TY - CONF A1 - Niederleithinger, Ernst T1 - Seismic methods for ultrasonic testing in Civil Engineering N2 - Invited presentation on the use of seismic imaging and monitoring technologies in civil engineering T2 - Geophysikalisches Kolloquium der ETH CY - Zürich, Switzerland DA - 17.03.2017 KW - Seimic KW - Ultrasound KW - Monitoring KW - Imaging KW - Concrete PY - 2017 AN - OPUS4-39428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Krankenhagen, Rainer A1 - Weber, H. T1 - Thickness determination of semitransparent isolated solids using the flash method and an analytical model N2 - As groundwork for thickness determination of polymeric surface protection systems for concrete, we present a method for measuring the thickness of isolated semitransparent solids using pulse thermography both in Transmission and reflection geometry. Since standard models do not capture semitransparency, an advanced analytical model by Salazar et al. is applied. Physical material parameters are deduced by fitting experimental data from samples of well-known thickness. Using those, the thickness of samples of the material can be obtained by fitting, as demonstrated for different semitransparent polymer materials. T2 - QIRT 2016 CY - Gdańsk, Poland DA - 04.07.2016 KW - Analytical model KW - Concrete KW - Flash thermography KW - Semitransparency KW - Surface protection KW - Thermography KW - Thickness PY - 2016 DO - https://doi.org/10.21611/qirt.2016.001 SN - 2371-4085 VL - 2016 SP - 71 EP - 78 AN - OPUS4-37200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gottlieb, Cassian A1 - Millar, Steven A1 - Grothe, S. A1 - Wilsch, Gerd T1 - 2D evaluation of spectral LIBS data derived from heterogeneous materials using cluster algorithm N2 - Laser-induced Breakdown Spectroscopy (LIBS) is capable of providing spatially resolved element maps in regard to the chemical composition of the sample. The evaluation of heterogeneous materials is often a challenging task, especially in the case of phase boundaries. In order to determine information about a certain phase of a material, the need for a method that offers an objective evaluation is necessary. This paper will introduce a cluster algorithm in the case of heterogeneous building materials (concrete) to separate the spectral information of non-relevant aggregates and cement matrix. In civil engineering, the information about the quantitative ingress of harmful species like Cl−, Na+ and SO2−4 is of great interest in the evaluation of the remaining lifetime of structures (Millar et al., 2015; Wilsch et al., 2005). These species trigger different damage processes such as the alkali-silica reaction (ASR) or the chloride-induced corrosion of the reinforcement. Therefore, a discrimination between the different phases, mainly cement matrix and aggregates, is highly important (Weritz et al., 2006). For the 2D evaluation, the expectation-maximizationalgorithm (EM algorithm; Ester and Sander, 2000) has been tested for the application presented in this work. The method has been introduced and different figures of merit have been presented according to recommendations given in Haddad et al. (2014). Advantages of this method will be highlighted. After phase separation, non-relevant information can be excluded and only the wanted phase displayed. Using a set of samples with known and unknown composition, the EM-clustering method has been validated regarding to Gustavo González and Ángeles Herrador (2007). KW - LIBS KW - Concrete KW - EM-clustering KW - Heterogeneity PY - 2017 DO - https://doi.org/10.1016/j.sab.2017.06.005 SN - 0584-8547 VL - 2017 IS - 134 SP - 58 EP - 68 PB - Elsevier B.V. AN - OPUS4-40644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gottlieb, Cassian T1 - Material properties and their impact on laserinduced plasmas for concrete analysis N2 - For concrete production aggregates, cement and water are mixed together and after 28 days of hydration a porous and multiphase material is formed. To consider the heterogeneity of concrete a 2D scanning system is used. The coarse aggregates (limit > 2 X d ) can be excluded. laser spot The remaining content is a mixture of flour grains and cement particles (micro heterogeneity). Harmful species like chlorides may penetrate together with water through the capillary pore space. A quantification of Cl regarding to the cement content only (European standard EN 206) is necessary for the damage assessment. A LIBS system operating with a NdCr:YAG laser (pulse energy of 3 mJ, a wavelength of 1064 nm, a pulse width of 1.5 ns, a repetition rate of 100 Hz) and two Czerny-Turner spectrometer (UV and NIR range) have been used. T2 - EMSLIBS Konferenz 2017 CY - Pisa, Italy DA - 12.06.2017 KW - Concrete KW - LIBS KW - Micro-heterogeneity PY - 2017 AN - OPUS4-40938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gottlieb, Cassian T1 - Influence of grain sizes on the quantification of libs measurements in concrete influence of grain sizes on the quantification of libs measurements in concrete N2 - Concrete is a multiphase material made of cement, aggregates and water. The heterogeneity of concrete is a result of mixing aggregates (grain size between 0.125 mm to 32 mm) and cement (grain size < 0.04 mm) together. There are always aggregates with a grain size below 0.125 mm (flour grains) therefore the cement matrix is always a mixture of these small particles. Different grain size distributions by making concrete are important to ensure the needed density and com-pressive strength. In order to estimate the remaining lifetime of concrete structures the quantification of element concentra-tions of alkali and chlorides regarding to the cement matrix only (1/3 of the total mass), is a major concern in civil engineer-ing. Due to two-dimensional scanning with LIBS the coarse aggregates can be evaluated and excluded from the analysis. In the case of particles (flour grains and cement) smaller than the laser spot size, the microscopic hetero-geneity influences the laser-plasma interaction and has therefore an impact on the results. In this study the influence of the micro-heterogeneity and the impact on the laser-material interaction is examined. The effect of changing ratios between cement particles and aggregate particles in the laser-induced plasma has been analyzed (see figure 1, right). Therefore, different samples with defined grain sizes are prepared and the obtained distributions were analyzed with x-ray diffraction (XRD). For the LIBS measurements, an automated system that operates with a low energy NdCr:YAG laser (pulse energy of 3 mJ, a wavelength of 1064 nm, a pulse width of 1.5 ns, a repetition rate of 100 Hz) and a NIR Czerny-Turner spectrometer has been used. T2 - EMSLIBS Konferenz 2017 CY - Pisa, Italy DA - 12.06.2017 KW - Grain size KW - LIBS KW - Concrete PY - 2017 AN - OPUS4-40940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Priebe, Nsesheye Susan T1 - A modified cementitious system for sub-Saharan Africa N2 - Supplementary cementitious materials (SCMs) are largely used all over the world. The leading SCMs are fly ash (FA) and slag. However, such materials originate from industries that are not well established in sub-Saharan Africa (SSA). Therefore, it becomes extremely challenging and expensive to build up sustainable cement and concrete. For SSA, agriculture is one of the leading economic sectors. Agricultural by-products such as rice husk ash (RHA), can be a potential binder material beneficial for use in a cementitious system. RHA combined with limestone filler (LSF) is an option that can be practised for rice producing countries in Africa. T2 - PhD Day CY - Berlin, Germany DA - 14.07.2015 KW - Supplementary cementitious materials KW - Rice husk as KW - Cement KW - Concrete KW - Sustainable PY - 2015 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-41029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF ED - Voigt, Gerrit T1 - Determining moisture in materials and IoT N2 - Knowing the state of the setting process of concrete in buildings or the moisture level of old walls can be crucial in determining further steps in the construction or restoration process. Small 2.4 GHz modules can be either embedded or applied on the surface to determine the moisture distribution in material. Common modules, that are based on the highly available Bluetooth Low Energy standard, emit electromagnetic waves, whose signal strength gets dampened by water molecules. This effect serves as the basis on determining the moisture level in material. We will show how to apply this method in a meshed sensor network for online monitoring. T2 - SMAR2017 CY - Zurich, Switzerland DA - 13.09.2017 KW - Moisture KW - Concrete KW - Radio signals KW - Bluetooth PY - 2017 SP - Paper 152, 1 EP - 6 CY - Zürich, Switzerland AN - OPUS4-41997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Voigt, Gerrit T1 - Determining moisture in materials and IoT N2 - Knowing the state of the setting process of concrete in buildings or the moisture level of old walls can be crucial in determining further steps in the construction or restoration process. Small 2.4 GHz modules can be either embedded or applied on the surface to determine the moisture distribution in material. Common modules, that are based on the highly available Bluetooth Low Energy standard, emit electromagnetic waves, whose signal strength gets dampened by water molecules. This effect serves as the basis on determining the moisture level in material. We will show how to apply this method in a meshed sensor network for online monitoring. T2 - Fourth Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures CY - Zurich, Switzerland DA - 13.09.2017 KW - Moisture KW - Concrete KW - Radio signals KW - Bluetooth PY - 2017 AN - OPUS4-41999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Colla, Camilla A1 - Krause, Martin A1 - Maierhofer, Christiane A1 - Höhberger, H.-J. A1 - Sommer, H. T1 - Combination of NDT techniques for site investigation of non-ballasted railway tracks N2 - Today's civil engineering NDT needs are for quantitative, fast to apply and easy to interpret methods. They are required on site both for evaluation of existing structures/infrastructure and for quality control in new construction. With this purpose, BAM has carried out in-situ feasibility studies, using radar, impact-echo and ultrasonic-echo methods. Two examples are given of their combined application on different railway slab–track constructions, using high frequency radar, scanning impact-echo and ultrasonic array methods. The aim was to evaluate limitations and advantages, comparability and complementarity of these methods. The on-site measurements demonstrated the possibility to investigate, with good accuracy via NDT, the bonding conditions between sleepers and slab, to locate voids and measure layer thickness. The acoustic and electromagnetic methods used, were found to be complementary. KW - Concrete KW - NDT KW - Impact echo KW - Ultrasonics KW - Radar KW - Railway PY - 2002 DO - https://doi.org/10.1016/S0963-8695(01)00033-0 SN - 0963-8695 VL - 35 SP - 95 EP - 105 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-1858 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Moisture testing and mapping N2 - Non-destructive testing of moisture in building materials T2 - NDT&E Advanced Training Workshop CY - Berlin, Germany DA - 27.06.2018 KW - Building materials KW - Concrete KW - Moisture measurement PY - 2018 AN - OPUS4-45348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Moisture testing and mapping N2 - Discussion and presentation of different methods for moisture measurements in civil Engineering. T2 - NDT&E Advanced Training Workshop CY - Berlin, Germany DA - 05.07.2017 KW - Moisture measurement KW - Building materials KW - Concrete PY - 2017 AN - OPUS4-42623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Validierung und Vergleich verschiedener Methoden zur Bestimmung von Flüssigwasser in Baustoffen N2 - Darstellung der aktuellen Feuchtemesstechnik im Bauwesen. Erklärung der Grundlagen über die Sorptionsisotherme und den Wasserdampfpartialdruck. Vorstellung der Ergebnisse der korrespondierenden relativen Luftfeuchtemessungen. T2 - Abteilungsseminar der Abteilung 8, BAM CY - BAM, Berlin, Germany DA - 06.11.2017 KW - Concrete KW - Material moisture KW - Moisture measurements KW - Moisture in civil engineering KW - Corresponding relative humidity PY - 2017 AN - OPUS4-42744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - RFID based sensors in civil engineering N2 - Damages in infrastructure due to moisture amount to billions of Euros every year. For a more predictive structural health monitoring in civil engineering, the detection and monitoring of hazardous moisture in steel reinforced concrete constructions is of high interest. The sensors have to be wireless, elsewise they weaken the concrete cover of the rebars. The lifetime of such constructions is normally decades, thus the sensors have to be battery-free and fully passive. Considering these requirements, passive RFID-based sensors are developed. Communication and energy supply are realized wireless via the electromagnetic field of a RFID transmitter. The passive RFID based sensors are embedded into the concrete to enable the monitoring of moisture transport in porous materials. Results of the hydration process are shown. T2 - RFID tomorrow & wireless IoT CY - Düsseldorf, Germany DA - 27.09.2017 KW - RFID based sensors KW - Moisture monitoring KW - Concrete KW - Embedded sensors PY - 2017 AN - OPUS4-42622 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Moisture testing and mapping N2 - Discussion and presentation of different methods for moisture measurements in civil engineering. T2 - NDT&E Advanced Training Workshop CY - Berlin, Germany DA - 05.07.2017 KW - Building materials KW - Moisture measurements KW - Concrete PY - 2017 SP - 87 EP - 107 CY - Berlin, Germany AN - OPUS4-42624 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Küttenbaum, Stefan T1 - Reliability assessment of existing bridges based on NDT-results N2 - The non-destructive testing methods available for civil engineering (NDT-CE) enable the measurements of quantitative parameters, which realistically describe the characteristics of existing buildings. In the past, methods for quality evaluation and concepts for validation expanded into NDT-CE to improve the objectivity of measured data. Thereby, a metrological foundation was developed to collect statistically sound and structurally relevant information about the inner construction of structures without destructive interventions. More recently, the demand for recalculations of structural safety was identified. This paper summarizes a basic research study on structural analyses of bridges in combination with NDT. The aim is to use measurement data of nondestructive testing methods as stochastic quantities in static calculations. Therefore, a methodical interface between the guide to the expression of uncertainty in measurement and probabilistic approximation procedures (e.g. FORM) has been proven to be suitable. The motivation is to relate the scientific approach of the structural analysis with real information coming from existing structures and not with those found in the literature. A case study about the probabilistic bending proof of a reinforced concrete bridge with statistically verified data from ultrasonic measurements shows that the measuring results fulfil the requirements concerning precision, trueness, objectivity and reliability. T2 - 5th ICCRRR 2018 - International Conference on Concrete Repair, Rehabilitation and Retrofitting CY - Cape Town, South Africa DA - 19.11.2018 KW - NDT KW - Concrete KW - Stochastic model KW - Reassessment KW - Reliability PY - 2018 AN - OPUS4-46768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Küttenbaum, Stefan A1 - Braml, T. A1 - Taffe, A. A1 - Maack, Stefan ED - Pellegrino, C. ED - Faleschini, F. ED - Zanini, M.A. ED - Matos, J.C. ED - Casas, J.R. ED - Strauss, A. T1 - From Uncertainty in Measurement to Certainty in Bridge Reassessment N2 - "The reassessment of bridges continues to take great importance both nationally and internationally. A major challenge is to find computation models reflecting the actual properties of the considered structures sufficiently accurate. Besides regular inspections, the conduction of advanced measurements is suitable to generate reliable information about a structure to be assessed. Prior to incorporating measurement results in reassessment, the relevance, the trueness, and the precision of the measured information needs to be stated. On the one hand, the use of information whose quality has not been assessed can lead to errors with serious consequences. On the other, the measurement of irrelevant information is inefficient. Although the use of measured data in assessment is currently mostly unregulated, their appreciation in reliability analyses is beneficial since the built environment can be assessed more realistically. Utilizing NDT in reassessment has the potential to extend remaining lifetimes of a structure, save resources, and improve infrastructural availabilities. The power of judgment regarding the decision on the reliability of an existing structure can be increased. In this contribution, an approach is outlined to process non-destructively gathered measurement data in a comparableway in order to include themeasured information in probabilistic reliability assessments of existing structures. An essential part is the calculation of measurement uncertainties. The effect of incorporating evaluated NDT-results is demonstrated by means of a prestressed concrete bridge and GPR measurements conducted on this bridge as a case-study. The bridge is assessed regarding SLS Decompression using the NDT-results." KW - Reliability KW - Assessment KW - Existing structures KW - NDT KW - Concrete PY - 2022 DO - https://doi.org/10.1007/978-3-030-91877-4_58 VL - 200 SP - 509 EP - 517 PB - Springer CY - Cham AN - OPUS4-54019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - TC 286-GDP STAR - chapter: Modelling moisture transport in porous media N2 - The current content and structure of the chapter "Modelling moisture transport in porous media" of the state of the art report is presented. T2 - RILEM Spring Convention 2021 CY - Online meeting DA - 06.04.2021 KW - Moisture transport KW - Porous media KW - Modelling mass transfer KW - Gas diffusion KW - Concrete PY - 2021 AN - OPUS4-52405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Küttenbaum, Stefan T1 - From uncertainty in measurement to certainty in bridge assessment N2 - In this contribution, an approach is outlined to process non-destructively gath-ered measurement data in a comparable way in order to include the measured information in probabilistic reliability assessments of existing structures. An es-sential part is the calculation of measurement uncertainties. The effect of incor-porating evaluated NDT-results is demonstrated by means of a prestressed con-crete bridge and GPR measurements conducted on this bridge as a case-study. The bridge is assessed regarding SLS Decompression using the NDT-results. T2 - 1st Conference of the European Association on Quality Control of Bridges and Structures – EUROSTRUCT2021 CY - Padova, Italy DA - 29.08.2021 KW - Reliability KW - Assessment KW - Existing structures KW - NDT KW - Concrete PY - 2021 AN - OPUS4-53173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diewald, F. A1 - Epple, Niklas A1 - Kraenkel, T. A1 - Gehlen, C. A1 - Niederleithinger, Ernst T1 - Impact of External Mechanical Loads on Coda Waves in Concrete N2 - During their life span, concrete structures interact with many kinds of external mechanical loads. Most of these loads are considered in advance and result in reversible deformations. Nevertheless, some of the loads cause irreversible, sometimes unnoticed changes below the macroscopic scale depending on the type and dimension of the impact. As the functionality of concrete structures is often relevant to safety and society, their condition must be known and, therefore, assessed on a regular basis. Out of the spectrum of non-destructive monitoring methods, Coda Wave Interferometry using embedded ultrasonic sensors is one particularly sensitive technique to evaluate changes to heterogeneous media. However, there are various influences on Coda waves in concrete, and the interpretation of their superimposed effect is ambiguous. In this study, we quantify the relations of uniaxial compression and uniaxial tension on Coda waves propagating in normal concrete. We found that both the signal correlation of ultrasonic signals as well as their velocity variation directly reflect the stress change in concrete structures in a laboratory environment. For the linear elastic range up to 30% of the strength, we calculated a velocity variation of −0.97‰/MPa for compression and 0.33%/MPa for tension using linear regression. In addition, these parameters revealed even weak irreversible changes after removal of the load. Furthermore, we show the time-dependent effects of shrinkage and creep on Coda waves by providing the development of the signal parameters over time during half a year together with creep recovery. Our observations showed that time-dependent material changes must be taken into account for any comparison of ultrasonic signals that are far apart in time. The study’s results demonstrate how Coda Wave Interferometry is capable of monitoring stress changes and detecting even small-size microstructural changes. By indicating the stated relations and their separation from further impacts, e.g., temperature and moisture, we anticipate our study to contribute to the qualification of Coda Wave Interferometry for its application as an early-warning system for concrete structures. KW - Ultrasound KW - Coda Wave Interferometry (CWI) KW - Mechanical Load KW - Microstructure KW - Concrete PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556878 DO - https://doi.org/10.3390/ma15165482 SN - 1996-1944 VL - 15 IS - 16 SP - 1 EP - 15 PB - MDPI AN - OPUS4-55687 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maack, Stefan A1 - Küttenbaum, Stefan A1 - Niederleithinger, Ernst T1 - Practical procedure for the precise measurement of geometrical tendon positions in concrete with ultrasonic echo N2 - Existing concrete structures were usually designed for lifetimes of several decades. The current and urgently required efforts to increase sustainability and protect the environment will likely result in extended service lives up to 100 years. To achieve such objectives, it is required to assess structures over their entire lifecycles. Non-destructive testing (NDT) methods can reliably support the assessment of existing structures during the construction, operational, and decommissioning phases. One of the most important and safety-relevant components of a prestressed concrete structure are the tendons. NDT methods such as the ultrasonic echo method are suitable for both the detection and the localization of the tendons, i.e., the measurement of their geometrical position inside the component. The uniqueness of structures, concrete heterogeneity, and varying amounts of secondary components such as the reinforcement represent obstacles in the application of these methods in practice. The aim of this contribution is to demonstrate a practicable procedure, that can be used in the field to determine the parameters required for the measuring data analysis without extensive knowledge about the investigated components. For this purpose, a polyamide reference specimen is used to show which steps are required to obtain reliable imaging information on the position of tendons from the measurement data. The procedure is then demonstrated on a concrete test specimen that covers various relevant and practice-oriented test scenarios, such as varying tendon depths and component thicknesses. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2022) CY - Cape Town, South Africa DA - 03.10.2022 KW - Validation KW - Non-destructive testing KW - Ultrasonic KW - Reconstruction KW - Concrete KW - Tendon duct PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559979 DO - https://doi.org/10.1051/matecconf/202236403007 SN - 2261-263X SP - 1 EP - 8 AN - OPUS4-55997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Wang, Xin A1 - Herbrand, M. A1 - Müller, M. T1 - Processing ultrasonic data by coda wave interferometry to monitor load tests of concrete beams N2 - Ultrasonic transmission measurements have been used for decades to monitor concrete elements, mostly on a laboratory scale. Recently, coda wave interferometry (CWI), a technique adapted from seismology, was introduced to civil engineering experiments. It can be used to reveal subtle changes in concrete laboratory samples and even large structural elements without having a transducer directly at the place where the change is taking place. Here, several load tests until failure on large posttensioned concrete beams have been monitored using networks of embedded transducers. To detect subtle effects at the beginning of the experiments and cope with severe changes due to cracking close to failure, the coda wave interferometry procedures had to be modified to an adapted step-wise approach. Using this methodology, we were able to monitor stress distribution and localize large cracks by a relatively simple technique. Implementation of this approach on selected real structures might help to make decisions in infrastructure asset management. KW - Ultrasound KW - Concrete KW - Monitoring KW - Coda wave interferometry KW - Embedded transducers PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-452328 DO - https://doi.org/10.3390/s19010147 SN - 1424-8220 VL - 19 IS - 1 SP - Article 147, 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-45232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Coelho Lima, Isabela A1 - Grohmann, Maria A1 - Niederleithinger, Ernst T1 - Advanced ultrasonic imaging for concrete: Alternative imaging conditions for reverse time migration N2 - Ultrasound echo is a widely used NDT technique for determining the internal geometry of structures. Reverse-time migration (RTM) has been recently introduced to NDT applications, as an imaging method for ultrasound data, to overcome some of the limitations (e.g. imaging steeply dipping reflector) experienced by the Synthetic Aperture Focusing Technique (SAFT), the most commonly used imaging algorithm for these measurements. The standard implementation of RTM also experiences some drawbacks caused by its imaging condition, which is based on the zero-lag of the cross-correlation between source and receiver wavefields and generates high-amplitude low-frequency artifacts. Three alternative imaging conditions, developed for seismic data applications, were tested for their ability to provide better images than the standard cross-correlation: illumination compensation, deconvolution and wavefield decomposition. A polyamide specimen was chosen for the simulation of a synthetic experiment and for real data acquisition. The migrations of both synthetic and real data were performed with the software Madagascar. The illumination imaging condition was able to reduce the low-frequency noise and had a good performance in terms of computing time. The deconvolution improved the resolution in the synthetic tests, but did not showed such benefit for the real experiments. Finally, as for the wavefield decomposition, although it presented some advantages in terms of attenuating the low-frequency noise and some unwanted reflections, it was not able to image the internal structure of the polyamide as well as the cross-correlation did. Suggestions on how to improve the cost-effectiveness of the implementation of the deconvolution and wavefield decomposition were presented, as well as possible investigations that could be carried out in the future, in order to obtain better results with those two imaging conditions. T2 - DGZfP Jahrestagung 2018 CY - Leipzig DA - 07.05.2018 KW - Ultrasound KW - Reverse time migration KW - Imaging condition KW - Concrete PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-448704 SP - Mi.3.A.4, 1 EP - 10 PB - DGZfP AN - OPUS4-44870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abraham, O. A1 - Ferria, H. A1 - Niederleithinger, Ernst A1 - Brühwiler, E. A1 - Dalsgard Sörensen, J. A1 - Klikowicz, P. A1 - Kirsch, F. A1 - Niedermayer, H. A1 - Yalamas, T. T1 - INFRASTAR - Innovation and networking for fatigue and reliability analysis of structures - Training for assessment of risk - H2020 N2 - "INFRASTAR aims to develop knowledge, expertise and skills for optimal and reliable management of structures. The generic methodology is applied to bridges and wind turbines in relation to fatigue offering the opportunity to deal with complementary notions (such as old and new asset management, unique and similar structures, wind and traffic actions) while addressing 3 major challenges: 1/ advanced modelling of concrete fatigue behaviour, 2/new non destructive testing methods for early aged damage detection and 3/probabilistic approach of structure reliability under fatigue. Benefit of cross-experience and inter-disciplinary synergies creates new knowledge. INFRASTAR proposes innovative solutions for civil infrastructure asset management so that young scientists acquire a high employment profile in close dialogue between industry and academic partners. Modern engineering methods, including probabilistic approaches, risk and reliability assessment tools, will take into account the effective structural behaviour of existing bridges and wind turbines by exploiting monitored data. Existing methods and current state-of -the art is based on excessive conservatism which produces high costs and hinders sustainability. INFRASTAR improves knowledge for optimising the design of new structures, for more realistic verification of structural safety and more accurate prediction of future lifetime of the existing structures. That is a challenge for a sustainable development because it reduces building material and energy consumption as well as CO2 production. Within the global framework of optimal infrastructure asset management, INFRASTAR will result in a multi-disciplinary body of knowledge covering generic problems from the design stage process of the new civil infrastructures up to recycling after dismantlement. This approach and the proposed methods and tools are new and allow a step forward for innovative and effective process." KW - Concrete KW - Fatigue KW - Wind turbine KW - Bridge PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-447016 UR - http://www.ingentaconnect.com/content/sil/impact/2018/00002018/00000001/art00023 DO - https://doi.org/10.21820/23987073.2018.70 SN - 2398-7073 VL - 2018 IS - 1 SP - 70 EP - 72 PB - Science Impact Ltd. CY - Bristol, UK AN - OPUS4-44701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Wang, Xin A1 - Mierschke, Vivien A1 - Bertschat, Anja Sophie T1 - Concepts from seismic interferometry transferred to sonic and ultrasonic concrete inspection and monitoring N2 - Seismic interferometry (SI) deals either with the sensible detection of changes in the subsurface or with the reconstruction of virtual signals between two receivers by crosscorrelation of signals from diffuse sources. These concepts can be applied in NDT in civil engineering for various purposes, e. g. to detect changes in bridges. Here it is demonstrated using data from a reference structure on our test site. Practical applications can be expected in the very near future. T2 - 12th European Conference on Non-Destructive Testing (ECNDT 2018) CY - Gothenburg, Sweden DA - 11.6.2018 KW - Ultrasound KW - Concrete KW - Monitoring KW - Coda KW - Interferometry PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-468465 UR - http://www.ndt.net/?id=22760 SN - 1435-4934 VL - 23 IS - 8 SP - 1 EP - 2 PB - NDT.net CY - Kirchwald AN - OPUS4-46846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Gardner, S. A1 - Kind, Thomas A1 - Kaiser, R. A1 - Grunwald, Marcel A1 - Yang, G. A1 - Redmer, Bernhard A1 - Waske, Anja A1 - Mielentz, Frank A1 - Effner, Ute A1 - Köpp, Christian A1 - Clarkson, A. A1 - Thompson, F. A1 - Ryan, M. A1 - Mahon, D. T1 - Muon Tomography of the Interior of a Reinforced Concrete Block: First Experimental Proof of Concept N2 - Quality assurance and condition assessment of concrete structures is an important topic world-wide due to the aging infrastructure and increasing traffic demands. Common topics include, but are not limited to, localisation of rebar or tendon ducts, geometrical irregularities, cracks, voids, honeycombing or other flaws. 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. Until the 1980s X-ray transmission was used 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. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened up new fields of application, such as the investigation of freight containers. Muon imaging also has the potential to fill some of the gaps currently existing in concrete NDT. As a first step towards practical use 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 are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. The data acquisition takes more time and signals contain more noise, but the images allowed to detect the same important features that are visible in conventional high energy X-ray tomography. In our experiment, we have shown that muon imaging has potential for concrete inspection. The next steps include the development of mobile detectors and optimising acquisition and imaging parameters. KW - Concrete KW - Muon KW - Radar KW - Ultrasound KW - X-ray PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-529974 DO - https://doi.org/10.1007/s10921-021-00797-3 VL - 40 IS - 3 SP - 1 EP - 14 PB - Springer Nature AN - OPUS4-52997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, U. A1 - Pudovikov, S. A1 - Herrmann, H.-G. A1 - Wiggenhauser, H. A1 - Prabhakara, Prathik A1 - Niederleithinger, Ernst T1 - Evaluation of retroreflective corner echo for detection of surface breaking cracks in concrete by ultrasound N2 - The retroreflective corner echo is used, for example, in ultrasonic non-destructive testing of metals to find fatigue cracks in tubes or shafts. If the much weaker crack tip signal is additionally detected, the crack length can also be determined. A corner reflection occurs in cases of surface breaking cracks with predominantly perpendicular orientation to the surface. The intensity of the corner reflection depends on the angle of incidence and on the ultrasonic wave mode used. For the reliable detection of vertical surface breaking cracks in metals, transversal waves are commonly used, which propagate at an angle of 37° to 53° to the inspection surface. As shown in this contribution, the wide spread low frequency ultrasonic arrays with dry point contact sources available for ultrasonic testing of concrete also allow to receive corner echoes. These devices generate transversal waves in concrete structures with a large divergence of the sound field. A series of experiments was carried out with such dry point contact arrays on concrete specimens with artificial test defects and controlled induced cracks of different depths. The ultrasonic time-of-flight signals were recorded, exported and reconstructed utilising the SAFT (Synthetic Aperture Focusing Technique) algorithm. The SAFT reconstruction parameters were adjusted to visualize the corner echo indication. As will be shown, with this targeted processing, the reproducible detection of surface breaking cracks in concrete is possible. The retroreflective corner echo can thus be exploited in civil engineering for non-destructive inspection of concrete. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Concrete KW - Crack depth KW - Ultrasound KW - SAFT PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563365 UR - https://www.ndt.net/article/ndtce2022/paper/27256_manuscript.pdf IS - 27256 SP - 1 EP - 4 PB - NDT.net AN - OPUS4-56336 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Landis, E. A1 - Hassefras, Emiel A1 - Oesch, Tyler A1 - Niederleithinger, Ernst T1 - A Microstructural Basis for Diffuse Ultrasound in Concrete N2 - Attenuation of ultrasonic signals in concrete has the potential to carry much information about the microstructure of the material. In this work a series of concrete specimens of varying porosities and pore size distributions were internally imaged with x-ray computed tomography (CT), and then subsequently examined with throughtransmission ultrasound. The CT images were used to quantify both capillary porosity of cement paste as well as internal interfaces that are likely to produce elastic wave scattering. Ultrasound signals were represented as a diffusion process such that absorption and scattering attenuation could be isolated. As implemented, the diffusion model was a poor predictor of capillary porosity, while diffusivity was a reasonable predictor of scattering interfaces. Diffusivity was found to scale extremely well with small scale porosity, which made it a good predictor of compressive strength. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Concrete KW - X-ray tomography KW - Ultrasound PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563371 UR - https://www.ndt.net/article/ndtce2022/paper/61592_manuscript.pdf SP - 1 EP - 4 PB - NDT.net AN - OPUS4-56337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grohmann, Maria A1 - Niederleithinger, Ernst A1 - Buske, S. A1 - Büttner, C. T1 - Application of Elastic P-SV Reverse Time Migration to Synthetic Ultrasonic Echo Data from Concrete Members N2 - The ultrasonic echo technique is frequently used in non-destructive testing (NDT) of concrete structures for thickness measurements, geometry determinations as well as localization of built-in components. To improve ultrasonic imaging of complex structures in concrete, we transferred a geophysical imaging technique, the reverse time migration (RTM), to NDT in civil engineering. In contrast to the conventionally used synthetic aperture focusing technique (SAFT) algorithms, RTM is a wavefield continuation method in time and uses the full wave equation. Thus, RTM can handle complicated wave propagations in any direction without dip limitation. In this paper, we focused on the application and evaluation of a two-dimensional (2D) elastic RTM algorithm considering compressional waves, vertically polarized shear waves, and Rayleigh waves. We tested the elastic RTM routine on synthetic ultrasonic echo data generated with a 2D concrete model consisting of several steps and circular air inclusions. As these complex structures can often be found in real-world NDT use cases, their imaging is especially important. By using elastic RTM, we were able to clearly reproduce vertical reflectors and lower edges of circular air voids inside our numerical concrete model. Such structures cannot be imaged with conventional SAFT algorithms. Furthermore, the used elastic RTM approach also yielded a better reconstruction of a horizontal reflector and upper boundaries of circular air inclusions. Our encouraging results demonstrate that elastic RTM has the potential to significantly improve the imaging of complex concrete structures and, thus, is a step forward for detailed, high-quality ultrasonic NDT in civil engineering. KW - Concrete KW - Ultrasound KW - Imaging KW - Reverse time migration KW - Elastic PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580680 DO - https://doi.org/10.1007/s10921-023-00962-w SN - 0195-9298 VL - 42 IS - 3 SP - 1 EP - 18 PB - Springer Nature AN - OPUS4-58068 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabe, U. A1 - Pudovikov, S. A1 - Herrmann, H.-G. A1 - Wiggenhauser, H. A1 - Prabhakara, Prathik A1 - Niederleithinger, Ernst T1 - Using the Corner Reflection for Depth Evaluation of Surface Breaking Cracks in Concrete by Ultrasound N2 - The corner echo is a well-known effect in ultrasonic testing, which allows detection of surface breaking cracks with predominantly perpendicular orientation to the surface as, for example, corrosion cracks in metal pipes or shafts. This echo is formed by two planes, the surface of the crack and the surface which the crack breaks. It can also be classified as a half-skip method, since a reflection of the pulse occurs on the backwall before the reflection at the defect takes place. In combination with the diffraction from the crack tip, the corner echo also allows crack sizing. As shown in this paper, the corner reflection can be used in civil engineering for nondestructive inspection of concrete. Commercially available low frequency ultrasonic arrays with dry point contact sources generate SH transversal waves with sufficient divergence of the sound field in order to detect corner reflections. Ultrasonic line-scans and area-scans were acquired with a linear array on flat concrete specimens, and the data were reconstructed by the Synthetic aperture focusing technique. If the angles and the area of reconstruction are chosen accordingly, the corner echo reflection can be distinguished from other ultrasonic information. The corner echo can thus be used as a method for deciding whether a crack is a partial-depth crack or a full-depth crack and thus for obtaining a statement about crack depth. This paper presents corresponding experimental results obtained on concrete specimens with artificial test defects and cracks induced under controlled conditions. KW - Ultrasound KW - Crack depth KW - Concrete KW - Corner echo PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574631 DO - https://doi.org/10.1007/s10921-023-00956-8 SN - 0195-9298 VL - 42 IS - 2 SP - 1 EP - 19 PB - Springer Nature AN - OPUS4-57463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Guangliang, Y. A1 - Mahon, D. A1 - Gardner, S. T1 - Muon tomography applied to assessment of concrete structures: First experiments and simulations. N2 - Non-destructive techniques for reinforced or prestressed concrete inspection 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. Until the 1980s X-ray transmission was used 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. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened new fields of application. 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 are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. In a second step, we have performed simulations to assess the potential for a set of important testing problems such as grouting defects in tendon ducts. The next steps include the development of mobile detectors and optimizing acquisition and imaging parameters. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Muon tomography KW - Concrete KW - Inspection KW - Simulation PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563224 UR - https://www.ndt.net/article/ndtce2022/paper/60943_manuscript.pdf SP - 1 EP - 8 PB - NDT.net AN - OPUS4-56322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prabhakara, Prathik A1 - Mielentz, Frank A1 - Stolpe, Heiko A1 - Behrens, Matthias A1 - Lay, Vera A1 - Niederleithinger, Ernst T1 - Validation of novel ultrasonic phased array borehole probe by using simulation and measurement N2 - Low-frequency ultrasonic testing is a well-established non-destructive testing (NDT) method in civil engineering for material characterization and the localization of cracks, reinforcing bars and delamination. A novel ultrasonic borehole probe is developed for in situ quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The aim is to examine the sealing structures made of salt concrete for any possible cracks and delamination and to localize built-in components. A prototype has been developed using 12 individual horizontal dry point contact (DPC) shear wave transducers separated by equidistant transmitter/receiver arrays. The probe is equipped with a commercially available portable ultrasonic flaw detector used in the NDT civil engineering industry. To increase the sound pressure generated, the number of transducers in the novel probe is increased to 32 transducers. In addition, the timed excitation of each transducer directs a focused beam of sound to a specific angle and distance based on the previously calculated delay time. This narrows the sensitivity of test volume and improves the signal-to-noise ratio of the received signals. In this paper, the newly designed phased array borehole probe is validated by beam computation in the CIVA software and experimental investigations on a half-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction methods, it is expected that an optimised radiation pattern of the probe will improve the signal quality and thus increase the reliability of the imaging results. This is an important consideration for the construction of safe sealing structures for the safe disposal of radioactive or toxic waste. KW - Ultrasound KW - Phased array KW - Concrete KW - Borehole PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565722 DO - https://doi.org/10.3390/s22249823 SN - 1424-8220 VL - 22 IS - 24 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-56572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Johann, Sergej A1 - Strangfeld, Christoph A1 - Müller, Maximilian A1 - Bartholmai, Matthias ED - Aulova, Alexandra ED - Rogelj Ritonja, Alenka ED - Emri, Igor T1 - RFID sensor systems embedded in concrete - requirements for long-term operation N2 - One of the more difficult tasks for structural health monitoring is the continuous evaluation of the stability and load capacity of the building materials. This knowledge can be won, e.g., by taking material samples at the examining place with the drawback of partly destroying the structure. To avoid this, modern sensor and communication technologies offer promising methods for non-destructive testing. To address the tasks for monitoring of concrete structures, in the presented study, different sensors were combined with RFID transponders and embedded in concrete components. T2 - 33rd Danubia - Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Structure health monitoring KW - Concrete KW - Embedded KW - RFID sensors PY - 2016 SN - 978-961-94081-0-0 SP - 68 EP - 69 CY - Ljubljana AN - OPUS4-37535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Johann, Sergej T1 - RFID sensor systems embedded in concrete - requirements for long-term operation N2 - One of the more difficult tasks for structural health monitoring is the continuous evaluation of the stability and load capacity of the building materials. This knowledge can be won, e.g., by taking material samples at the examining place with the drawback of partly destroying the structure. To avoid this, modern sensor and communication technologies offer promising methods for non-destructive testing. To address the tasks for monitoring of concrete structures, in the presented study, different sensors were combined with RFID transponders and embedded in concrete components. T2 - 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Concrete KW - Embedded KW - RFID sensors KW - Structure health monitoring PY - 2016 AN - OPUS4-37533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Moisture testing and mapping N2 - Presentation of the Non-destructive testing and evaluation advanced training workshop of division 8.2 regarding moisture measurements. T2 - NDT&E Advanced Training Workshop CY - Berlin, Germany DA - 21.06.2023 KW - Material moisture KW - Moisture transport KW - Building materials KW - Concrete KW - Moisture measurement techniques PY - 2023 AN - OPUS4-57799 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon T1 - Thickness determination of polymeric multilayer surface protection systems for concrete by means of pulse thermography N2 - So far, only destructive measurement techniques are available for thickness determination of polymer based surface protection systems for concrete surfaces. Pulse thermography appears to be well suited for non-destructive thickness evaluation in these systems. Here, we present first results of the development of a respective measurement and analysis procedure. Since surface protection systems consist of a number of layers, a model for the calculation of the surface temperature of a multi-layer structure on an infinite (concrete) substrate in pulse thermography setup was developed. It considers semitransparency of the upmost layer and thermal losses at the surface. It also supports the use of an arbitrary temporal shape of the heating pulse to properly describe the measurement conditions for different heat sources. First experimental results regarding the verification of the model are presented. Funding by the Federal Ministry for Economic Affairs and Energy is gratefully acknowledged. T2 - QNDE 2016 CY - Atlanta, GA, USA DA - 17.07.2016 KW - Thermography KW - Analytical model KW - Surface protection KW - Concrete KW - Semitransparency KW - Thickness PY - 2016 AN - OPUS4-36984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Inspection and monitoring of massive concrete structures by innovative ultrasonic methods N2 - Presentation on recent progress in ultrasinic testing and monitoring of concrete for massive structures. First, a new instrument (LAUS) for ultrasonic echo testing of thicknesses up to 5 m is shown. A new method to provide better images of the concrete interior, Reverse Mitem Migration (RTM)is presented. Second, the use of embedded ultrasonic transducers and data processing methods borrowed from seismology to detect subtle changes in concrete are documented. T2 - NUCCON 2016 CY - Helsinki, Finland DA - 31.10.2016 KW - Ultrasound KW - Concrete KW - Imaging KW - Monitoring KW - Nuclear PY - 2016 AN - OPUS4-38181 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Progress in non-destructive testing and monitoring of concrete N2 - The presentation will give an overview on non-destructive testing techniques being developed at the Federal Institute for Materials Research and Testing, Germany (BAM). This includes ultrasonic methods, ground penetration radar, Laser-Induced Breakdown Spectroscopy (LIBS), infrared thermography, pile testing, sensor technology and building scanner. A focus of the talk will be ultrasonic methods, which are well established in various aspects of concrete testing. They are used for imaging the interior geometry of constructions, estimation of concrete strength or monitoring lab investigations. However, so far the detection of distributed damages, especially in an early stage, has been almost impossible. The arrival of new technologies as embedded transducers and sensitive data processing techniques adopted from seismology has opened new field of work. Recent research has been focused to detect changes in concrete elements induced by stress, temperature, moisture or chemical attacks by permanent monitoring. Techniques as Coda Wave Interferometry can resolve changes in ultrasonic velocity in the order of 1*10-5. In addition, many researchers believe that the investigation of nonlinear effects can be used to characterize damages. The presentation will give a wrap up of ultrasonic techniques currently used in practice. This will include echo based methods as multi-channel/multi-offset imaging of structural elements using commercial and prototype devices. Imaging methods as SAFT and RTM will be shortly discussed. The focus will be on the emerging techniques used for monitoring. New types of sensors will be presented as well as the devices used in laboratory and field applications. Insight will be given on the various influence factors on ultrasonic signals and various ways of feature extraction and data processing. The results of lab experiments will be shown to demonstrate the detection of various kind of damages from mechanical load, ASR, corrosion to fatigue. The experiences with our first installations in real constructions (bridges, tunnel) will also be presented. T2 - CIES Research Seminar, University of New South Wales CY - Sydney, Australia DA - 13.12.2016 KW - Ultrasound KW - Concrete KW - Monitoring KW - Imaging PY - 2016 AN - OPUS4-38731 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - State-of-the-art of ultrasonic monitoring of concrete N2 - Ultrasonic methods are well established in various aspects of concrete testing. They are used for imaging the interior geometry of constructions, estimation of concrete strength or monitoring lab investigations. However, so far the detection of distributed damages, especially in an early stage, has been almost impossible. The arrival of new technologies as embedded transducers and sensitive data processing techniques adopted from seismology has opened new field of work. Recent research has been focused to detect changes in concrete elements induced by stress, temperature, moisture or chemical attacks by permanent monitoring. Techniques as Coda Wave Interferometry can resolve changes in ultrasonic velocity in the order of 1*10-5. In addition, many researchers believe that the investigation of nonlinear effects can be used to characterize damages. The workshop will give a wrap up of ultrasonic techniques currently used in practice. This will include echo based methods as multi-channel/multi-offset imaging of structural elements using commercial and prototype devices. Imaging methods as SAFT and RTM will be shortly discussed. The focus will be on the emerging techniques used for monitoring. New types of sensors will be presented as well as the devices used in laboratory and field applications. Insight will be given on the various influence factors on ultrasonic signals and various ways of feature extraction and data processing. The results of lab experiments will be shown to demonstrate the detection of various kind of damages from mechanical load, ASR, corrosion to fatigue. The experiences with or first installations in real constructions (bridges, tunnel) will also be presented. T2 - The 8th Australian Network of Structural Monitoring Annual Workshop CY - Melbourne, Australia DA - 29.11.2016 KW - Ultrasound KW - Concrete KW - Monitoring KW - Imaging PY - 2016 AN - OPUS4-38727 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Coda wave interferometry used for monitoring of concrete constructions N2 - Concrete is known to be a very useful, flexible and durable construction material. However, due to excess load, fatigue, chemical processes, freeze-thaw or reinforcement corrosion concrete may suffer from degradation. If detected too late, repair is difficult and expensive. The propagation of ultrasonic waves is influenced by changes in the properties and structure of the material, including, but not limited to, stress, temperature, moisture content and microcracking. Ultrasonic velocieties thus may serve as indicators for structural health. Traditional ultrasonic methods as transmission time of flight measurements are used since decades, but are not sensible enough to show subtle changes. Coda Wave Interferometry (CWI), originally developed in seismology to detect stress changes in the earth's crust uses the information in the late part of ultrasonic signals originating from multiple reflections and scattering. Since a few years it is used by several researchers for lab experiments on concrete. Meanwhile specialized sensors to be embedded in concrete have been developed. We have conducted several lab and a few field experiments, which will be reported here. The capabilities and limitations of CWI are summarized. T2 - Jahrestagung der DGG CY - Münster DA - 14.03.2016 KW - Coda wave interferometry KW - Concrete KW - Monitoring KW - Ultrasound PY - 2016 AN - OPUS4-35710 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Progress in non-destructive testing and monitoring of concrete N2 - Überblicksvortrag zu Aktivitäten von BAM-8.2 T2 - Seminar der Universität Lund, Fakultät, Technische Geologie und NDT CY - Lund, Sweden DA - 8.3.2018 KW - Concrete KW - Non-Destructive Testing PY - 2018 AN - OPUS4-44575 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultrasound: From Imaging to Monitoring N2 - Review of ultrasonic echo imaging and ultrasonic monitoring techniques applied to concrete structures, especially bridges. Includes newest research results from BAM. T2 - Transport Research Board Annual Meeting, Workshop 1647 CY - Washington, DC, USA DA - 6.1.2018 KW - Ultrasound KW - Imaging KW - Monitoring KW - Concrete KW - Bridges PY - 2018 AN - OPUS4-44587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Detecting subtle changes in concrete with coda wave interferometry N2 - Subtle changes in concrete, caused by stress, temperature or deterioration can be detected by ultrasonic transmission measurements evaluated by coda wave interferometry. Background and examples are presented as well as possibilities to locate damages. T2 - New mathematics for a safer world: wave propagation in heterogeneous materials CY - Edinburgh, UK DA - 12.06.2017 KW - Concrete KW - Ultrasound KW - Coda wave interferometry KW - Monitoring PY - 2017 AN - OPUS4-40580 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultrasonic monitoring of full-scale load experiments N2 - Previous work has shown that ultrasonic monitoring using externally applied or embedded transducers and imaging methods based on coda wave interferometry are able to detect subtle changes in concrete elements. In this study, a limited number of embedded transducers has been used to monitor changes in several 12 m long two-span concrete beams subjected to point or linear loads until failure. The ultrasonic results showed the high sensitivity to stress changes and the nonlinear character of the associated effects. However, the ultrasonic features showed a very good correlation to several conventional monitoring parameters. For higher loads (significant amount of cracking), the technique had to be modified to cope with large wave velocity variations and high decorrelation compared to the reference signal. Using a very simple imaging procedure, the 2D stress field inside the beam has been visualized including inhomogeneities and artifact at places where cracking occurred at higher loads. The technique has the potential to be included in real time monitoring systems. T2 - ASNT SMT/NDT-CE 2018 CY - New Brunswick, NJ, USA DA - 27.8.2018 KW - Concrete KW - Monitoring KW - Ultrasound KW - Coda wave interferometry PY - 2018 AN - OPUS4-45827 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Non-destructive Evaluation for Nuclear Power Plant concrete infrastructure N2 - The ageing and decommissioning of nuclear concrete infrastructure (e. g. safety containments) as well as the building and closure of waste repositories gives new challenges to non-destructive testing. For example, the quality assurance of very thick concrete structures is beyond the limitations of commercial ultrasonic instrumentation. The presentation introduces typical testing tasks and the application of state of the art NDT techniques. In addition, it describes some new developments in ultrasonic testing and monitoring. Specifically, the application of the unique deep penetration system LAUS is shown. Ultrasonic monitoring using embedded transducers to check for subtle and sudden changes in the material is introduced as well. T2 - Aalto University Special Guest Seminar CY - Espoo, Finland DA - 25.10.2018 KW - Ultrasound KW - Concrete KW - Nuclear PY - 2018 AN - OPUS4-46425 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst T1 - Ultrasonic monitoring of concrete constructions using embedded transducers 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. T2 - International Symposium on Structural Health Monitoring and Nondestructive Testing CY - Saarbrücken, Germany DA - 4.10.2018 KW - Ultrasound KW - Monitoring KW - Concrete PY - 2018 UR - http://www.ndt.net/?id=23542 SN - 1435-4934 VL - 23 IS - 12 SP - 1 EP - 6 PB - NDT.net CY - Kirchwald AN - OPUS4-46842 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Landis, E. A1 - Hassfras, Emiel A1 - Oesch, Tyler A1 - Niederleithinger, Ernst T1 - Relating ultrasonic signals to concrete microstructure using X-ray computed tomography N2 - With a goal to improve our understanding of the relationships between microstructural features and ultrasonic signal behavior, concrete specimens of varying water-to-cement ratio were imaged using X-ray computed tomography (CT), and subsequently subjected to ultrasonic testing. From the CT scans, measurements were made of cement paste density and number of interfaces. Ultrasonic signals produced using a through-transmission configuration were analyzed and fit to a diffusion model to separate absorption from scattering attenuation. The results showed that at the frequencies tested, ultrasonic dissipation rate correlated weakly with paste density, while diffusivity correlated well with number of interfaces, but only if entrained air is considered separately. Cement paste density was found to be very well predicted by diffusivity, leading to a clear power-law relationship between diffusivity and compressive strength. KW - Concrete KW - Ultrasound KW - Strength KW - CT PY - 2021 DO - https://doi.org/10.1016/j.conbuildmat.2020.121124 SN - 0950-0618 VL - 268 SP - Paper 121124, 1 EP - 12 PB - Elsevier Ltd. AN - OPUS4-52073 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Xin A1 - Chakraborty, J. A1 - Niederleithinger, Ernst T1 - Noise Reduction for Improvement of Ultrasonic Monitoring Using Coda Wave Interferometry on a Real Bridge N2 - Reinforced concrete bridges are iconic parts of modern infrastructure. They are designed for a minimum service life of 100 years. However, environmental factors and/or inappropriate use might cause overload and accelerate the deterioration of bridges. In extreme cases, bridges could collapse when necessary maintenance lacks. Thus, the permanent monitoring for structure health assessment has been proposed, which is the aim of structural health monitoring (SHM). Studies in laboratories have shown that ultrasonic (US) coda wave interferometry (CWI) using diffuse waves has high sensitivity and reliability to detect subtle changes in concrete structures. The creation of micro-cracks might be recognized at an early stage. Moreover, large-volume structures can be monitored with a relatively small number of US transducers. However, it is still a challenge to implement the CWI method in real SHM practical applications in an outdoor environment because of the complex external factors, such as various noise sources that interfere with the recorded signals. In this paper, monitoring data from a 36-m long bridge girder in Gliwice, Poland, instrumented with embedded US transducers, thermistors, and vibrating wire strain gauges, is presented. Noise estimation and reductionmethods are discussed, and the influence of traffic, as well as temperature variation, are studied. As a result, the relative velocity variation of US waves following the temperature change with a very high precision of 10−4% is shown, and a good bridge health condition is inferred. The influence of lightweight real traffic is negligible. The study verified the feasibility of the implementation of the CWI method on real bridge structures. KW - Ultrasound KW - Coda Wave Interferometry KW - Noise KW - Concrete KW - Bridge PY - 2021 DO - https://doi.org/10.1007/s10921-020-00743-9 VL - 40 IS - 1 SP - Article number: 14 PB - Springer Nature AN - OPUS4-52052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Ultrasonic coda wave monitoring of concrete structures: First experiences with large-scale experiments and real structures N2 - Ultrasonic monitoring, making use of the sensitivity of the coda of repeated transmission meas-urements to changes in stress, temperature, moisture, as well as localized or distributed damage, has gotten at-tention in structural health monitoring (SHM) research recently. Analysis methods such as coda wave inter-ferometry (CWI), including its nonlinear extension, have been shown to be able to measure ultrasonic wave velocity changes with a 1∙10-5 resolution, while indicators such as cross-correlation or cross-coherence have been used to distinguish between reversible and irreversible changes. Several small- and large-scale laboratory experiments have demonstrated that stress changes in structures can be captured or damage detected in a very early stage. The use of this technique for pre-warning before failure are currently under investigation, as well as detailed research on the physical causes and the connection between ultrasonic wave properties and materi-al/structural behavior. Recently, several of large-scale laboratory and real structures have been instrumented with embedded ultrasonic transducers to gather experience and evidence on how to use this technology in re-al-world applications. Preliminary results from installations on a new bridge, an existing bridge, a tunnel, a la-boratory earthquake test as well as a historic stadium in Germany, Poland, and the United States, respectively, are presented. Environmental influences (mainly temperature) and validation by load tests are discussed. T2 - IABMAS 2020 CY - Online meeting DA - 11.04.2021 KW - Ultrasound KW - Monitoring KW - Coda wave interferometry KW - Concrete KW - Bridges PY - 2021 AN - OPUS4-54167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maack, Stefan T1 - Practical procedure for the precise measurement of geometrical tendon positions in concrete with ultrasonic echo N2 - Existing concrete structures were usually designed for lifetimes of several decades. The current and urgently required efforts to increase sustainability and protect the environment will likely result in extended service lives up to 100 years. To achieve such objectives, it is required to assess structures over their entire lifecycles. Non-destructive testing (NDT) methods can reliably support the assessment of existing structures during the construction, operational, and decommissioning phases. One of the most important and safety-relevant components of a prestressed concrete structure are the tendons. NDT methods such as the ultrasonic echo method are suitable for both the detection and the localization of the tendons, i.e., the measurement of their geometrical position inside the component. The uniqueness of structures, concrete heterogeneity, and varying amounts of secondary components such as the reinforcement represent obstacles in the application of these methods in practice. The aim of this contribution is to demonstrate a practicable procedure, that can be used in the field to determine the parameters required for the measuring data analysis without extensive knowledge about the investigated components. For this purpose, a polyamide reference specimen is used to show which steps are required to obtain reliable imaging information on the position of tendons from the measurement data. The procedure is then demonstrated on a concrete test specimen that covers various relevant and practice-oriented test scenarios, such as varying tendon depths and component thicknesses. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2022) CY - Cape Town, South Africa DA - 03.10.2022 KW - Validation KW - Non-destructive testing KW - Ultrasonic KW - Reconstruction KW - Concrete KW - Tendon duct PY - 2022 AN - OPUS4-55999 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Niederleithinger, Ernst A1 - Wang, Xin A1 - Epple, Niklas A1 - Schumacher, T. A1 - Ahmend, S. A1 - Klikowicz, P. ED - Yokota, H. ED - Frangopol, D. W. T1 - Ultrasonic coda wave monitoring of concrete structures: First experiences with large-scale experiments and real structures N2 - Ultrasonic monitoring, making use of the sensitivity of the coda of repeated transmission meas-urements to changes in stress, temperature, moisture, as well as localized or distributed damage, has gotten at-tention in structural health monitoring (SHM) research recently. Analysis methods such as coda wave inter-ferometry (CWI), including its nonlinear extension, have been shown to be able to measure ultrasonic wave velocity changes with a 1∙10-5 resolution, while indicators such as cross-correlation or cross-coherence have been used to distinguish between reversible and irreversible changes. Several small- and large-scale laboratory experiments have demonstrated that stress changes in structures can be captured or damage detected in a very early stage. The use of this technique for pre-warning before failure are currently under investigation, as well as detailed research on the physical causes and the connection between ultrasonic wave properties and materi-al/structural behavior. Recently, several of large-scale laboratory and real structures have been instrumented with embedded ultrasonic transducers to gather experience and evidence on how to use this technology in re-al-world applications. Preliminary results from installations on a new bridge, an existing bridge, a tunnel, a la-boratory earthquake test as well as a historic stadium in Germany, Poland, and the United States, respectively, are presented. Environmental influences (mainly temperature) and validation by load tests are discussed. KW - Coda wave interferometry KW - Structural health monitoring KW - Ultrasound KW - Concrete KW - Bridges PY - 2021 SN - 978-0-367-23278-8 DO - https://doi.org/10.1201/9780429279119-345 SP - 2525 EP - 2531 PB - Taylor & Francis CY - London, UK AN - OPUS4-54168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -