TY - CONF A1 - Maack, Stefan A1 - Niederleithinger, Ernst T1 - Imaging of Ultrasonic Echo Measurements for Reconstruction of Technical Data of Bridges – Possibilities, Limitations and Outlook N2 - When reassessing existing concrete bridges, the challenge is often to obtain missing or incomplete information on the internal structure. In particular, the number and position of the existing reinforcement as well as the geometric dimensions of the components are of interest. Non-destructive testing methods, like radar or ultrasound, which work on the basis of the pulse-echo method, have been established for this purpose, as they only require access to the component from one side. The measurement data recorded on the structure require pre-processing to be able to reproduce the internal structure geometrically accurately. Besides different steps of data processing, the geometrical reconstruction of the measured data based on the Synthetic Aperture Focusing Technique (SAFT) is state of the art today. In this paper, the technical possibilities of the ultrasonic echo method are presented based on measurements in the laboratory and on a real bridge structure. The precision of the reconstruction and its limitations are shown. In addition to the state of the art SAFT technique, open questions and the latest research approaches, such as imaging by reverse time migration (RTM) including initial results are discussed. T2 - 13th German-Japanese Bridge Symposium CY - Osaka, Japan DA - 29.08.2023 KW - Bridge KW - Non destructive testing and evaluation KW - Concrete KW - Validation PY - 2023 SP - 1 EP - 8 AN - OPUS4-58327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maack, Stefan A1 - Niederleithinger, Ernst T1 - Imaging of Ultrasonic Echo Measurements for Reconstruction of Technical Data of Bridges – Possibilities, Limitations and Outlook N2 - When reassessing existing concrete bridges, the challenge is often to obtain missing or incomplete information on the internal structure. In particular, the number and position of the existing reinforcement as well as the geometric dimensions of the components are of interest. Non-destructive testing methods, like radar or ultrasound, which work on the basis of the pulse-echo method, have been established for this purpose, as they only require access to the component from one side. The measurement data recorded on the structure require pre-processing to be able to reproduce the internal structure geometrically accurately. Besides different steps of data processing, the geometrical reconstruction of the measured data based on the Synthetic Aperture Focusing Technique (SAFT) is state of the art today. In this paper, the technical possibilities of the ultrasonic echo method are presented based on measurements in the laboratory and on a real bridge structure. The precision of the reconstruction and its limitations are shown. In addition to the state of the art SAFT technique, open questions and the latest research approaches, such as imaging by reverse time migration (RTM) including initial results are discussed. T2 - 13th German-Japanese Bridge Symposium CY - Osaka, Japan DA - 29.08.2023 KW - Bridge KW - Non destructive testing and evaluation KW - Concrete KW - Validation PY - 2023 AN - OPUS4-58328 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Ramírez, A. A1 - Crasselt, C. A1 - Schmidt, W. A1 - Resch-Genger, Ute T1 - Utilizing optical spectroscopy and 2',7'-difluorofluorescein to characterize the early stages of cement hydration N2 - The increasingly sophisticated nature of modern, more environmentally friendly cementitious binders requires a better understanding and control particularly of the complex, dynamic processes involved in the early phase of cement hydration. In-situ monitoring of properties of a constantly changing system over a defined period of time calls for simple, sensitive, fast, and preferably also non-invasive methods like optical spectroscopy KW - Flourescence KW - Optical probe KW - Sensor KW - Dye KW - Flourescin KW - Photophysics KW - PH KW - Quantum yield KW - Quality assurance KW - Mechanism KW - Cement KW - Concrete KW - Building material KW - Hydration KW - Process monitoring PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537176 DO - https://doi.org/10.1088/2050-6120/ac2da0 SN - 2050-6120 VL - 10 IS - 1 SP - 2 EP - 13 PB - IOP Science AN - OPUS4-53717 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 - JOUR A1 - Ukrainczyk, Neven A1 - Bernard, Thomas A1 - Babaahmadi, Arezou A1 - Huang, Liming A1 - Zausinger, Christoph A1 - Soive, Anthony A1 - Bonnet, Stéphanie A1 - Georget, Fabien A1 - Mrak, Maruša A1 - Dolenec, Sabina A1 - Völker, Tobias A1 - Suraneni, Prannoy A1 - Wilson, William T1 - Test methods for chloride diffusivity of blended cement pastes: a review by RILEM TC 298-EBD N2 - The use of supplementary cementitious materials (SCM) is an important part of the roadmap for reducing CO2 emissions and extending the service life of reinforced concrete structures. To accelerate the adoption of SCMs, the RILEM Technical Committee 298-EBD evaluates scaled-down cement paste test methods to assess the effect of SCM on resistance to chloride and sulfate ingress and reactivity, which are critical to concrete durability. This review focuses on methods for measuring chloride diffusivity and is divided into four sections: diffusivity models and parameters, diffusion test methods (including NMR and chloride measurements), migration test methods and implications for future research. Key insights highlight the complexities of multi-species ionic and molecular diffusion/migration, including various binding interactions, and compares the different measurement methodologies. The review also addresses the test scale and aggregate effects, noting the pros and cons of testing at the paste, mortar, and concrete scales. The review underscores the need for further investigation into testing protocols and the influence of SCM on chloride diffusion, emphasizing that comprehensive testing across different scales provides complementary information for assessing durability performance. KW - Chloride ingress KW - Diffusion tests KW - Migration test KW - Cement paste KW - Concrete KW - Supplementary cementitious materials (SCM) PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-645889 DO - https://doi.org/10.1617/s11527-025-02809-4 SN - 1359-5997 VL - 58 IS - 10 SP - 1 EP - 35 PB - Springer Science and Business Media LLC AN - OPUS4-64588 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kruschwitz, Sabine A1 - Munsch, Sarah Mandy A1 - Telong, Melissa A1 - Schmidt, Wolfram A1 - Bintz, Thilo A1 - Fladt, Matthias A1 - Stelzner, Ludwig T1 - The NMR core analyzing TOMograph: A multi-functional tool for non-destructive testing of building materials N2 - NMR is becoming increasingly popular for the investigation of building materials as it is a non-invasive technology that does not require any sample preparation nor causes damage to the material. Depending on the specific application it can offer insights into properties like porosity and spatial saturation degree as well as pore structure. Moreover it enables the determination of moisture transport properties and the (re-)distribution of internal moisture into different reservoirs or chemical phases upon damage and curing. However, as yet most investigations were carried out using devices originally either designed for geophysical applications or the analysis of rather homogeneous small scale (< 10 mL) samples. This paper describes the capabilities of an NMR tomograph, which has been specifically optimized for the investigation of larger, heterogeneous building material samples (diameters of up to 72 mm, length of up to 700 mm) with a high flexibility due to interchangeable coils allowing for a high SNR and short echo times (50 - 80 m s). KW - Fire spalling KW - Moisture transport KW - Concrete KW - Cement hydration KW - Sensitivity KW - Supplementary cementitous materials KW - Frost salt attack PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573755 DO - https://doi.org/10.1016/j.mrl.2023.03.004 SN - 2097-0048 VL - 3 IS - 3 SP - 207 EP - 219 PB - Elsevier B.V. AN - OPUS4-57375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -