TY - JOUR A1 - Dominguez-Bureos, Marco A1 - Sens-Schönfelder, Christoph A1 - Niederleithinger, Ernst A1 - Hadziioannou, Céline T1 - Stress- and Time-dependent Variations of Elastic Properties for Integrity Assessment in a Reinforced Concrete Test Bridge N2 - In lab experiments, it has been observed that the stress–and time-dependent elastic properties of a complex material at a structural scale perform accordingly to its composition at a microstructural level. We seek complementary practices to the current wavefield-based non-destructive testing techniques to assess not only the integrity level of civil structures but also the microstructural elements that contribute to it. In this paper, we study the systematic evolution of elastic properties of concrete as an alternative to investigate the density of micro imperfections in an outdoor-conditioned concrete structure. We estimate 5-second relative velocity changes in four locations on a Test bridge subjected to the action of vertical impulsive sources, at different prestressing levels (dynamic effects at different static conditions). We describe the structure’s stress- and time-dependent elastic response by means of acoustoelastic effect and Slow-dynamic processes, respectively. We also estimate the conventional ultrasound pulse velocity and perform a cooperative integrity analysis of the structure using the three elastic phenomena. Our findings reveal: 1) The presence of soft microstructures and their orientation’s influence on the acoustoelastic effect and Slow-dynamics in field-conditioned concrete structures. 2) The relation of low ultrasound pulse velocities with high acoustoelastic effect and high magnitudes and variability of Slow-dynamics. 3) Different elastic behaviours on the north and south spans of the bridge, suggesting different heterogeneity levels on the analysed locations of the concrete beam. KW - Concrete KW - Ultrasound KW - Nonlinear KW - Elastic properties KW - Damage PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640064 DO - https://doi.org/10.1007/s10921-025-01257-y SN - 0195-9298 VL - 44 IS - 4 SP - 1 EP - 16 PB - Springer Science and Business Media LLC AN - OPUS4-64006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - X-rays without X-rays: Can muon tomography provide pictures from within concrete and other objects? N2 - Until the 1980s radiography was used to inspect civil structures in case of special demands and showed a much better resolution than other NDT techniques. However, due to safety concerns and cost issues, this method is almost never used anymore. Meanwhile, non-destructive techniques such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and accuracy, imaging artefacts or restrictions in detecting certain features when applied to reinforced or prestressed concrete inspection. Muon tomography has received much attention recently. Muons are particles generated naturally by cosmic rays in the upper atmosphere and pose no risk to humans. Novel detectors and tomographic imaging algorithms have opened new fields of application, mainly in the nuclear sector, but also in spectacular cases such as the Egyptian pyramids. As a first step towards practical application in civil engineering and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results have been at least of similar quality compared to ultrasonic and radar imaging, potentially even better. Recently, the research was expanded to more realistic testing problems such as the detection of voids in certain structural elements. However, before practical implementation, more robust, mobile, and affordable detectors would be required as well as user-Friendly imaging and simulation software. The talk also discusses other applications , such as volcanology, mining and geothermal exploration. T2 - RWTH Aachen, Geophysikalisches Seminar CY - Aachen, Germany DA - 11.01.2024 KW - Muon tomography KW - Civil engineering KW - Mining KW - Geothermal engineering PY - 2024 AN - OPUS4-59349 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - X-rays without X-rays: Can muon tomography provide pictures from within concrete objects? N2 - Until the 1980s radiography was used to inspect civil structures in case of special demands and showed a much better resolution than other NDT techniques. However, due to safety concerns and cost issues, this method is almost never used anymore. Meanwhile, non-destructive techniques such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and accuracy, imaging artefacts or restrictions in detecting certain features when applied to reinforced or prestressed concrete inspection. Muon tomography has received much attention recently. Muons are particles generated naturally by cosmic rays in the upper atmosphere and pose no risk to humans. Novel detectors and tomographic imaging algorithms have opened new fields of application, mainly in the nuclear sector, but also in spectacular cases such as the Egyptian pyramids. As a first step towards practical application in civil engineering and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results have been at least of similar quality compared to ultrasonic and radar imaging, potentially even better. Recently, the research was expanded to more realistic testing problems such as the detection of voids in certain structural elements. However, before practical implementation, more robust, mobile, and affordable detectors would be required as well as user-Friendly imaging and simulation software. T2 - ISNT NDE 2023 CY - Pune, India DA - 07.12.2023 KW - Muon tomography KW - Concrete KW - Civil engineering PY - 2023 AN - OPUS4-59347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - ridge Monitoring by Ultrasonic Coda Wave Interferometry N2 - The built infrastructure ages and requires regular inspection and, when in doubt, monitoring. To ensure that older concrete bridges showing signs of deterioration can be used safely, several innovative monitoring tools have been introduced, including but not limited to optical, fiber-optic, or acoustic emission techniques. However, there are gaps in the portfolio. A sensing technique that covers a wide range of damage scenarios and larger volumes, while still being sensitive and specific, would be beneficial. For about 15 years, research has been conducted on ultrasonic monitoring of concrete structures that goes beyond the traditional ultrasonic pulse velocity test (PV test), mostly using a very sensitive data evaluation technique called coda wave interferometry. At BAM we have developed sensors and instrumentation specifically for this method. We have instrumented a 70-year-old, severely damaged prestressed concrete bridge in Germany in addition to a commercial monitoring system. We have now collected data for almost 3 years. We can show that we can provide information about the stress distribution in the bridge. We have also been able to confirm that there has been no significant additional damage to the bridge since the installation. T2 - ISNT NDE 2023 CY - Pune, India DA - 07.12.2023 KW - Coda wave interferometry KW - Structural health monitoring KW - Ultrasound KW - Concrete KW - Bridges PY - 2023 AN - OPUS4-59346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Zerstörungsfreie Prüfung von Betonkonstruktionen N2 - Der Vortrag behandelt den Stand der Technik bei der zerstörungsfreien Prüfung von Betonkonstruktionen und insbesondere den Stand und die Herausforderungen bei der Digitalisierung. Es werden Prüfaufgaben sowie etablierte Prüfmethoden und die passende Auswahl diskutiert. Ein weitere Schwerpunkt liegt bei der Genauigkeit und Verlässlichkeit und dem Konzept ZfPStatik. Abschließend werden Schnittstellen zu BIM, SIB-Bauwerke und anderen System kurz angerissen und ein Katalog offener Fragen aufgestellt. T2 - Workshop Digitale Bauwerkserhaltung inklusive Bauwerksdiagnose CY - Bonn, Germany DA - 20.02.2024 KW - ZfP-Bau KW - Beton KW - Bauwerksprüfung KW - Digitalisierung KW - ZfPStatik PY - 2024 AN - OPUS4-59547 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chierici, Andrea A1 - Cancemi, Salvatore Angelo A1 - Niederleithinger, Ernst A1 - Lo Frano, Rosa T1 - Enhanced radioactive waste drum monitoring: A sensorized LoRa-based network for identification and integrity assessment N2 - A reliable monitoring and oversight system is essential to guarantee the safe operation and eventual closure of radioactive waste disposal facilities. With recent technological advancements, there is now the capability to deploy distributed wireless sensor networks that are cost-effective and low in power consumption. Such networks are versatile, finding applications in several civil, environmental, and industrial sectors. This work presents a novel system and method for identifying and continuously monitoring the integrity of stored radioactive waste packages. The proposed approach, developed by the University of Pisa in the context of the H2020 European Project PREDIS, employs a network of wireless node devices, provided with solid-state micro-power radiation detectors tasked with the measurement of gamma-rays and thermal neutrons coming from within cemented waste drums. Collected data are automatically transmitted across the storage site via Long Range radio technology and forwarded to cloud-based or offline platforms, allowing for further visualization, data processing, and safe storage. The system highlights the feasibility of autonomously and passively gathering data from radioactive waste drums over extended distances (more than 250 m in non-line-of-sight conditions), decreasing the reliance on portable or automated scanning mechanisms. In line with its capability for autonomous, long-range data collection, the system satisfies the requirement for structural integrity, containment, and confinement of packaging throughout both interim and long-term disposal of radioactive wastes, thereby playing a key role in reinforcing the safe management of radioactive waste. KW - Radioactive waste KW - Integrity monitoring KW - Radiation sensors KW - Cloud storage KW - LoRaWAN PY - 2024 DO - https://doi.org/10.1016/j.nucengdes.2024.113231 SN - 0029-5493 VL - 424 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-60217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Accuracy, Uncertainty, Probability of Detection N2 - This talk presents the concepts of measurement accuracy, uncertainty (in contrast to error analysis) an probability of detection for non-destructive testing. The relevant guidelines (GUM, Mil.Std.) are intrduced and practical examples given. T2 - USES2 Training Week 2 CY - Berlin, Germany DA - 24.06.2024 KW - Uncertainty KW - Pod KW - Measurements PY - 2024 AN - OPUS4-60467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skłodowska, Anna A1 - Lay, Vera A1 - Baensch, Franziska A1 - Niederleithinger, Ernst A1 - Kühne, Hans-Carsten T1 - Acoustic emission monitoring for engineered barriers in nuclear waste disposal N2 - To safely dispose of nuclear waste in underground facilities, engineered barrier systems are needed to seal shafts and galleries. The material used in these barriers must be adapted to the host rock parameters. Shrinking and cracking must be avoided to provide a barrier with almost zero permeability. For repositories in salt rock environments, several types of salt concrete (SC) are possible construction materials. Within the project SealWasteSafe, we compared the behavior of an innovative alkali-activated material (AAM) with standard SC in their hydration and hardening phase. To monitor the microstructural changes within the two materials SC and AAM, acoustic emission (AE) signals have been recorded for up to ~250 days on 340-liter-cubic specimens. The phenomenon of AE is defined as the emission of elastic waves in materials due to the release of localized internal energy. Such energy release can be caused by the nucleation of micro-fracture, e.g., in concrete while curing or when exposed to load. The occurrence of AE events gives first rough indications of microstructural changes and potentially occurring cracking and thus, provides insights for structural health monitoring (SHM). The results show, that for the first 28 days after casting, less AE activity was detected in the AAM compared to SC. After 61 days, in the AAM material, the number of AE events exceeded those observed in the SC. However, the majority of the AE detected and located in AAM was related to surface effects, and not to microstructural changes or occurring cracks within the bulk volume. Additionally, the source location analysis indicated, that despite lower activity in SC, we observed some clustering of the events. In contrast, in AAM, the activity inside the specimen is randomly distributed over the whole volume. The monitoring results help to estimate the material’s sealing properties which are crucial to assess their applicability as sealing material for engineered barriers. T2 - 11th European Workshop on Structural Health Monitoring (EWSHM 2024) CY - Potsdam, Germany DA - 10.06.2024 KW - Acoustic emission monitoring KW - Nuclear waste repositories KW - Event localization KW - SealWasteSafe project PY - 2024 AN - OPUS4-60552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skłodowska, Anna A1 - Lay, Vera A1 - Baensch, Franziska A1 - Niederleithinger, Ernst A1 - Kühne, Hans-Carsten T1 - Microseismicity monitoring in materials for nuclear waste storage repositories N2 - One of the major tasks in nuclear waste management is to design safe and reliable sealing structures for radioactive waste repositories. Particularly for salt as a host rock, engineered barrier systems for underground waste disposal must be constructed of well-understood (cementitious) materials that will sustain environmental conditions and ensure high durability. Within the SealWasteSafe project, we studied two materials with a potential for sealing structures for nuclear waste repositories: an innovative alkali-activated material (AAM) and standard salt concrete (SC). To analyze the development of microstructural changes within the materials, we monitored microseismicity (aka acoustic emission monitoring) occurring during the hardening and setting period in two 340-liter-cubic specimens for up to ~250 days. The monitoring results showed, that in the first 61 days, fewer events occurred in AAM compared to SC. After this time the number of events in AAM sharply increased and significantly exceeded those observed in SC. However, the source localization analysis revealed that the increase of microseismicity in AAM material was not related to the formation of macro-cracks within the material but was mainly caused by the surface effects. Accompanying analysis of the test specimens with additional methods (such as e.g., X-ray CT) proved that no macro-cracks were observed inside the AAM specimen. Further analysis in the time and frequency domains helped to characterize the tested materials and to estimate their potential to be used for engineered barriers in nuclear waste repositories. Overall, our study shows the potential of microseismicity monitoring for feasibility studies and quality assurance in a broad range of applications, also in structural health monitoring. T2 - 84. Jahrestagung der Deutschen Geophysikalischen Gesellschaft CY - Jena, Germany DA - 10.03.2024 KW - Microseismicity KW - Nuclear waste repositories KW - Acoustic emission KW - SealWasteSafe project KW - Salt rock KW - Alkali-activated materia PY - 2024 AN - OPUS4-60549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Muon tomography - ready for practical application? N2 - Security and nuclear safeguards, but not yet in civil engineering. The potential is enormous, as muon tomography could replace traditional X-ray imaging of infrastructure, a method that was popular in the past but has mostly been abandoned due to concerns about radiation safety. In 2020, a report on the first large-scale muon tomography experiment on a reinforced concrete specimen was published. However, robust mobile detectors and faster data acquisition methods are still needed. This is now changing, however. Prototype mobile detectors have been announced or are in development, and data acquisition time has been reduced from weeks to days. This presentation will showcase current developments and focus on a validation experiment at BAM. T2 - NDT-CE 2025 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Izmir, Türkiye DA - 24.09.2055 KW - Muon tomography KW - Bridge inspection KW - Concrete PY - 2025 AN - OPUS4-64256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - ZfP-Bau post Carolabrücke: Chancen und Herausforderungen N2 - Der Einsturz der Carolabrücke hat die Fachwelt, Politik und Öffentlichkeit aufgerüttelt. Während die Diagnose der Ursachen noch andauert (aber wohl zum Vortragzeitpunkt abgeschlossen sein wird), werden erste, nach Ansicht vieler Experten überfällige Konsequenzen gezogen. Zahlreiche Brücken werden vorsichtshalber gesperrt, intensive Prüfungen und Überwachungsmaßnahmen sind veranlasst und werden ausgeweitet. Die Untersuchungsmethodik für Brücken mit dem Verdacht auf Spannungsrisskorrosion und ohne „sicheres“ Ankündigungsverhalten vor Versagen – übrigens keineswegs auf die östlichen Bundesländer beschränkt – steht auf dem Prüfstand. Dabei erhält wohl auch die zerstörungsfreie Prüfung eine veränderte und wichtige Rolle, ebenso wie Methoden zur Dauerüberwachung. Dabei wird aus gutem Grund auf den Stand der Technik zurückgegriffen. Der Vortrag beleuchtet die Rolle der ZfP und die verwendeten Methoden im Rahmen dieser Untersuchungen. Er weist aber auch auf Technologien hin, die in den nächsten Jahren in die Praxis eingeführt werden dürften und zukünftig bei der Untersuchung und Überwachung von Stahl- und Spannbetonbauwerken eine Rolle spielen dürften. T2 - DGZfP Jahrestagung CY - Berlin, Germany DA - 26.05.2025 KW - Zerstörungsfreie Prüfung KW - ZfPBau KW - Brücken KW - Stahlbeton PY - 2025 AN - OPUS4-63230 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - NDT-CE Qualification and Certification N2 - Due to the increased demand for NDT investigations and assessment of energy and traffic infrastructure, a qualification and certification system for NDT personel is urgently needed. Up to now, only Italy, Malaysia and Germany have set up such systems. The talk gives an overview of the demand and current activities, including those of IAEA. T2 - IAEA ICARST 2025 CY - Vienna, Austria DA - 07.04.2025 KW - NDT-CE KW - Qualification KW - Certification PY - 2025 AN - OPUS4-63002 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Condition monitoring for lifetime extension of interim storage facilities N2 - The German interim nuclear storage facilities are designed for a 50 year service life and 40-year operating period. They will be needed much longer, as a final repository will not be available until 2050 at the earliest. The objective of ZuMoBau-ZL is to develop a suitable condition assessment and monitoring concept suitable for the structures in interim storage facilities, including life prediction models, with which the remaining service life can be predicted, verified, and monitored as realistically as possible. T2 - IAEA ICARST 2025 CY - Vienna, Austria DA - 07.04.2025 KW - Nuclear waste KW - Interim storage KW - Liefetime extension KW - Reinforced concrete PY - 2025 AN - OPUS4-62984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skłodowska, Anna A1 - Coronel Subia, Hernan Alejandro A1 - Inzunza Araya, Ernesto A1 - Niederleithinger, Ernst T1 - Influence of velocity changes on acoustic emission monitoring of masonry walls under diagonal compression load N2 - Acoustic emission (AE) is a highly sensitive, non-destructive method which has great potential in damage event detection and assessment in masonry structures exposed to e.g., seismic loads. However, the highly heterogenous nature of the masonry structures and their low densities cause high attenuation and distortion of the signal. Localization of the AE events is challenging because the AE waves propagate through various masonry constituents (i.e., bricks and mortar joints) at different velocities. We present an attempt to locate the sources of AE events from the signals recorded during the diagonal compression loading, and analyze the influence of different wave velocities on its accuracy. T2 - 36th Conference of the European Working Group on Acoustic Emission CY - Potsdam, Germany DA - 18.09.2024 KW - Acoustic emission KW - Masonry KW - Compression test PY - 2024 AN - OPUS4-61689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bertola, Numa A1 - Schumacher, Thomas A1 - Niederleithinger, Ernst A1 - Brühwiler, Eugen T1 - Combining passive and active ultrasonic stress wave monitoring for the characterization of the early-age properties of a UHPFRC beam N2 - This article focuses on the characterization of the early-age properties of Ultra-High-Performance Fiber-Reinforced Cementitious Composite (UHPFRC), which is becoming popular for designing lightweight and durable structures. Due to the large proportion of cement in the mix, the hardening of UHPFRC is significantly faster than conventional concrete. Therefore, the development of UHPFRC properties, such as the elastic modulus, is difficult to monitor as it happens while elements are within the formwork. For this reason, the hydration process of UHPFRC elements is not fully understood yet. A combined passive (or acoustic emission) and active ultrasonic stress wave monitoring approach has the potential to characterize structures made of cementitious materials over their entire service duration. Using a network of embedded ultrasonic transducers, monitoring can start only a few instants after casting. A UHPFRC beam with a T-shaped cross-section and a length of 4.2 m was constructed and instrumented with 24 transducers as well as 15 thermocouples. Monitoring results lead to the characterization of the development of the early-age UHPFRC properties on the structural-element scale while the specimen is within the formwork. The continuous monitoring approach enabled accurate estimations of the spatial and temporal evolution of the modulus of elasticity. Thanks to this novel combination of monitoring techniques, the early age properties of UHPFRC, which were measured at the material scale, are confirmed at the structural scale for the first time. KW - Concrete KW - UHPFRC KW - Acoustic emission KW - Ultrasonic monitoring KW - Coda wave interferometry PY - 2025 DO - https://doi.org/10.1016/j.conbuildmat.2025.140319 SN - 0950-0618 VL - 466 SP - 1 EP - 18 PB - Elsevier Ltd. AN - OPUS4-63448 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Applications of a Multi-Channel Ultrasound System for Assessing Large Concrete Structures N2 - Non-destructive testing (NDT) plays a vital role in the assessment of large concrete structures, where the detection of internal defects is particularly challenging due to size, material heterogeneity and complex geometries. In this study, the use of a multi-channel, large-aperture ultrasound system is demonstrated for improving the ultrasonic pulse-echo method for evaluating these large structures. The large aperture of the ultrasound system allows for broader coverage and enhanced sensitivity to internal features such as cracks, voids, and embedded components within the concrete. By capturing data from multiple channels simultaneously, the system improves both resolution and depth penetration. A weighted sum of the Kirchhoff migration is used to post-process the data, resulting in better visualisation and a more detailed interpretation of the internal condition of the structure. This approach is particularly effective for thick and complex materials where conventional methods face limitations. In addition to the pulse-echo method, time-of-flight (TOF) tomography is used to provide quantitative analysis of internal structures. Time-picking techniques allow for the precise mapping of anomalies within the material, offering insights into the condition of concrete with varying geometries and compositions. Together, these two methods: pulse-echo imaging with the large-aperture multichannel system and TOF tomography imaging, offer different possibilities for assessing the internal condition of large concrete structures. The pulse-echo technique focuses on providing detailed images of structural defects, while the TOF tomography provides quantitative data on internal features. This combined approach offers a comprehensive and reliable method for the assessment of large infrastructures. T2 - ISNT NDE 2024 CY - Chennai, India DA - 12.12.2024 KW - NDT-CE KW - concrete KW - ultrasound KW - imaging KW - Kirchhoff KW - tomography PY - 2024 AN - OPUS4-62204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Sein, Sander A1 - Kervalisvil, Andrei A1 - Wöstmann, Jens A1 - Helm, Marek T1 - Muon tomography - ready for practical application? N2 - Muon tomography uses naturally occurring nuclear particles to 'X-ray' technical objects. It has applications in security and nuclear safeguards, but not yet in civil engineering. The potential is enormous, as muon tomography could replace traditional X-ray imaging of infrastructure, a method that was popular in the past but has mostly been abandoned due to concerns about radiation safety. In 2020, a report on the first large-scale muon tomography experiment on a reinforced concrete specimen was published. However, robust mobile detectors and faster data acquisition methods are still needed. This is now changing, however. Prototype mobile detectors have been announced or are in development, and data acquisition time has been reduced from weeks to days. This presentation will showcase current developments and focus on a validation experiment at BAM. T2 - NDT-CE 2025 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Izmir, Türkiye DA - 24.09.2025 KW - Concrete KW - Muon tomography KW - Inspection PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642517 DO - https://doi.org/10.58286/31696 SN - 1435-4934 VL - 30 IS - 10 SP - 1 EP - 10 PB - ndt.net AN - OPUS4-64251 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, Ute A1 - Emge, Julia A1 - Klein, Samuel A1 - Oswald, Jan A1 - Shpakova, Nina A1 - Stopp, Philipp A1 - Weingard, Christoph A1 - Koster, Dirk A1 - Schönsee, Eric A1 - Hille, Frank A1 - Niederleithinger, Ernst T1 - Development of distributed sensor electronics for energy-efficient and proactive maintenance of buildings N2 - Permanently installed sensor systems are becoming increasingly important for monitoring critical infrastructure. The research institutes Fraunhofer IZFP and BAM, together with industrial partners and users, are developing a concept for an electronic system consisting of an Edge-Gateway as a central high-performance node and a variable number of Sensor-Edge units that establish the connection between the sensors of the permanent monitoring system and the gateway, which also provides connection to a cloud. A software tool allows identification and localization of sensors and visualization of sensor data. The principle of the system is demonstrated using sensors installed in the road surface to monitor traffic loads as an example. Two test structures, a full-scale laboratory at Fraunhofer IZFP, Saarbrücken, and the “BLEIB” reference structure at BAM, test site technical safety (TTS) Horstwalde, were used to demonstrate the principle and the functioning of the electronic system. T2 - NDT-CE 2025 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Izmir, Türkiye DA - 24.09.2025 KW - Edge computing KW - Bridge monitoring KW - Multi-sensor PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642530 DO - https://doi.org/10.58286/31650 SN - 1435-4934 VL - 30 IS - 10 SP - 1 EP - 3 PB - ndt.net AN - OPUS4-64253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Roumia, N. A1 - Niederleithinger, Ernst A1 - Mazotti, C. T1 - Post-tensioned concrete inspection and imaging using 2D and 3D Dry Point Contact ultrasound array N2 - by the asset owners. Advancements were introduced to the method by distributing numerous shear horizontal Dry Point Contact (DPC) transducers in a uniform way, forming a linear array that allows for immediate two-dimensional imaging of the subsurface using Synthetic Aperture Focusing Technique (SAFT). Recent developments were implemented, allowing for the full potential use of the array by means of three-dimensionaldata acquisition instead of two-dimensional. This work provides a practical comparison between the 2D Linear scanning mode and the newly introduced 3D Matrix scanning mode regarding the tendon duct inspection, grouting quality, and reinforcement localization. Imaging the subsurface was performed through research-oriented software, namely InterSAFT, which allows for 2D and 3D imaging using Linear and Matrix data acquisitions. T2 - NDT-CE 2025 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Izmir, Türkiye DA - 24.09.2025 KW - Ultrasound KW - Imaging KW - Concrete KW - SAFT PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642551 DO - https://doi.org/10.58286/31690 SN - 1435-4934 VL - 30 IS - 10 SP - 1 EP - 4 PB - ndt.net AN - OPUS4-64255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Emerging technologies for non destructive testing and monitoring of concrete structures in nuclear facilities N2 - For a long time, practical application of non-destructive testing in civil engineering has been limited on simple (but useful) methods such as rebound hammers, ultrasonic pulse velocity measurements, rebar detectors or potential mapping. Since the late 1990ies new methods and devices have been developed for geometry and damage detection, including radar and ultrasonic echo array techniques which brought progress in condition assessment of buildings and infrastructure assets. However, there are still gaps, especially for massive concrete structures used in nuclear facilities, including lack of penetration depth, resolution, or translation of NDT parameters to engineering properties. Recent research tries to fill these gaps. Currently, new ultrasonic devices with greater penetration depth and better resolution depth are developed, including imaging methods revealing greater details of the interior of concrete constructions. Ultrasonic technologies are also extended to nonlinear methods providing baseline free damage assessment and monitoring capabilities. Another example of a technique with a huge potential for concrete constructions is muon tomography, where first field experiments are underway. A review of the potential and limitations of these methods will be given in the presentation. T2 - IAEA ICARST 2025 CY - Vienna, Austria DA - 07.04.2025 KW - NDT-CE KW - Ultrasound KW - Muography KW - Concrete KW - Emerging PY - 2025 AN - OPUS4-63003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst T1 - Improvement and extension of the parallel seismic method for foundation depth measurement N2 - he parallel seismic (PS) method is used for determination of the unknown or undocumented depth of foundations, mostly piles. It was developed several decades ago and has not much changed since. PS is based on impulse generation on the pile head and registration of travel times in a borehole parallel to the foundation. The method is applicable to many foundation types, including single piles, pile walls, or sheet piles. While the accuracy is known to be high if the distance between foundation and borehole is small, the foundation length is overestimated with increasing distance. This paper presents the results of a systematic study on the influence of geometric and material parameters on the measurement resultsand explains the effects by studying the underlying wave phenomena based on numerical studies. It can be shown that several parameters (e.g. borehole inclination) have a strong influence. Foundation flaws and soil layers have also to be taken into account, while the possibilities in the other direction (derivation of soil parameters or detection of flaws from the results) are limited. Based on the simulation results, a new mathematical algorithm for data interpretation has been developed which takes into Account the soil layers and the borehole inclination. This novel data interpretation scheme was used in combination with different data Inversion methods. The new interpretation method was successfully validated using several sets of simulated data. Not only was it shown to be more accurate than all other available methods, but it also extended the maximum allowable pile–borehole distance to 2–3 m. Today, parallel seismics is the only method applicable on both metallic and non-metallic foundations which can be used without calibration. It has the largest range of all borehole methods. To enhance its efficiency it can be combined with downhole seismic measurements in the very same borehole to retrieve soil parameters. KW - Parallel seismic KW - Length KW - Piles KW - Interpretation KW - Foundations PY - 2012 DO - https://doi.org/10.1016/j.sandf.2012.11.023 SN - 0038-0806 VL - 52 IS - 6 SP - 1093 EP - 1101 PB - Soc. CY - Tokyo AN - OPUS4-27908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grohmann, Maria A1 - Niederleithinger, Ernst T1 - Application of Elastic Reverse Time Migration to Ultrasonic Echo Data from Concrete Structures N2 - To enhance ultrasonic imaging of concrete structures, we adapted the geophysical migration method, Reverse Time Migration (RTM), for non-destructive testing (NDT) in civil engineering. First, two 2D elastic RTM algorithms, each considering different wave types, were implemented and evaluated with synthetic ultrasonic data. The algorithm that best resolved numerical concrete structures was subsequently applied to real ultrasonic data from a concrete specimen. Compared with conventional synthetic aperture focusing technique (SAFT) imaging, elastic RTM reproduced a greater number of structural features in both the numerical model and the concrete specimen. In particular, elastic RTM reconstructed vertical interfaces as well as hidden lower edges of modeled cavities and tendon ducts. Notably, imaging the full cross-sections of tendon ducts, which enables direct diameter estimation, represents a novel achievement for ultrasonic NDT. T2 - NDT-CE 2025 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Izmir, Turkey DA - 24.09.2025 KW - Concrete Structures KW - Ultrasonic Echo Technique KW - Ultrasonic Imaging KW - Elastic Reverse Time Migration KW - Synthetic Aperture Focusing Technique PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650350 DO - https://doi.org/10.58286/31680 SN - 1435-4934 SP - 1 EP - 3 PB - e-Journal of Nondestructive Testing CY - www.ndt.net AN - OPUS4-65035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Giese, Lutz A1 - Weritz, Friederike A1 - Weimann, Karin A1 - Niederleithinger, Ernst A1 - Ulbricht, J.P. ED - Dincer, I. T1 - Bricks made of sludge from the Izmir bay - an integrative approach for the recycling of sludge - preliminary results T2 - 1st International Exergy, Energy and Environment Symposium ; IEEES-1 CY - Izmir, Turkey DA - 2003-07-13 PY - 2003 SN - 975-288440-7 SP - 995 EP - 1003 CY - Izmir AN - OPUS4-2829 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epple, Niklas A1 - Sanchez Trujillo, Camila Andrea A1 - Hau, Julia A1 - Niederleithinger, Ernst A1 - Malm, F. T1 - Structural Monitoring in an Urban Underground Metro Station Using Cod N2 - Active ultrasonic monitoring with coda wave interferometry has demonstrated its potential for structural Health monitoring in concrete structures. This study investigates its application using ultrasonic transducers embedded in the ceiling of a subway station in Munich, Germany. We evaluate the impact of environmental conditions, specifically electromagnetic interference and temperature, on data quality, as well as the influence of regular loading from passing trams. Results indicate that electromagnetic interference significantly affects measurements, while temperature effects remain minimal due to the station’s stable thermal environment. Long-term measurements and a controlled load test show that both dynamic and static loading from trams induce ultrasonic velocity changes of only 0.01%–0.06%. Although the experiment demonstrates the capacity to detect structural responses and supports the feasibility of long-term monitoring, improved electromagnetic shielding and Hardware reliability are required for successful future applications. T2 - NDT-CE 2025 CY - Izmir, Turkey DA - 24.09.2025 KW - Coda Wave Interferometry (CWI) KW - Structural health monitoring (SHM) KW - Concrete KW - Ultrasonic testing KW - Urban infrastructure PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654619 DO - https://doi.org/10.58286/31706 SN - 1435-4934 SP - 1 EP - 10 PB - e-Journal of Nondestructive Testing (eJNDT) AN - OPUS4-65461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst ED - Matsumoto, T T1 - The parallel seismic method for foundation length measurement: useful also to check pile integrity? N2 - The Parallel Seismic (PS) method is used for the determination of the unknown or undocumented depth/length of foundations, mostly piles. The method was developed some decades ago and has recently been improved by more accurate Interpretation methods. Some authors claim that the PS method might also be useful for checking the integrity of piles. The examples presented are based on rather big flaws. Numerical studies have been carried out with more realistic geometries. A finite integration technique involving cylinder symmetry (CEFIT) was used. Necks and bulges of various sizes have been simulated and the results have been compiled. It can be seen that the PS results are in fact influenced by pile irregularities. But in reality these effects are at least partly superposed by other influences or may be mistaken for effects caused by soil layering. However, the PS results and any deviation of travel time curves from a “normal” shape can be used as a hint to perform detailed studies involving other methods. T2 - 9th International conference on testing and design methods for deep foundations CY - Kanazawa, Japan DA - 18.09.2012 KW - Parallel seismic KW - Bored piles KW - Integrity KW - Low strain testing PY - 2012 SN - 978-4-89010-597-7 SP - 217 EP - 222 AN - OPUS4-27336 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Hübner, M. A1 - Müller, H. A1 - Kauther, R. T1 - Qualitätssicherung überschnittener Bohrpfahlwände mit der Ultraschallmethode am Beispiel der Schleuse Dörverden N2 - Überschnittene Bohrpfahlwände sind eine bewährte Konstruktionsmethode zur Herstellung tragender, hydraulisch dichter, tiefreichender Wände im Spezialtiefbau. Anders als bei Einzelpfählen gibt es bisher für die zerstörungsfreie Prüfung von Pfahlwänden keine etablierte Vorgehensweise. Erste Versuche an Baustellen und Modellkörpern zeigten das Potential der Ultraschallmethode (cross-hole sonic logging) zur Prüfung der Fugen über mehrere Pfähle hinweg. An der Schleusenbaustelle Dörverden ergab sich die Möglichkeit, das Verfahren unter Realbedingungen einzusetzen und die Ergebnisse visuell durch Kernbohrungen und nach Aushub zu evaluieren. Dabei wurden die meisten der prognostizierten Fehlstellen bestätigt. Die Resultate wurden in einer Neuauflage der entsprechenden Regelwerke berücksichtigt. T2 - Fachtagung Bauwerksdiagnose 2012 - Praktische Anwendungen zerstörungsfreier Prüfungen und Zukunftsaufgaben CY - Berlin, Germany DA - 23.02.2012 KW - Bohrpfahlwand KW - Ultraschallmethode PY - 2012 UR - http://www.bauwerksdiagnose2012.de/Portals/bwd2012/Dokumente/bb/v17.pdf SN - 978-3-940283-40-5 IS - Vortrag 17 SP - 1 EP - 11 CY - Berlin AN - OPUS4-27337 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Wunderlich, Carolin ED - Meßinger, J. T1 - Temperature influence on ultrasonic velocity in concrete N2 - Ultrasonic methods are valuable tools for quality assessment and structural imaging of concrete. In such applications, accurate and reliable determination of ultrasonic wave velocities is essential, as they are affected by various experimental and environmental factors. In this research coda wave interferometry (CWI) was used to determine the influence of temperature (0 to 50 °C) on ultrasonic wave velocity in concrete samples. A resolution of better than 10-4 was achieved in the measurement of relative velocity changes. Reversibility and repeatability were taken into account. In additlon the benefit of newly developed permanently embedded sensors was evaluated. The presented results can be used to Interpret and refine data from ultrasonic monitoring Systems. T2 - 2nd Neustadt workshop CY - Neustadt a.d. Weinstraße DA - 11.11.2012 KW - Coda wave interferometry KW - Concrete KW - Temperature KW - Ultrasound KW - Velocity PY - 2012 SN - 0947-1944 VL - IV SP - 60 EP - 61 PB - Dt. Geophysikalische Ges. CY - Potsdam AN - OPUS4-27224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Sabine A1 - Niederleithinger, Ernst A1 - Bohlen, T. T1 - Reverse time migration: a seismic imaging technique applied to synthetic ultrasonic data N2 - Ultrasonic echo testing is a more and more frequently used technique in civil engineering to investigate concrete building elements, to measure thickness as well as to locate and characterise built-in components or inhomogeneities. Currently the Synthetic Aperture Focusing Technique (SAFT), which is closely related to Kirchhoff migration, is used in most cases for imaging. However, this method is known to have difficulties to image steeply dipping interfaces as well as lower boundaries of tubes, voids or similar objects. We have transferred a processing technique from geophysics, the Reverse Time Migration (RTM) method, to improve the imaging of complicated geometries. By using the information from wide angle reflections as well as from multiple events there are fewer limitations compared to SAFT. As a drawback the required computing power is significantly higher compared to the techniques currently used. Synthetic experiments have been performed on polyamide and concrete specimens to show the improvements compared to SAFT. We have been able to image vertical interfaces of step-like structures as well as the lower boundaries of circular objects. It has been shown that RTM is a step forward for ultrasonic testing in civil engineering. KW - Beton KW - Ultraschall KW - Concrete KW - Imaging KW - Ultrasonics KW - Reverse time migration PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-262952 DO - https://doi.org/10.1155/2012/128465 SN - 1687-8868 SN - 1687-885X VL - 2012 IS - Article ID 128465 SP - 1 EP - 7 PB - Hindawi Publishing Corporation CY - New York, NY, USA AN - OPUS4-26295 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultrasonic methods for quality assurance and condition assessment in nuclear concrete structures – lessons learned N2 - Ultrasonic non-destructive testing methods have found various applications in quality assurance and condition assessment of nuclear concrete structures. This includes but is not limited to the localization of construction features (thickness measurements, reinforcement, tendon ducts, and others) and damage detection (e. g. corrosion or cracks). However, there are still limitations, e. g. limited penetration depth and resolution, issues when testing hybrid steel/concrete structures as well as absence of standards and regulations. This presentation will show progress in some of these issues and will focus on advanced instrumentation and validation of ultrasonic NDT for concrete structures. Ultrasonic echo testing has been limited to a penetration depth of less than one meter in reinforced concrete. The development of the LAUS (Large Aperture Ultrasonic System), using a large array of ultrasonic transducers and wider offsets between transmitter and receiver, allows to reach up to 5 m in reinforced concrete and 9 m in unreinforced concrete. This capability has been demonstrated by collecting data from an engineered salt concrete barrier in an underground nuclear waste storage facility. Due to an increasingly competitive environment, commercial manufacturers will continue to develop equipment with enhanced penetration and/or increased resolution. To quantify the capabilities and reliability of ultrasonic tests, validation mockups with engineered flaws are required. EPRI and BAM have built a large-scale mockup at a test site close to Berlin (BAM-TTS, Horstwalde) using a design which is repeated at other places. This presentation will also cover the methods deployed on engineered flaws and the repeatability of the test results. T2 - NDE in Nuclear CY - Charlotte, NC, USA DA - 25.7.2019 KW - Concrete KW - Nuclear Structures KW - Ultrasound PY - 2019 AN - OPUS4-48690 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - NDE of foundations N2 - This talk teaches the basic princioles and applications of NDT methods for deep foundations, sprecifically piles. A variety of testing methods are discussed (integrity testing, ultrasonic crosshole logging, parallel seismic and others). Capabilities and limitations are given as well as specific hints for practical use. T2 - NDE 2019 Pre-Conference Tutorial PCT 4 CY - Bangalore, India DA - 03.12.2019 KW - NDT KW - Foundation KW - Pile KW - Integrity testing PY - 2019 AN - OPUS4-50169 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Recent advances in NDE of concrete structures at BAM N2 - This talk gives an introduction to BAM and its NDT-CE division. Specific challenges in NDT-CE are discussed as well as recent research results. T2 - NDE 2019 Pre-Conference Tutorial PCT 4 CY - Bangalore, India DA - 03.12.2019 KW - NDT KW - Civil engineering PY - 2019 AN - OPUS4-50168 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 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 - 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 - Al-Neshawy, F. A1 - Ferreira, M. A1 - Bohner, E. A1 - Ojala, T. A1 - Sjöblom, V. A1 - Niederleithinger, Ernst A1 - Effner, Ute A1 - Puttonen, J. T1 - Design, Construction and NDT of a Mock-up for Reinforced Concrete Walls in NPP N2 - Construction methods, environmental stressors, and aging factors are the main causes for defects of reinforced concrete in nuclear power plants (NPP). These defects are typically occurred as corrosion of reinforcement steel, delamination, cracks, malfunction of post-tensioning or steel composite systems etc. Some of the challenges for assessing the performance of these structures by nondestructive testing methods (NDT) are that the assessment could be performed only during the annual overhauls when testing is time-limited and uncertainty of the accuracy and reliability of the available NDT testing devices combined with the lack of the international uniformity of the methods used for NDT tests. To overcome these challenges, a mock-up wall representing a section of the concrete containment of the NPP was built. The mock-up wall included simulated defects, which mimic the most common types of defects in NPP concrete structures such as dimensional errors, honeycombing, delamination, defects adjacent to the steel liner and voids in grouted tendon ducts for the post-tensioned structures. This paper introduces the design and construction of the wall including the concrete properties, reinforcement, tendon ducts and the types of the simulated defects. The paper also introduces the NDT methods and techniques that are suitable for assessing the condition of the mock-up wall under the real environmental conditions. These techniques include mechanical methods as rebound hammer, ultrasonic and electromagnetic methods. This mock-up wall will enable to investigate reliably available NDT methods and experts’ skills providing also an important and very much need educational platform for future NDE experts. T2 - SMIRT-25 CY - Charlotte, NC, USA DA - 04.08.2019 KW - NDE KW - Defects KW - Thick-walled KW - Concrete KW - Deterioration KW - Steel liner PY - 2019 SP - 1 EP - 12 AN - OPUS4-48965 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Maak, Stefan A1 - Mielentz, Frank A1 - Effner, Ute A1 - Strangfeld, Christoph A1 - Timofeev, Juri T1 - Review of recent developments in ultrasonic echo testing of concrete N2 - Ultrasonic methods are used in concrete investigations since decades. While being limited to transmission testing in the laboratory for a while, in-situ echo measurements for structural investigations and condition assessment have made their way into practical application in the past 20 years. However, several challenges remain. On one side, there are technical issues as limitations in depth of penetration, resolution and imaging capabilities. On the other side there are still gaps in validation, standardization and certification, which are limiting the applicability in condition/load capacity assessment. This review reports a couple of developments which will help to overcome these issues. This includes technical developments as new devices which are easier to handle on site or giving a much deeper penetration depth (e.g. the LAUS device at BAM) as well as improvements in imaging by hardware update (e. g. air coupled ultrasound or coded signals) or new software (e. g. RTM imaging). To foster the application in real world projects we are as well working on standardization by developing new reference specimen with international partners which will ensure world-wide comparability of ultrasonic and other methods and quality assurance codes. Further, non-destructive methods are being used to update probabilistic models used for the reassessment of existing structures to support the structural engineer’s decisions. T2 - SMAR 2019 CY - Potsdam, Germany DA - 27.08.2019 KW - Engineered Barrier System (EBS) KW - Ultraschall KW - NDT KW - Re-assessment of exiting bridges PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489686 SP - 1 EP - 6 AN - OPUS4-48968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Application of ultrasonic techniques for quality assurance of salt concrete engineered barriers: Shape, cracks and delamination N2 - The closure of underground nuclear waste disposal facilities requires reliable gas- and watertight engineered barriers. In Germany, barriers made from salt concrete have been evaluated in full scale. While the barriers seem to fulfill the requirements regarding permeability, some unexpected cracks have been detected at the surface and at depth. In cooperation between the Federal Company for Radioactive Waste Disposal (BGE) and the Federal Institute for Materials Research and Testing (BAM), several experiments have been carried out to evaluate the applicability for ultrasonic measurements in crack detection and general quality assurance. Both commercial instruments and specially developed devices have been tested on site. Using commercial ultrasonic echo devices designed for concrete inspection it was possible to detect cracks and object in salt concrete up to a depth of 2 m. The check for delamination in shotcrete is another field of application. A unique device available at BAM, the wide aperture, deep penetration instrument LAUS, was able to locate cracks and objects up to a depth of 8 m so far, which is thought to be a record for ultrasonic echo measurements in concrete. Adapted imaging procedures, partly adopted from geophysics, helped to reveal 3D structure at depth. In addition, we have developed ultrasonic probes to be deployed in boreholes, currently at up to 20 m depth. They can collect information on cracks and other features in a radius of about 1.5 m around the borehole in the current version and might be used in echo or transmission mode. Evaluation experiments have been performed at an experimental barrier at the ERAM site in Morsleben, Germany. The results showed several empty and injected cracks as well as built in instrumentation. The results have been verified using borehole endoscopy as well as core examination and will be used to set up a reliable quality assurance system for engineered barriers. All instruments are based on ultrasonic shear wave transducers with a frequency range between 25 kHz and 100 kHz. Current research focuses on the improvement of the hardware (e. g. optimization of array characteristics) and imaging techniques as Reverse Time Migration, both aiming at the improvement of depth of penetration, resolution and probability of detection. T2 - Modern 2020, 2nd International Conference about Monitoring in Geological Disposal of Radioactive Wast CY - Paris, France DA - 09.04.2019 KW - REverse Time Migration (RTM) KW - Engineered Barrier System (EBS) KW - Non-Destructive Testing KW - Ultrasonic Echo KW - Large Aperture Ultrasonic System (LAUS) KW - Synthetic Aperture Focusing Technique (SAFT) PY - 2019 AN - OPUS4-48974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Große, Christian A1 - Arndt, Ralf A1 - Mähner, Dietmar A1 - Niederleithinger, Ernst A1 - Taffe, Alexander T1 - Zerstörungsfreie Prüfung im Bauwesen: Memorandum zur Lehre an deutschsprachigen Hochschulen N2 - Dieses erste Memorandum zur Lehre und Forschung an deutschsprachigen Hochschulen auf dem Gebiet der zerstörungsfreien Prüfung im Bauwesen gibt einen Überblick hinsichtlich der akademischen Ausbildung und zeigt mögliche Schwerpunkte vor allem in der Lehre auf. Diese Schwerpunkte berücksichtigen auch aktuelle Entwicklungen und Themen auf dem Gebiet der Forschung. Es werden Anregungen zur Entwicklung bzw. Weiterentwicklung der Lehr-Curricula im Hinblick auf eine umfassende und solide fachliche Ausbildung der Studierenden des Bauwesens und angrenzender Fachrichtungen gegeben. Inhaltlich und formal lehnt sich der Beitrag an dem Memorandum der Hochschullehrer im Fachgebiet „Werkstoffe im Bauwesen“ (Breit et al., 2012) an und beruht auf einer Initiative des Unterausschusses Ausbildung – Arbeitsgruppe Ausbildung in der Hochschule – des Fachausschusses ZfP im Bauwesen der Deutschen Gesellschaft für zerstörungsfreie Prüfung (DGZfP). Die Hauptredaktion wurde übernommen von Prof. Christian U. Grosse (TU München) und Prof. Ralf W. Arndt (FH Erfurt). KW - Zerstörungsfreie Prüfung KW - Lehrplan KW - Bauwesen PY - 2019 UR - https://onlinelibrary.wiley.com/doi/epdf/10.1002/bate.201900008 DO - https://doi.org/10.1002/bate.201900008 SN - 1437-0999 SN - 0932-8351 VL - 96 IS - 4 SP - 360 EP - 368 PB - Ernst & Sohn CY - Berlin AN - OPUS4-47606 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Ertel, Jens-Peter A1 - Niederleithinger, Ernst ED - Bullock, P. ED - Verbeek, G. ED - Paikowsky, S. ED - Tara, D. T1 - Impulse Response Measurement for Pile Integrity Testing Using a Shaker as Excitation Source and Regularized Deconvolution N2 - Concrete piles are used as a foundation when the load capacity of the soil is insufficient or when the sustainable soil is found at a higher depth. Among other impact factors, the load capacity depends on the pile’s integrity and length. Therefore, verifying these parameters using adequate methods is recommended. The most common procedure is the low-strain integrity test using the hammer impact method. Developed and established in the 1970s, this method uses stress waves induced by a hammer impact at the pile head and its reflections at impedance changes (length, defects, geometry changes) to estimate the length and defect locations. Although this method is widely used due to its low cost and fast conduction in situ, one disadvantage is its inability to classify the exact type of defect, i.e., crack, change in diameter, or concrete quality. Furthermore, very long and slender piles are difficult to test and small defects cannot be detected. In addition, it is necessary for the test engineer to hold a high level of experience and expertise in this field. The European Union–funded PileInspect project (2013–2016) aimed to compensate for these disadvantages by using a low-cost shaker as the excitation source and sophisticated artificial intelligence algorithms for damage detection (higher-order spectra method). Because this technology lacks the capacity to localize damages and verify the pile length, an additional impulse response (IR) measurement technique was developed using vibrational excitation and regularized deconvolution to extract the depth information from the data in a similar manner as the hammer method. Simulations and subsequent experiments conducted at a test facility on 90-cm-diameter bored piles 11 m in length and containing cracks at approximately 4 m below the pile head confirmed the capacity to determine the pile length. Damage diagnosis and localization, however, are more difficult than for the hammer method. Although the damaged piles could be distinguished from the intact piles, in a blind test, this method might lead to misinterpretations caused by perturbations arising from the deconvolution process. The results also indicated that the low-cost shaker used for these measurements might be inappropriate for the transferal of sufficient energy. Although the IR method cannot compensate for the disadvantages of the hammer method by itself, it may enable the possibility of using long and fully controllable and repeatable signals (chirp, synthetic impacts, even noise, etc.) for pile integrity testing in the future. KW - Pile integrity testing KW - L-curve KW - Tikhonov regularization KW - NDT PY - 2019 SN - 978-0-8031-7667-6 DO - https://doi.org/10.1520/STP161120170162 VL - 1611 SP - 184 EP - 204 PB - ASTM International CY - West Conshohoken, PA, USA AN - OPUS4-48794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zheng, H. A1 - Ertel, Jens-Peter A1 - Kourmpetis, M. A1 - Kanfoud, J. A1 - Niederleithinger, Ernst A1 - Gan, T.-H. T1 - Integrity testing of cast in situ concrete piles based on an impulse response function method using sine‑sweep excitation by a shaker N2 - In this study, an Impulse Response Function analysis of pile response to sine-sweep excitation by a low cost, portable Shaker was used to identify defects in piles. In straightforward impact-echo methods, echoes from the pile toe and defects are visible in the time domain measurements. However, these echoes are not present in the time domain records of piles subjected to sine-sweep excitations, due to interactions between the input and output signals. For this reason, the impulse response function in the time domain has been calculated and is able to identify the echoes from pile impedance changes. The proposed methodology has been evaluated both numerically and experimentally. A one-dimensional pile-soil interaction system was developed, and a finite difference method used to calculate the pile response to sine-sweep excitation. The numerical simulations indicate that impulse response measurements with a synthesized logarithmic, sine-sweep excitation could be an effective tool for detecting defects in piles. The methodology was further tested with field trials on 6 cast in situ concrete test piles including 1 intact pile and 5 defective piles subjected to sine-sweep excitations by a shaker. In 5 of the 6 cases the echoes from the pile toe could be identified in the deconvoluted waveforms—the impulse Response functions. Damage detection is more difficult and dependent on the selection of the optimal regularization parameter. Further research and optimization of the deconvolution process is needed to evaluate the effectiveness compared to standard pile integrity testing methods. KW - Pile testing KW - Shaker KW - Deconvolution PY - 2019 DO - https://doi.org/10.1007/s10921-019-0595-4 SN - 0195-9298 SN - 1573-4862 VL - 38 IS - 2 SP - 55, 1 EP - 18 PB - Springer CY - Cham, Switzerland AN - OPUS4-48185 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Algernon, D. A1 - Arndt, R.W. A1 - Denzel, W. A1 - Ebsen, B. A1 - Feistkorn, S. A1 - Friese, M. A1 - Große, C.U. A1 - Kathage, S. A1 - Keßler, S. A1 - Köpp, Christian A1 - Küttenbaum, Stefan A1 - Lohse, C. A1 - Maack, Stefan A1 - Niederleithinger, Ernst A1 - Schickert, M. A1 - Schröder, G. A1 - Taffe, A. A1 - Timofeev, Juri A1 - Walther, A. A1 - Wilcke, M. A1 - Wolf, J. A1 - Wöstmann, Jens T1 - Test specimen concepts in regard to quality assurance and validation of nondestructive testing in civil engineering N2 - The process of ensuring reliability of NDT applications contains various aspects, such as determining the performance and probability of success, the uncertainty in measurement, the provision of clear and functional procedures and ensuring the correct application accordingly. Test specimens have become powerful elements in supporting many of these aspects. Within the committee for NDT in Civil Engineering (NDT-CE) of the German Society for Nondestructive Testing (DGZfP), the subcommittee on Quality Assurance (UA-QS) therefore addresses the design and the integration of test specimens in the quality assurance process. Depending on the specific purpose, the requirements on test specimens can vary significantly based on the defined simulated scenario. The most prominent purposes of test specimens might be seen in providing references for inspection systems in regard to function control, calibration and validation. Further aspects can be parametric studies, basic investigation of physical principles related to NDT or a simplified and therefore comprehensive demonstration of inspection concepts (e.g. for teaching purposes). The specific purpose of a test specimen dictates the requirements regarding its conception, including the exact design, the material or the fabrication accuracy and the conditioning. In the development of a general guideline by the UA-QS for application-specific procedures and their validation, the use of test specimens is addressed and specific concepts for the design of test specimens are made. This includes the analysis of the measurement process regarding any given application, deriving an adequate calibration approach for it and designing test specimens (calibration specimens) accordingly. Furthermore, it includes the validation of the procedure taking into account all conditions related to the specific application in the field. The validation requires a statistically sufficient number of trials. Thorough evaluation of each trial can only be established if the ground-truth is known. Therefore, test specimens providing a realistic but controlled simulation of the inspection problem are valuable and indispensable elements in the validation process. The requirement of being fully realistic will often not be possible to fulfill due to practical restrictions. Any aspect that cannot be included in the simulation realistically needs to be simulated conservatively. This again, requires a sufficient understanding of the inspection principle and technique to ensure conservativeness. Among other quality-assurance-related aspects, the UA-QS establishes concepts and guidelines regarding sound and efficient approaches for the specific purposes of test specimens. This subcommittee brings together representatives of different Groups along the entire value chain of NDT-CE, including researchers, practitioners, manufacturers and clients. They all work together in establishing a common understanding and level of quality assurance in the industry. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - Quality assurance KW - Procedure KW - Reliability KW - Validation KW - Reference specimen PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 39 EP - 48 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Algernon, D. A1 - Arndt, R.W. A1 - Denzel, W. A1 - Ebsen, B. A1 - Feistkorn, S. A1 - Friese, M. A1 - Große, C.U. A1 - Kathage, S. A1 - Keßler, S. A1 - Köpp, Christian A1 - Küttenbaum, Stefan A1 - Lohse, C. A1 - Maack, Stefan A1 - Niederleithinger, Ernst A1 - Schickert, M. A1 - Schröder, G. A1 - Taffe, A. A1 - Timofeev, Juri A1 - Walther, A. A1 - Wilcke, M. A1 - Wolf, J. A1 - Wöstmann, Jens T1 - NDT procedures in relation to quality assurance and validation of nondestructive testing in civil engineering N2 - The field of non-destructive testing of civil structures (NDT-CE) has been continuously growing. Due to the complexity and diversity of civil constructions as well as the heterogeneity of concrete, specific standards or guidelines for the application of modern NDT-CE are still missing. The development of individual solutions is the current approach, which is just as challenging as it is common for NDT-CE. With the increasing development and commercialization of NDT-CE technology, the group of practitioners is growing. To ensure a good level of quality in the industry, it appears necessary to establish adequate means. Naturally, the performance of NDT-CE methods regarding a specific application is strongly dependent on choosing the most suitable inspection technique and applying it correctly, generally referred to as the inspection procedure in the field of NDT. There are well-defined guidelines regarding procedure documentation and handling in many fields of NDT (e.g. nuclear, aerospace or automotive) according to the high importance of procedures in assuring a successful and reliable application. For a long time, this has not always been the case with NDT-CE, which is still considered a unique discipline of NDT. Part of the reason for that might be the young development state of NDTCE, the heterogeneity of building materials like concrete, timber or masonry as a material and the diversity of civil structures. In consequence, NDT-CE procedure development is considered challenging. Among other aspects, addressed in the subcommittee on Quality Assurance (UA-QS) within the committee for NDT-CE of the German Society for Nondestructive Testing (DGZfP), part of its work aims at establishing an adequate basis for NDT-CE procedure development. While some of the highly developed approaches from other industries are taken into consideration, they need to be analyzed regarding their suitability for NDT-CE and adapted accordingly. For a procedure to be as defined as possible, it needs to contain sufficient information, such as the scope and limitations regarding material, geometry and condition of the test object, inspection parameters, calibration, data acquisition, analysis criteria as well as requirements regarding the inspection personnel. For a successful implementation in the field, it is important to define the specific procedure as precisely as possible. Despite the necessity of a great amount of information to be included, the procedure needs to be suitable for efficient field application. The UA-QS is developing a guideline for NDT-CE procedures suitable for application in this field of NDT to ensure correct and reproducible application. To demonstrate and evaluate this concept, specific examples of procedures are also produced. In particular, the UA-QS has developed a procedure for the detection and positioning of tendon ducts using Ground Penetrating Radar (GPR). This procedure is tested regarding the practical applicability in a roundrobin on a defined type of reference test block. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - Quality assurance KW - Procedure KW - Reliability KW - Validation KW - Reference specimen PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 31 EP - 38 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47239 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Wiggenhauser, Herbert T1 - The LAUS: First Applications of a New System for Ultrasonic Imaging of Very Concrete Structures N2 - The LAUS (Large Aperture Ultrasonic System) has been developed to image very thick concrete structures, which are not accessible for commercial systems. The device and the corresponding software is the result of joint Research of BAM, an ultrasonic instrument manufacturer and University of Kassel, Germany. It consists of 12 separate Arrays of 32 point-contact shear wave transducers each, which can be deployed in flexible configurations. Each array is combined with battery and transmitter, receiver and wireless communication electronics. Three case histories are presented. First the system was deployed on a 5-m thick heavily reinforced foundation slab. The reflection of the slab’s bottom was imaged clearly. In addition, a multiple reflection was registered, thus giving hope that even thicker elements might be imaged by the instrument. Second, the LAUS was used to investigate a massive bridge girder where a heavy rainstorm during concreting had led to imperfections that were visible after removing the formwork was removed. The LAUS could image tendon ducts in 1.8m depth and the backwall closely behind them. Some limited areas showed blurred reflections and were checked by drill holes; these areas were affected by diffuse damage which could be repaired by injections. Third, a large retaining wall was checked for thickness. Meanwhile, the LAUS has been used in underground waste deposits (nuclear and other) for quality assurance of sealing plugs. A confirmed penetration depth of about 7 m has been reached. T2 - SMT and NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.08.2018 KW - LAUS (Large Apertur Ultrasonic System) KW - Ultrasonic echo KW - Deep penetration KW - Concrete PY - 2019 UR - https://asnt.org/smt18papers SN - 978-1-57117-456-7 VL - 11/19 SP - 208 EP - 213 PB - The American Society for Nondestructive Testing, Inc. CY - Columbus, OH, USA AN - OPUS4-47238 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 - 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 - 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 - Vössing, Konrad A1 - Gaal, Mate A1 - Niederleithinger, Ernst ED - Ross, R. ED - Sauter, U. T1 - Contactless testing of wood-based materials with novel air-coupled ultrasonic transducers N2 - The detection of delamination, rot and cracks causing a decrease of strength in wooden construction elements is a key task for nondestructive testing (NDT). Air-coupled ultrasound (ACU) is used to detect flaws without having to provide contact to the surface or otherwise affect the object. Novel ferroelectric transducers with a high signal-to-noise ratio enable an accurate flaw detection. Transducers made of cellular polypropylene (PP) are suitable for characterizing wood-based materials (WBM) because their extremely low Young’s modulus and low density mean a favorable acoustic impedance for the transmission of ultrasonic waves between the transducer and air. The transducers can be applied during the production of WBM and during its service life. The device enables a fast in-situ recognition of defects with frequencies between 90 kHz and 250 kHz. Measurements can be performed in through transmission for a high resolution or in pulse-echo technique in case of one-sided access at the expense of reduced signal strength. Ultrasonic quality assurance for wood is an important attempt to increase the acceptance of wooden structures and towards sustainability in civil engineering in general. T2 - 21. International Nondestructive Testing and evaluation of Wood Symposium CY - Freiburg, Germany DA - 24.09.2019 KW - Air-coupled ultrasound KW - Defect detection KW - Nondestructive Testing KW - Timber PY - 2019 SP - 100 PB - FVA CY - Freiburg AN - OPUS4-49169 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 - PileInspect N2 - The EC funded project PileInspect (2013-2016) has tried to improve the traditional low strain pile integrity test by using a shaker instead of a hamm and sophisticated higher order spectra analysis methods to provide automated, reliable interpretation. However, the results, even if promising, have not seen full validation yet. A second module, providing depth information by regularized deconvolution, was developed and tested successfully, but doesn't deliver additional information compared tomteh traditioanl test. T2 - DFI Seminar Pile Integrity Testing CY - Bruxelles, Belgium DA - 12.09.2019 KW - Pile integrity testing KW - Shaker KW - Higher order spectra KW - Deconvolution PY - 2019 AN - OPUS4-48948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bassil, A. A1 - Wang, Xin A1 - Chapeleau, X. A1 - Niederleithinger, Ernst A1 - Abraham, O. A1 - Leduc, D. T1 - Distributed fiber optics sensing and coda wave interferometry techniques for damage monitoring in concrete structures N2 - The assessment of Coda Wave Interferometry (CWI) and Distributed Fiber Optics Sensing (DFOS) techniques for the detection of damages in a laboratory size reinforced concrete beam is presented in this paper. The sensitivity of these two novel techniques to micro cracks is discussed and compared to standard traditional sensors. Moreover, the capacity of a DFOS technique to localize cracks and quantify crack openings is also assessed. The results show that the implementation of CWI and DFOS techniques allow the detection of early subtle changes in reinforced concrete structures until crack formation. With their ability to quantify the crack opening, following early detection and localization, DFOS techniques can achieve more effective monitoring of reinforced concrete structures. Contrary to discrete sensors, CWI and DFOS techniques cover larger areas and thus provide more efficient infrastructures asset management and maintenance operations throughout the lifetime of the structure. KW - Distributed fiber optic sensors KW - Coda wave interferometry KW - Reinforced concrete KW - Cracks KW - Damage detection KW - Structural health monitoring PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472549 DO - https://doi.org/10.3390/s19020356 SN - 1424-8220 VL - 19 IS - 2 SP - 356, 1 EP - 15 PB - MDPI AN - OPUS4-47254 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vössing, Konrad A1 - Gaal, Mate A1 - Niederleithinger, Ernst T1 - Air-coupled ferroelectret ultrasonic transducers for nondestructive testing of wood in through transmission and reflection mode N2 - The necessity and demand for nondestructive testing of wood-based materials which can automatically scan huge areas of wood is increasing. Air-coupled ultrasound (ACU) is used to detect defects and damage without altering the structure permanently. Using through transmission it is possible to detect even small holes and missing adhesive. If only one side of an object is accessible the reflection mode is preferred at the expense of a reduced resolution and penetration depth. Novel ferroelectret transducers with a high signal-to-noise ratio (SNR) enable a high-precision structure recognition. The transducers made of cellular polypropylene (PP) are quite suitable for ACU testing due to their extremely low Young’s modulus and low density which result in a favorable acoustic impedance for the transmission of ultrasonic waves between the transducer and air. Thus, defects such as delamination, rot, and cracks can be detected. Promising results were obtained under laboratory conditions with frequencies from 90 kHz to 200 kHz. The advantage of these ACU transducers is that they do not require contact to the sample, are accurate, and cost effective. Ultrasonic quality assurance for Wood is an important attempt to increase the acceptance of wooden structures and towards sustainability in civil engineering in general. T2 - International Conference on Sustainable Materials, Systems and Structures CY - Rovinj, Croatia DA - 20.03.2019 KW - Air-coupled ultrasound KW - Cellular polypropylene KW - Wood KW - Nondestructive Testing KW - Defect detection PY - 2019 SP - 28 EP - 33 AN - OPUS4-47682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -