Besonders gute Resultate wurden dabei mit eingebetteten Ultraschalltrans-ducern und bei Auswertung der Daten mit der hochsensiblen Codawelleninterferometrie erzielt. Erfasst werden können neben Temperatur- und Feuchteeffekten auch Belastungszustände und jegliche Art von Schädigung, die mit Mikro- oder Makrorissbildung einhergeht. Seit 2019 untersucht die DFG-Forschergruppe 2825 „CoDA“ (Sprecher: Prof. Christoph Gehlen, TU München) ver-schiedenste Aspekte dieser innovativen Technologie mit dem Ziel, Einflussgrößen quantitativ zu erfassen, Umweltein-flüsse zu korrigieren und 3D-Auswerteverfahren zu verbessern. Final soll eine am Bauwerk einsatzfähige Methode ent-stehen, die klassische Monitoringverfahren ergänzt und erweitert sowie Input zu einem Update des statischen Systems liefert. Aufgaben der BAM in der Forschergruppe ist neben Verbesserung und Adaptierung der Messsystem und Sensorik auch Langzeitversuche an einem Großobjekt und Testinstallationen an Realbauwerken. Hierzu liegen erste Ergebnisse vor, die zeigen, dass die Technologie auch außerhalb des Labors einsatzfähig ist. T2 - 4. Brückenkolloquium CY - Online meeting DA - 08.09.2020 KW - Ultraschall KW - Monitoring KW - Brücke KW - Codawelleninterferometrie PY - 2020 AN - OPUS4-51206 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Oesch, Tyler T1 - Proposed Project SealWasteSafe: Materials Technology, Quality Assurance and Monitoring Techniques for Safe Sealing Systems in Underground Repositories N2 - The proposed BAM project SealWasteSafe will advance the state of the art for the construction and monitoring of safe sealing systems for underground repositories of radioactive or toxic waste. During this project, a novel salt concrete exhibiting neither significant cracking nor shrinkage will be optimized for use in the sealing systems. The composition of this material will be based on alkali-activated materials, which are characterized by particularly small thermal deformations during the hardening reaction. Quality assurance and continuous monitoring systems developed during this project will be demonstrated not only for high reliability, but also for resistance to highly alkaline environments and to water intrusion along cables or at sensor locations. A variety of sensors will be used in combination with wireless Radio Frequency Identification (RFID) technology to record moisture, temperature, and, if necessary, corrosion activity within the sealing system. Distributed Fibre Optic Sensor (FOS) technology will also be used for strain, temperature, and moisture content measurement. Ultrasound-based measuring methods will be utilized for the detection of cracks and delaminations. Additionally, digital image correlation and acoustic emission analysis will be used for deformation measurements and crack detection. A novel borehole probe and advanced ultrasound imaging techniques will be further developed to track cracks and delaminations within the host rock in 3D. The surface-based Large Aperture Ultrasound System (LAUS) will also be utilized to detect cracks and delaminations deep below the exterior surface of the sealing system. Although the focus of this project will be on the host rock salt, the resulting technologies will be intentionally developed in a way that facilitates their adaptation to other host rocks. T2 - 2nd International Conference on Monitoring in Geological Disposal of Radioactive Waste CY - Paris, France DA - 09.04.2019 KW - SealWasteSafe KW - Radioactive Waste Disposal KW - Underground Repositories KW - Alkali-Activated Material KW - Monitoring PY - 2019 AN - OPUS4-47776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, T. A1 - Murtuz, A. K. M. G. A1 - Hafiz, A. A1 - Dusicka, P. A1 - Niederleithinger, Ernst ED - Gabrijel, I. ED - Grosse, C. ED - Skazlić, M. T1 - Post-earthquake damage evaluation of concrete structures using ultrasonic monitoring: A proof-of concept laboratory study N2 - In earthquake-prone regions such as the Pacific Northwest, damage assessment tools are needed to enable safety evaluations to support recovery. Currently, damage assessment is performed primarily by visual inspection and is often impossible for structural members that are inaccessible, such as deep foundations or interior members hidden by cladding. This study explores the possibility of using embedded ultrasonic transducers to monitor reinforced concrete members for damage progression under earthquake loading. A novel methodology is proposed where changes in the member condition due to an increase in the earthquake-type loading of a full-scale column-foundation specimen are correlated with changes in the recorded ultrasonic waveforms. The discussed preliminary analysis of the ultrasonic signals is based on wave propagation velocity, changes in the coda wave portion, and maximum amplitude of the signals. Three embedded transducers were used to continuously monitor the laboratory specimen during destructive testing. This paper provides an overview of the proposed methodology, outlines the laboratory experiment, and discusses some preliminary observations. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.3.2019 KW - Concrete KW - Monitoring KW - Ultrasound KW - earthquake PY - 2019 SN - 978-2-35158-227-5 DO - https://doi.org/10.1007/978-3-031-07258-1_84 SP - 112 EP - 119 PB - RILEM Publications S.A.R.L. CY - Paris, France AN - OPUS4-47679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst ED - Gabrijel, Ivan ED - Grosse, Christian ED - Skazlić, Marijan T1 - Ultrasonic monitoring of structural concrete elements N2 - Ultrasonic transmission measurements are used to monitor concrete elements mostly on a laboratory scale since decades. Recently, coda wave interferometry, a technique adapted from seismology, has been introduced to civil engineering experiments. It can be used to reveal subtle changes in concrete samples and even large construction elements without having a transducer directly at the location where the change is taking place. The methodology works best with embedded transducers to avoid coupling issues or excessive environmental influence. These transducers can be used for newly built and existing structures. Recently, large concrete beams have been equipped with a network of transducers and loaded until failure. Using code wave interferometry, it was possible to visualize stress fields and damaged areas. This paper gives an overview of the state of the art, recent results achieved at BAM and a task list for further results and development. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.3.2019 KW - Concrete KW - Ultrasound KW - Monitoring KW - coda wave interferometry PY - 2019 SN - 978-2-35158-227-5 SP - 1 EP - 11 PB - RILEM Publications S.A.R.L. CY - Paris, France AN - OPUS4-47677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - A review on ultrasonic monitoring of concrete: coda wave interferometry and beyond N2 - The propagation of ultrasonic waves in concrete is affected by its micro- and macro-structure, geometry and properties as well as external influences as stress, temperature or moisture. In addition, age and degradation have a strong influence. Therefore, Ultrasound has been used to monitor concrete samples and structures since decades. However, early applications using conventional techniques as time-of flight or changes in amplitudes have been limited to detect changes in a late stage close to serviceability or ultimate load states. Around 2000, several new, more sensitive techniques adopted from geophysics or other field of material sciences have been introduced to research in ultrasonic monitoring of concrete. The most discussed methodologies are coda wave interferometry, a technique which allows to detect very subtle changes from repeated ultrasonic measurements. Nonlinear acoustic techniques help to identify e. g. cracks even in an inhomogeneous background. Both techniques can be combined. This paper reviews methods and results achieved so far on the laboratory scale and with full scale models the directions for future research and application is given as well. T2 - QNDE 2019 CY - Portland, OR, USA DA - 14.07.2019 KW - Ultrasound KW - Coda wave interferometry KW - Concrete KW - Nonlinear KW - Monitoring PY - 2019 AN - OPUS4-48688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Seismic methods to test concrete strcutures N2 - Seismic methods are increasingly used to improve ultrasonic imaging and monitoring of concrete. At BAM, we are research mainly the use of Reverse Time Migration to get better images from ultrasonic echo data of thick, complex concrete structures. Coda wave interferometry is used to detect subtle changes in concrete constructions, e. g. using embedded ultasonic transducers. T2 - Geophysikalisches Seminar der Universität Potsdam CY - Potsdam,. Germany DA - 25.01.2019 KW - Concrete KW - Ultrasound KW - Monitoring KW - Imaging PY - 2019 AN - OPUS4-47302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultrasonic monitoring of structural concrete elements N2 - Ultrasonic transmission measurements are used to monitor concrete elements mostly on a laboratory scale since decades. Recently, coda wave interferometry, a technique adapted from seismology, has been introduced to civil engineering experiments. It can be used to reveal subtle changes in concrete samples and even large construction elements without having a transducer directly at the location where the change is taking place. The methodology works best with embedded transducers to avoid coupling issues or excessive environmental influence. These transducers can be used for newly built and existing structures. Recently, large concrete beams have been equipped with a network of transducers and loaded until failure. Using code wave interferometry, it was possible to visualize stress fields and damaged areas. This paper gives an overview of the state of the art, recent results achieved at BAM and a task list for further results and development. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.03.2019 KW - Concrete KW - Ultrasound KW - Monitoring KW - coda wave interferometry PY - 2019 AN - OPUS4-47676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hafiz, A. A1 - Schumacher, T. A1 - Dusicka, P. T1 - Post-earthquake damage evaluation of concrete strucutres using ultrasonic monitoring: A proof-of concept laboratory study N2 - In earthquake-prone regions such as the Pacific Northwest, damage assessment tools are needed to enable safety evaluations to support recovery. Currently, damage assessment is performed primarily by visual inspection and is often impossible for structural members that are inaccessible, such as deep foundations or interior members hidden by cladding. This study explores the possibility of using embedded ultrasonic transducers to monitor reinforced concrete members for damage progression under earthquake loading. A novel methodology is proposed where changes in the member condition due to an increase in the earthquake-type loading of a full-scale column-foundation specimen are correlated with changes in the recorded ultrasonic waveforms. The discussed preliminary analysis of the ultrasonic signals is based on wave propagation velocity, changes in the coda wave portion, and maximum amplitude of the signals. Three embedded transducers were used to continuously monitor the laboratory specimen during destructive testing. This paper provides an overview of the proposed methodology, outlines the laboratory experiment, and discusses some preliminary observations. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.3.2019 KW - Concrete KW - Ultrasound KW - Monitoring KW - Earthquake PY - 2019 AN - OPUS4-47678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abraham, O. A1 - Niederleithinger, Ernst A1 - Chapeleau, X. A1 - Klikowicz, P. A1 - Brühwiler, E. A1 - Bassil, A. A1 - Wang, Xin A1 - Chakraborty, J. A1 - Bayane, I. A1 - Leduc, D. A1 - Salamak, M. A1 - Katunin, A. A1 - Sørensen, J.D. T1 - Addressing the need to monitor concrete fatigue with nondestructive testing: Results of infrastar European project N2 - Fatigue is one of the most prevalent issues, which directly influences the service life expectancy of concrete structures. Fatigue has been investigated for years for steel structures. However, recent findings suggest that concrete structures may also be significantly subjected to fatigue phenomena that could lead to premature failure of certain structural elements. To date, fatigue of reinforced concrete has been given little focus. Knowledge on the influence factors and durability/capacity effects on this material should be improved. Current technological means to measure fatigue in civil structures like bridges and wind turbines (both onshore and offshore) are outdated, imprecise and inappropriate. Meanwhile, this topic has got much more attention as time-variant loading on concrete structures plays an increasing role, e.g. in bridges with increasing traffic and heavier trucks, and for wind turbines for renewable energy production, e.g. for offshore wind turbine support structures affected by wind and waves. The European Innovative Training Networks (ITN) Marie Skłodowska-Curie Actions project INFRASTAR (Innovation and Networking for Fatigue and Reliability Analysis of Structures - Training for Assessment of Risk) provides research training for 12 PhD students. The project aims to improve knowledge for optimizing the design of new structures as well as for more realistic verification of structural safety and more accurate prediction of the remaining fatigue lifetime of existing concrete structures. First, the INFRASTAR research framework is detailed. Then it will be exemplified through the presentation of the major results of the four PhD students involved in the work package dealing with auscultation and monitoring. This includes the development and improvement of Fiber Optics (FO) and Coda Wave Interferometry (CWI) for crack sizing and imagery, new sensor technologies and integration, information management, monitoring strategy for fatigue damage investigation and lifetime prediction. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - Concrete KW - Fatigue KW - Crack KW - Monitoring KW - Non-destructive testing PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 2 EP - 13 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47237 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - Multi-sensor conception for safe sealing structures in underground repositories N2 - The project "SealWasteSafe" of the Bundesanstalt für Materialforschung und -prüfung (Berlin) deals with sealing structures applied for underground disposal of nuclear waste from two perspectives: material improvement for application in sealing constructions and feasibility study regarding multi-sensor approaches to ensure quality assurance and long-term monitoring. One specimen of 150 l made of alkali-activated material, which was found innovative and suitable for sealing constructions based on preliminary laboratory studies, and another one made of conventional salt concrete, are manufactured with an integrated multi-sensory setup for quality assurance and long-term-monitoring. The specimens were left in their cast form and additionally thermally insulated to simulate the situation in the repository. The multi-sensory concept comprises RFID technology embedded in the specimens suppling material temperature and moisture measurements, integrated distributed fibre optic sensing allowing strain measurement and acoustic emission testing for monitoring crack formation. Overall, the suitability and the functionality of the sensors embedded into and attached to strongly alkaline (pH > 13 for the AAM) and salt corrosive (NaCl) environment was proven for the first 672 h. First RFID measurement succeeded after 626 h for the alkali-activated material and after 192 h for the conventional salt concrete. Strain measurement based on fibre optic sensing turned out the alkali-activated material (> 1 mm/m) undergoing approximately twice the compression strain as the salt concrete (< 0.5 mm/m). In contrast, the acoustic emission first and single hits representing crack formation in numbers, was found for alkali-activated material half of that detected at the salt concrete. T2 - SMIRT 26 CY - Berlin, Germany DA - 10.07.2022 KW - SealWasteSafe KW - Monitoring KW - Acoustic emission KW - Fibre optic sensing KW - RFID technology KW - Alkali-activated material PY - 2022 AN - OPUS4-55372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Current Trends in SHM of German Prestressed Concrete Road bridges N2 - Due to increasing ageing, deterioration and loading , several prestressed concrete bridges bulit in the 1950ies and 1960ies need monitoring. Recently several bridges have sucesssfully equipped with acoustic emission sensing system. BAM works together with several universities on an add onn: Active ultrasonic monitoring combined with coda wave interferometry will help to detect subtle changes and precursors fo failure earlier than other methods. T2 - TRB 100th Annual Meeting, Subcommittee AKT40(3) CY - Online meeting DA - 05.01.2021 KW - Bridges KW - Monitoring KW - Acoustic emission KW - Ultrasound KW - Coda wave interferometry PY - 2021 AN - OPUS4-51972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Towards digital tools for waste package and facility monitoring and prediction N2 - To provide better means for a safe and effective monitoring of cemented waste packages including prediction tools to assess the future integrity development during pre-disposal activities, several digital tools are evaluated and improved in the frame of the EC funded project PREDIS. Safety enhancement (e. g. less exposure of testing personnel) and cost effectiveness are part of the intended impact. The work includes but is not limited to inspection methods such as muon imaging, wireless sensors integrated into waste packages as well as external package and facility monitoring such as remote fiber optical sensors. The sensors applied will go beyond radiation monitoring and include Proxy parameters important for long term integrity assessment (e. g. internal pressure). Sensors will also be made cost effective to allow the installation of much more sensors compared to current practice. The measured data will be used in digital twins of the packages for specific simulations (geochemical, integrity) providing a prediction of future behavior. Machine Learning techniques trained by the characterization of older packages will help to connect the models to the actual data. All data (measured and simulated) will be collected in a joint data base and connected to a decision framework to be used at actual facilities. The presentation includes detailed information about the various tools under consideration, their connection and first results of our research. T2 - DigiDecom 2021 DIGITAL – Online event focusing on innovation within nuclear decommissioning CY - Online Meeting DA - 23.03.2021 KW - Radioactive waste KW - Waste package KW - Monitoring KW - Digital twin PY - 2021 AN - OPUS4-52622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultrasonic coda wave monitoring of concrete structures: First experiences with large-scale experiments and real structures N2 - Ultrasonic monitoring, making use of the sensitivity of the coda of repeated transmission meas-urements to changes in stress, temperature, moisture, as well as localized or distributed damage, has gotten at-tention in structural health monitoring (SHM) research recently. Analysis methods such as coda wave inter-ferometry (CWI), including its nonlinear extension, have been shown to be able to measure ultrasonic wave velocity changes with a 1∙10-5 resolution, while indicators such as cross-correlation or cross-coherence have been used to distinguish between reversible and irreversible changes. Several small- and large-scale laboratory experiments have demonstrated that stress changes in structures can be captured or damage detected in a very early stage. The use of this technique for pre-warning before failure are currently under investigation, as well as detailed research on the physical causes and the connection between ultrasonic wave properties and materi-al/structural behavior. Recently, several of large-scale laboratory and real structures have been instrumented with embedded ultrasonic transducers to gather experience and evidence on how to use this technology in re-al-world applications. Preliminary results from installations on a new bridge, an existing bridge, a tunnel, a la-boratory earthquake test as well as a historic stadium in Germany, Poland, and the United States, respectively, are presented. Environmental influences (mainly temperature) and validation by load tests are discussed. T2 - IABMAS 2020 CY - Online meeting DA - 11.04.2021 KW - Ultrasound KW - Monitoring KW - Coda wave interferometry KW - Concrete KW - Bridges PY - 2021 AN - OPUS4-54167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Digital tools for cemented waste package and facility monitoring and prediction N2 - To provide better means for a safe and effective monitoring of cemented waste packages including prediction tools to assess the future integrity development during pre-disposal activities, several digital tools are evaluated and improved in the frame of the EC funded project PREDIS. Safety enhancement (e. g. less exposure of testing personnel) and cost effectiveness are part of the intended impact. The work includes but is not limited to inspection methods such as muon imaging, wireless sensors integrated into waste packages as well as external package and facility monitoring such as remote fiber optical sensors. The sensors applied will go beyond radiation monitoring and include proxy parameters important for long term integrity assessment (e. g. internal pressure). Sensors will also be made cost effective to allow the installation of much more sensors compared to current practice. The measured data will be used in digital twins of the packages for specific simulations (geochemical, integrity) providing a prediction of future behavior. Machine Learning techniques trained by the characterization of older packages will help to connect the models to the actual data. All data (measured and simulated) will be collected in a joint data base and connected to a decision framework to be used at actual facilities. The paper includes detailed information about the various tools under consideration, their connection and first results of our research. T2 - International Conference on Radioactive Waste Management: Solutions for a Sustainable Future CY - Vienna, Austria DA - 01.11.2021 KW - Radioactive waste disposal KW - Monitoring KW - Cemented waste PY - 2021 AN - OPUS4-54163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - SealWasteSafe: materials technology, monitoring techniques, and quality assurance for safe sealing structures in underground repositories N2 - Within the project SealWasteSafe, we advance construction materials and monitoring concepts of sealing structures applied for underground disposal of nuclear or toxic waste. As these engineered barriers have high demands concerning integrity, an innovative alkali-activated material (AAM) is improved and tested on various laboratory scales. This AAM has low reaction kinetics related to a preferential slow release of the heat of reaction in comparison to alternative salt concretes based on Portland cement or magnesium oxychloride cements. Hence, crack formation due to thermally induced strain is reduced. After successful laboratory scale analysis (Sturm et al., 2021), the AAM is characterised on a larger scale by manufacturing test specimens (100–300 L). Conventional salt concrete (DBE, 2004) and the newly developed AAM are compared using two specimen geometries, i.e. cylindrical and cuboid. A comprehensive multisensor monitoring scheme is developed to compare the setting process of AAM and salt concrete for these manufactured specimens. The analysed parameters include temperature and humidity of the material, acoustic emissions, and strain variations. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete, enable wireless access to temperature and humidity measurements and are compared to conventional cabled systems. Additionally, fibre-optic sensors (FOS) are embedded to record strain, but also have potential to record temperature and moisture conditions. Part of this project aims at demonstrating the high reliability of sensors and also their resistance to highly alkaline environments and to water intrusion along cables or at sensor locations. Further technical improvements were implemented so that first results clearly show the scalability of the setting process from previous small-scale AAM experiments and particularly the high potential of the newly developed approaches. Furthermore, ultrasonic methods are used for quality assurance to detect obstacles, potential cracks and delamination. On the one hand, both active and passive ultrasonic measurements complement the results obtained from the multisensor monitoring scheme for the produced specimens. On the other hand, the unique large aperture ultrasonic system (LAUS) provides great depth penetration (up to nearly 10 m) and can thus be applied at in situ sealing structures built as a test site in Morsleben by the Federal Company for Radioactive Waste Disposal (Bundesgesellschaft für Endlagerung, BGE) as shown by Effner et al. (2021). An optimised field lay-out identified from forward modelling studies and advanced imaging techniques applied to the measured data will further improve the obtained results. To characterise the inside of the test engineered barrier and achieve a proof-of-concept, an ultrasonic borehole probe is developed to enable phased arrays that can further improve the detection of potential cracks. Modelling results and first analysis of semispherical specimens confirmed the reliability of the directional response caused by the phased arrays of the newly constructed ultrasonic borehole probe. Overall, the project SealWasteSafe improves the construction material, multisensor monitoring concepts and ultrasonics for quality assurance. This will help to develop safe sealing structures for nuclear waste disposal. The outcomes are particularly valuable for salt as a host rock but partly also transferrable to alternative conditions. T2 - Safe ND Interdisciplinary research symposium on the safety of nuclear disposal practices CY - Berlin, Germany DA - 10.11.2021 KW - Borehole probe KW - SealWasteSafe KW - Engineered barrier KW - Materials technology KW - AAM KW - Monitoring KW - Ultrasound PY - 2021 AN - OPUS4-53919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - New materials and innovative monitoring for safe sealing structures in underground repositories N2 - Within the project SealWasteSafe, we advance construction materials and monitoring concepts of sealing structures applied for underground disposal of nuclear waste. As these engineered barriers have high demands concerning integrity, an innovative alkali-activated material (AAM) is improved and tested on various laboratory scales that is highly suitable for the application in salt as a host rock. This AAM has a low reaction kinetics related to a preferential slow release of the heat of reaction in comparison to alternative salt concretes based on Portland cement or magnesium oxychloride cements. Hence, crack formation due to thermally induced strain is reduced. A comprehensive multi-sensory monitoring scheme is developed and investigated to compare the setting process of AAM and salt concrete for manufactured specimens (100-300 l). The analysed parameters include temperature and humidity of the material, acoustic emissions, and strain variations recorded by fiber optic cables. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete allow for wireless access and are compared to conventional cabled systems for temperature and humidity measurements. Furthermore, ultrasonic methods are used for quality assurance to detect obstacles, potential cracks and delamination. Field layout and applied imaging techniques are optimised to enhance the image quality. To characterise the inside of the test engineered barrier and achieve a proof-of-concept, an ultrasonic borehole probe is developed to allow for phased arrays that can further improve the detection of potential cracks. Modelling results and first analysis of half-spherical specimen prove the reliability of the directional response caused by the phased arrays of the newly constructed ultrasonic borehole probe. Overall, the project SealWasteSafe improves the construction material, multi-sensory monitoring concepts and ultrasonics for quality assurance. Particularly for salt as a host rock, this will help to develop safe sealing structures for nuclear waste disposal. T2 - 9th IGD-TP Symposium CY - Zurich, Switzerland DA - 20.09.2022 KW - SealWasteSafe KW - Monitoring KW - Engineered barrier systems KW - Alkali-activated material KW - Ultrasonic inspection PY - 2022 AN - OPUS4-55826 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maack, Stefan T1 - Recent advances in (ultra)sonic active and passive monitoring of reinforced and prestressed concrete structures N2 - In addition to already established structural monitoring methods such as deformation, inclination or strain gauges or acoustic emission sensors, sonic or ultrasonic monitoring might provide valuable information about the condition or alteration of a structure. Sensors such as geophones, recording ambient noise in the sonic and subsonic frequency range can provide information beyond modal analysis by using interferometric methods. Wave velocities determined by this method are related to the elastic properties and stiffness of material and structure and can be converted into damage indicators. Embedded active ultrasonic transducer networks can provide more detailed insight about deterioration or damages again, using interferometric technologies. This approach is extremely sensible, detecting relative change in velocity on down to 10-5. These methods, including benefits and remaining challenges, are demonstrated using data from a test structure at BAM’s test site demonstrating the case of prestress loss, and data from an actual bridge still under traffic. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2022) CY - Cape Town, South Africa DA - 03.10.2022 KW - Monitoring KW - Ultrasonic KW - Non-destructive testing KW - Coda wave KW - Bridge PY - 2022 AN - OPUS4-56000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Acoustic emission and ultrasonic monitoring of a prestressed concrete bridge in its final years N2 - Many European bridges built in the 1950s, 60s and 70s must be re-placed in the next decade due to structural deficiencies, insufficient load capacity or other issues. However, the existing bridges must be used for another couple of years even if flaws and damages already have been detected. In Germany, several prestressed concrete bridges have been instrumented with acoustic emission detection systems to detect wire breaks and to provide early warning signs before failure. To evaluate and interpret the consequences of wire breaks additional instrumentation and accompanying measures as finite element modeling are required. At a bridge in southern Germany we have complemented such a system with active ultrasonic monitoring. Repeated ultrasonic measurements are evaluated with a very sensible algorithm called coda wave interferometry. This method, inspired by seismology, has been shown to deliver early warning signs in lab experiments. Large volumes of concrete can be monitored with a limited network of ultrasonic transducers. We will report on the installation, capabilities, and lim-itations as well as first results. T2 - 1st Conference of the European Association on Quality Control of Bridges and Structures (Eurostruct) CY - Padua, Italy DA - 29.08.2021 KW - Bridge KW - Concrete KW - Acoustic emission KW - Ultrasound KW - Monitoring PY - 2021 AN - OPUS4-54160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Hille, Falk A1 - Hofmann, Detlev A1 - Kind, Thomas ED - Isecke, B. ED - Krieger, J. T1 - Überwachung der Brücke Altstädter Bahnhof, Brandenburg./H. Begleituntersuchungen mit moderner Sensorik und zerstörungsfreier Prüfung N2 - Die B1 Brücke am Altstädter Bahnhof in Brandenburg an der Havel wurde im Dezember 2019 aufgrund von während einer turnusmäßigen Inspektion entdeckten Rissen und Hohlstellen entlang der vorgespannten Längsträger gesperrt und im Mai 2021 abgebrochen. In der Zwischenzeit wurde die Brücke detailliert überwacht. Vor dem Abriss wurden zudem umfangreiche Untersuchungen zur Bestandsaufnahme und Schadensanalyse sowie Tests moderner Sensorik vorgenommen. Dabei konnte sowohl die richtige, zuvor nicht sicher bekannte Anzahl von Spanngliedern in den Querträgern sicher ermittelt werden als auch durch moderne Varianten der Schwingungsmessungen und der faseroptischen Sensorik zusätzliche Kenntnisse püber das Bauwerksverhalten ermittelt werden . In dem Beitrag werden die Verfahren mit ihren Möglichkeiten und Grenzen vorgestellt, die Ergebnissee an der Brücke in Brandenburg erläutert und zukünftige Einsatzmöglichkeiten diskutiert. T2 - 5. Brückenkolloquium CY - Ostfildern, Germany DA - 06.09.2022 KW - Monitoring KW - Brücke KW - Radar KW - Vibration KW - Faseroptik PY - 2022 SN - 978-3-8169-3549-0 SP - 555 EP - 566 PB - Expert Verlag CY - Tübingen AN - OPUS4-55627 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Hicke, Konstantin A1 - Bernauer, F. A1 - Igel, H. A1 - Hadziioannou, C. A1 - Niederleithinger, Ernst ED - Isecke, B. ED - Krieger, J. T1 - Multi-Sensor measurements on a large-scale bridge model N2 - This contribution introduces an investigation of a large-scale prestressed concrete bridge model (“BLEIB” structure at the BAM-TTS open air test site) by means of on-site cooperative measurements. This bridge has an external post-tensioning system and has been instrumented with the ultrasonic transducers, temperature sensors and optical fibers for Distributed Acoustic Sensing (DAS). Our experiment was designed to test the suitability of the novel 6C sensors developed within the framework of the GIOTTO project – the IMU50. The IMU50 sensor enables vibration measurements in translation along three axes and rotation around three axes. The geophone sensors were considered for complementary measurements of vertical velocity response. In the experiment, several perturbations were achieved by controlling the external influence factors such as loading and prestressing changes. The aim of the integrated measurement strategy was to fully observe the results of the condition change and to verify the effectiveness of multiple sensors for bridge monitoring. T2 - 5. Brückenkolloquium CY - Ostfildern, Germany DA - 06.09.2022 KW - Concrete KW - Bridge KW - Monitoring KW - Rotation KW - Distributed acoustic sensing PY - 2022 SN - 978-3-8169-3549-0 SP - 223 EP - 230 PB - Expert Verlag CY - Tübingen AN - OPUS4-55625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Überwachung der Brücke Altstädter Bahnhof, Branden-burg./H. N2 - Die B1 Brücke am Altstädter Bahnhof in Brandenburg an der Havel wurde im Dezember 2019 aufgrund von während einer turnusmäßigen Inspektion entdeckten Rissen und Hohlstellen entlang der vorgespannten Längsträger gesperrt und im Mai 2021 abgebrochen. In der Zwischenzeit wurde die Brücke detailliert überwacht. Vor dem Abriss wurden zudem umfangreiche Untersuchungen zur Bestandsaufnahme und Schadensanalyse sowie Tests moderner Sensorik vorgenommen. Dabei konnte sowohl die richtige, zuvor nicht sicher bekannte Anzahl von Spanngliedern in den Querträgern sicher ermittelt werden als auch durch moderne Varianten der Schwingungsmessungen und der faseroptischen Sensorik zusätzliche Kenntnisse püber das Bauwerksverhalten ermittelt werden . In dem Beitrag werden die Verfahren mit ihren Möglichkeiten und Grenzen vorgestellt, die Ergebnissee an der Brücke in Brandenburg erläutert und zukünftige Einsatzmöglichkeiten diskutiert. T2 - 5. Brückenkolloquium CY - Ostfildern, Germany DA - 06.09.2022 KW - Monitoring KW - Brücke KW - Radar KW - Vibration KW - Faseroptik PY - 2022 AN - OPUS4-55628 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Niederleithinger, Ernst T1 - Multi-Sensor measurements on a large-scale bridge model N2 - This contribution introduces an investigation of a large-scale prestressed concrete bridge model (“BLEIB” structure at the BAM-TTS open air test site) by means of on-site cooperative measurements. This bridge has an external post-tensioning system and has been instrumented with the ultrasonic transducers, temperature sensors and optical fibers for Distributed Acoustic Sensing (DAS). Our experiment was designed to test the suitability of the novel 6C sensors developed within the framework of the GIOTTO project – the IMU50. The IMU50 sensor enables vibration measurements in translation along three axes and rotation around three axes. The geophone sensors were considered for complementary measurements of vertical velocity response. In the experiment, several perturbations were achieved by controlling the external influence factors such as loading and prestressing changes. The aim of the integrated measurement strategy was to fully observe the results of the condition change and to verify the effectiveness of multiple sensors for bridge monitoring. T2 - 5. Brückenkolloquium CY - Ostfildern, Germany DA - 06.09.2022 KW - Concrete KW - Bridge KW - Monitoring KW - Rotation KW - Distributed acoustic sensing PY - 2022 AN - OPUS4-55626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - Multi-sensory monitoring and ultrasound for quality assurance at underground sealing structures N2 - Within the safety concepts of underground disposal sites of nuclear waste, engineered barriers play an important role. As these sealing structures have high demands concerning integrity, we aim at advancing the available construction materials, monitoring and inspection techniques within the project SealWasteSafe. After successful laboratory analysis on the cm-scale, cylindrical and cuboid specimens on the m-scale are produced from classical salt concrete and a specifically developed alkali-activated material. A comprehensive multi-sensory monitoring scheme is applied to compare the setting process of both materials and to demonstrate the sensors’ resistance to highly alkaline environments. Besides temperature and humidity of the materials, strain variations using fibre optic sensors and acoustic emissions are recorded over periods of at least 28 days, partly for more than 8 months. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete allow for wireless access to temperature and humidity measurements and are compared to conventional cabled systems. After hardening and removal of the outer casings of the specimens, further non-destructive evaluations using ultrasonic echo and thermographic measurements are conducted. Preliminary results clearly highlight differences between the tested materials, particularly showing lower acoustic emission activity for the newly developed alkali-activated material potentially indicating less phase changes or cracks. Complementary, ultrasonic methods are improved to be used for quality assurance to detect obstacles, potential cracks and delamination at in-situ sealing structure scale. A unique large aperture ultrasonic system (LAUS) with depth penetration as large as 9 m has already successfully been applied at the test site in Morsleben, Germany, of the federal company for radioactive waste disposal (BGE). Modelling studies help to further optimize the measurement layout. Advanced imaging techniques applied to the modelled and measured data will further improve the obtained images of internal structures. Additionally, an ultrasonic borehole probe is developed and constructed using phased arrays to further enhance the detection of potential cracks. Modelling and preliminary results from laboratory specimens prove the feasibility and potential of the directional response even in heterogeneous material such as concrete. Final investigations under in-situ conditions at the test site of the sealing structure are planned. Overall, the project SealWasteSafe improves the construction material, multi-sensory monitoring, and ultrasound for quality assurance to allow for the development of safe nuclear sealing structures. Although the techniques are tailored for sealing structures within salt as a host rock, they are transferrable to a wider field of applications and alternative disposal conditions. T2 - NDE NucCon CY - Espoo, Finland DA - 25.01.2023 KW - SealWasteSafe KW - Engineered barriers KW - Monitoring KW - Embedded sensors KW - Ultrasonic imaging PY - 2023 AN - OPUS4-56927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera T1 - Sichere Verschlussbauwerke mittels innovativer Materialien, multisensorischem Monitoring und Ultraschall-Prüfung zur Qualitätssicherung N2 - Verschlussbauwerke sind für die untertägige Endlagerung im Salzgestein als eine wichtige technische Barriere vorgesehen. Diese Bauwerke müssen hohen Anforderungen an Sicherheit und Integrität genügen, weshalb im Projekt SealWasteSafe Werkstofftechnik, Prüfverfahren und Überwachungsmethoden für sichere Verschlussbauwerke verbessert werden. Dabei zeigen die untersuchten alkaliaktivierten Materialien (AAM) langsamere Reaktionskinetik bei der Erhärtung im Vergleich zu Salzbeton, was potenziell geringere Rissbildung erwarten lässt. Die Erhärtung wird an Probekörpern (100-300 l) multisensorisch über einen Zeitraum von mindestens 28 Tagen überwacht. Die Parameter Temperatur und Feuchtigkeit werden einerseits kabelgebunden, andererseits mittels drahtloser Radio Frequency Identification (RFID)-Technik aufgezeichnet. Zusätzlich kommen Schallemissionsmessungen sowie Dehnungsmessungen mittels verteilter faseroptischer Sensorik (FOS) zum Einsatz. Die Überwachung zeigt verschiedene Charakteristika beim Erhärten der Materialien mit geringerer Temperaturentwicklung des AAM. Zusätzlich werden Ultraschallmessungen genutzt, um Einbauteile und Störstellen wie Risse und Delaminationen im Rahmen der Qualitätssicherung am Probekörper und am Verschlussbauwerk zu detektieren. Dafür werden sowohl ein Ultraschallmesssystem mit großer Apertur (LAUS) als auch eine Ultraschall-Bohrlochsonde eingesetzt. Durch Erhöhung des Schalldrucks und Schallfeldbündelung im Beton wird die Aussagekraft der von der Bohrlochsonde aufgezeichneten Messsignale verbessert, was in Modellierungen und ersten Labortests gezeigt werden kann. Die Auswertung der Ultraschallmessungen zeigt das große Potenzial der Methode mit Eindringtiefen bis zu 9 m, wobei anspruchsvolle Abbildungsverfahren zu einer verbesserten Abbildung der internen Strukturen führen. Insgesamt verbessern die im Projekt SealWasteSafe entwickelten Materialien und Methoden die Möglichkeiten für sichere Verschlussbauwerke nuklearer Endlager. Obwohl die Konzepte speziell für Bauwerke im Salzgestein entwickelt werden, sind sie partiell gut auf andere Wirtsgesteine übertragbar. T2 - 3. Tage der Standortauswahl CY - Aachen, Germany DA - 08.06.2022 KW - SealWasteSafe KW - Salzbeton KW - Verschlussbauwerke KW - Monitoring KW - Ultraschall KW - Inspektion PY - 2022 AN - OPUS4-55093 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prabhakara, Prathik T1 - Construction and Simulation of a Novel Phased Array Borehole Probe for Ultrasonic Investigations at Sealing Structures in Radioactive Repositories N2 - A novel ultrasonic borehole probe is developed for the quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The goal is to examine the sealing structures made of salt concrete for possible cracks, delamination, and embedded objects. A prototype probe uses 12 individual horizontal dry point contact (DPC) shear wave transducers separated by equidistant transmitter/receiver arrays of six individual transducers each. It is operated with a commercially available portable ultrasonic flaw detector used in the civil engineering industry. To increase the generated acoustic pressure of the borehole probe, the number of transducers in the novel probe is increased to 32. In addition, a timed excitation of each probe directs a focused beam of sound to a specific angle and distance based on calculated time delays. This limits the sensitive test volume and improves the signal-to-noise ratio of the received signals. This paper presents the validation of the newly developed phased array borehole probe by investigating the directivity through beam computation in the CIVA software and experimental investigations on a semi-cylindrical test specimen. It is expected that an optimised radiation pattern of the probe in combination with geophysical reconstruction methods will improve the signal quality and thus increase the reliability of the imaging results. This is of great importance for the construction of safe sealing structures needed for the disposal of radioactive or toxic waste. T2 - ISNT NDE 21 CY - Online meeting DA - 09.12.2021 KW - Borehole probe KW - Engineered barrier KW - Phased array technique KW - SealWasteSafe KW - Monitoring PY - 2022 AN - OPUS4-54498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -