TY - JOUR A1 - Mellios, Nikolaos A1 - Kruschwitz, Sabine A1 - Spyrdis, Panagiotis T1 - Performance Prediction of Anchors in SFRC using Minimally Invasive and Non‐Destructive Techniques N2 - AbstractFastenings are crucial for the upgrade of existing structures, by either enhancing structural components or modernising and expanding structures and structural systems. Whilst concrete is prevailing in the existing building stock, new types of concrete composites are increasingly used to improve the sustainability and overall structural performance of built assets. The addition of short dispersed fibres is a material technology with several applications. This paper addresses the synergy of fastening elements, introducing localised loads in concrete substrates, and of fibres, particularly in terms of the fibre orientation and density in the load application area, which is a significant quality aspect. The possibility to forecast this synergy based on non‐destructive or minimally invasive testing methods is an efficient tool to increase confidence in the design load‐bearing performance of the anchorages. Initially, previous literature and own investigations on such techniques are presented. Furthermore, a methodology is presented on associating such information to predict a single anchor's resistance on the basis of sophisticated non‐linear analyses and testing with engineered fibres alignments. T2 - Annual Meeting of the European-Association-on-Quality-Control-of-Bridges-and-Structures (EUROSTRUCT) CY - Vienna, Austria DA - 25.09.2023 KW - Minimally-invasive evaluation KW - Fastenings KW - Anchorage to concrete KW - Steel fibre reinforced concrete KW - Non-destructive evaluation NDE KW - Non-destructive testing NDT PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609223 DO - https://doi.org/10.1002/cepa.2115 VL - 69 IS - 5 SP - 1455 EP - 1463 PB - Wiley AN - OPUS4-60922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - McNeil, Sue A1 - Adey, Bryan A1 - Anastasopoulos, Panagiotis Ch. A1 - Chu, James C. A1 - Derrible, Sybil A1 - Durango-Cohen, Pablo A1 - Francis, Royce A1 - Kruschwitz, Sabine A1 - Labi, Samuel A1 - Li, Joshua A1 - Manuel, Lance A1 - Cunha Marques, Rui A1 - Reilly, Allison A1 - Tesfamariam, Solomon A1 - Sanford, Kristen L. T1 - Journal of Infrastructure Systems: Thirty Years and an Opportunity to Refocus N2 - The editorial reflects on the 30-year journey of the Journal of Infrastructure Systems, highlighting its evolution, interdisciplinary mission, and contributions to the field of civil infrastructure. It traces the journal's history, including the introduction of new paper formats, awards, and its commitment to engaging early-career professionals. Looking forward, the journal emphasizes its focus on complex, system-level challenges, encouraging submissions that integrate engineering with data-driven, cross-disciplinary approaches, particularly in areas like smart infrastructure, climate resilience, and sustainability. The editorial concludes with gratitude to contributors and a call for continued collaboration to advance the understanding and management of infrastructure systems. KW - Maintenance KW - Infrastructure systen KW - Transportation KW - Repair KW - Climate resilience KW - Refurbishment PY - 2025 DO - https://doi.org/10.1061/JITSE4.ISENG-2690 VL - 31 IS - 1 SP - 1 EP - 2 PB - American Society of Civil Engineers (ASCE) AN - OPUS4-62773 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martin, T. A1 - Zimmermann, E. A1 - Klitzsch, N. A1 - Hördt, A. A1 - Huisman, J. A. A1 - Radic, T. A1 - Kruschwitz, Sabine T1 - Round-robin test of SIP laboratory measurements using electrical test networks N2 - This study presents the results of an interlaboratory test designed to evaluate the accuracy of spectral induced polarization (SIP) measurements using controlled electrical test networks. The study, conducted in Germany since 2006, involved 12 research institutes, six different impedance measurement devices and four types of electrical test networks specifically designed to evaluate phase shift errors in SIP measurements. The test networks, with impedances ranging from 100 to 150 kΩ, represent high-impedance samples with different phase characteristics, and pose the measurement challenges typical of such samples, including high contact impedances and parasitic capacitances. Four key findings emerged from the study: (1) Impedance measurements across all devices showed deviations within 1 per cent over a wide frequency range (0.001–1000 Hz); (2) phase errors remained below 1 mrad up to 100 Hz for most devices, but increased at higher frequencies due to parasitic capacitances and electromagnetic coupling effects; (3) lab-specific instruments have lower phase errors than field instruments when used in a laboratory environment, primarily due to the effects of long cables and too low input impedances of the field instruments; and (4) short cables and driven shielding technology effectively minimized parasitic capacitance and improved measurement accuracy. The study highlights the usefulness of test networks in assessing the accuracy of SIP measurements and raises awareness of the various factors influencing the quality of SIP data. KW - Induced polarization KW - Electrical properties KW - Electrical resistivity tomography (ERT) PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-631522 DO - https://doi.org/10.1093/gji/ggaf153 SN - 0956-540X VL - 242 IS - 1 SP - 1 EP - 13 PB - Oxford University Press (OUP) AN - OPUS4-63152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martin, T A1 - Zimmermann, E A1 - Klitzsch, N A1 - Hördt, A A1 - Huisman, J A A1 - Radic, T A1 - Kruschwitz, Sabine T1 - Round-robin test of SIP laboratory measurements using electrical test networks N2 - This study presents the results of an interlaboratory test designed to evaluate the accuracy of spectral induced polarization (SIP) measurements using controlled electrical test networks. The study, conducted in Germany since 2006, involved 12 research institutes, six different impedance measurement devices and four types of electrical test networks specifically designed to evaluate phase shift errors in SIP measurements. The test networks, with impedances ranging from 100 to 150 kΩ, represent high-impedance samples with different phase characteristics, and pose the measurement challenges typical of such samples, including high contact impedances and parasitic capacitances. Four key findings emerged from the study: (1) Impedance measurements across all devices showed deviations within 1 per cent over a wide frequency range (0.001–1000 Hz); (2) phase errors remained below 1 mrad up to 100 Hz for most devices, but increased at higher frequencies due to parasitic capacitances and electromagnetic coupling effects; (3) lab-specific instruments have lower phase errors than field instruments when used in a laboratory environment, primarily due to the effects of long cables and too low input impedances of the field instruments; and (4) short cables and driven shielding technology effectively minimized parasitic capacitance and improved measurement accuracy. The study highlights the usefulness of test networks in assessing the accuracy of SIP measurements and raises awareness of the various factors influencing the quality of SIP data. KW - Induced polarization KW - Electrical properties KW - Electrical resistivity tomography (ERT) PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-636755 DO - https://doi.org/10.1093/gji/ggaf153 SN - 0956-540X VL - 242 IS - 1 SP - 1 EP - 13 PB - Oxford University Press (OUP) AN - OPUS4-63675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lorenzoni, Renata A1 - Fritsch, Tobias A1 - Kruschwitz, Sabine A1 - Bruno, Giovanni A1 - Schmidt, Wolfram T1 - Mechanical analysis of cement-biochar composites using in-situ X-ray microtomography and digital volume correlation N2 - This study addresses biochar as a potential carbon-sequestering filler in cement and examines its effect on mechanical properties using X-ray computed tomography (XCT) and digital volume correlation (DVC). DVC was reliably used to measure global displacement and has proven to be an effective method for correcting displacement data obtained from mechanical tests conducted without traditional instrumentation, such as extensometer. This made it possible to measure strain and Young’s modulus accurately. The results demonstrate that while 5 vol% biochar replacement had minimal effect on mechanical properties, a 25 vol% biochar replacement caused a 35 % reduction in Young’s modulus and 40 % reduction in the ultimate compressive strength. Additionally, DVC detected strain concentrations and predicted material failure locations even when cracks could not be quantified using XCT alone. Moreover, the study reveals that biochar particles, due to their sharp geometry, increase internal shear strain during uniaxial compression, unlike round phases such as pores. KW - Cementitious materials KW - Biochar KW - Mechanical proprieties KW - In-situ X-ray microtomography KW - Digital volume correlation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638065 DO - https://doi.org/10.1016/j.conbuildmat.2025.142511 SN - 1879-0526 VL - 490 PB - Elsevier Ltd. AN - OPUS4-63806 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lai, W. W.L. A1 - Chang, R.K.W. A1 - Völker, Christoph A1 - Cheung, B. W.Y. T1 - GPR wave dispersion for material characterization N2 - This paper studies the dispersion of GPR wave’s phase velocity at different wideband frequencies in plywood and concrete with varying moisture content. This study makes use of two GPR antennas with 2 GHz centre frequency operating in wide angle reflection and refraction (WARR) mode and with computation of spectral analysis of the surface wave (SASW). Computation of phase velocities is based on the Acquisition of the cross-power spectrum and phase unwrap of two distorted ground waves at positions Closer to and farther away from the transmitting antenna. The velocities of the ground waves are found to experience greater dispersion in low frequency regimes within the effective frequency bandwidths determined and thresholded by time–frequency analysis (TFA) and coherence plotting of the ground waves. This study validates not only the methodology, but also identifies the optimal distance between the first (Rx1) and second (Rx2) receivers as k/2, which is based on a fixed transmitter (Tx) minus the first Receiver (Rx1) distance. It serves as an indication of changeable separation distance when other lower frequency GPR is used because the distances of Tx-Rx1 and Rx1-Rx2 are wavelength dependent and thus also frequency dependent. Effects of moisture contents and chloride contamination in concrete were also characterized according to the dispersion plots . that wave traelling in lower frequencies in GPR wave is much decelerated than that in higher frequencies. This research also contributes to the building of the ‘‘GPRWARR machine” suggested in Annan and Jackson (2017) [1], within which the effects of wave Dispersion on phase velocity can be inversely modelled to characterize variations in the material properties of infrastructure as a means of detecting surface damage. KW - Ground penetrating radar KW - Wide angle reflection and refraction PY - 2021 DO - https://doi.org/10.1016/j.conbuildmat.2021.122597 SN - 0950-0618 VL - 282 SP - 122597 PB - Elsevier Ltd. AN - OPUS4-52197 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kruschwitz, Sabine A1 - Oesch, T. A1 - Mielentz, Frank A1 - Meinel, Dietmar A1 - Spyridis, P. T1 - Non-Destructive Multi-Method Assessment of Steel Fiber Orientation in Concrete N2 - Integration of fiber reinforcement in high-performance cementitious materials has become widely applied in many fields of construction. One of the most investigated advantages of steel Fiber reinforced concrete (SFRC) is the deceleration of crack growth and hence its improved sustainability. Additional benefits are associated with its structural properties, as fibers can significantly increase the ductility and the tensile strength of concrete. In some applications it is even possible to entirely replace the conventional reinforcement, leading to significant logistical and environmental benefits. Fiber reinforcement can, however, have critical disadvantages and even hinder the Performance of concrete, since it can induce an anisotropic material behavior of the mixture if the fibers are not appropriately oriented. For a safe use of SFRC in the future, reliable non-destructive testing (NDT) methods need to be identified to assess the fibers’ orientation in hardened concrete. In this study, ultrasonic material testing, electrical impedance testing, and X-ray computed tomography have been investigated for this purpose using specially produced samples with biased or random Fiber orientations. We demonstrate the capabilities of each of these NDT techniques for fiber orientation measurements and draw conclusions based on these results about the most promising areas for future research and development. KW - Spectral induced polarization KW - Steel fiber reiniforced concrete KW - Fiber orientation KW - Non-destructive testing KW - Micro-computed tomography KW - Ultrasound PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543520 DO - https://doi.org/10.3390/app12020697 VL - 12 IS - 2 SP - 1 EP - 14 PB - MDPI CY - Basel Switzerland AN - OPUS4-54352 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 - TY - JOUR A1 - Kruschwitz, Sabine A1 - Halisch, M. A1 - Dlugosch, R. A1 - Prinz, Carsten T1 - Toward a better understanding of low-frequency electrical relaxation - An enhanced pore space characterization N2 - Relaxation phenomena observed in the electrical low-frequency range (approximately 1 mHz-10 kHz) of natural porous media like sandstones is often assumed to be directly related to the dominant (modal) pore throat sizes measured, for instance, with mercury intrusion porosimetry. Attempts to establish a universally valid relationship between pore size and peak Spectral Induced Polarization (SIP) relaxation time have failed, considering sandstones from very different origins and featuring great variations in textural and chemical compositions as well as in geometrical pore space properties. In addition working with characteristic relaxation times determined in Cole-Cole or Debye decomposition fits to build the relationship have not been successful. In particular, samples with narrow pore throats are often characterized by long SIP relaxation times corresponding to long “characteristic length scales” in these media, assuming that the diffusion coefficients along the electrical double layer were constant. Based on these observations, three different types of SIP relaxation can be distinguished. We present a new way of assessing complex pore spaces of very different sandstones in a multi-methodical approach to combine the benefits of mercury intrusion porosimetry, micro-computed tomography, and nuclear magnetic resonance. In this way, we achieve much deeper insight into the pore space due to the different resolutions and sensitivities of the applied methods to both pore constrictions (throats) and wide pores (pore bodies). We experimentally quantify pore aspect ratios and volume distributions within the two pore regions. We clearly observe systematic differences between three SIP relaxation types identified previously and can attribute the SIP peak relaxation times to measured characteristic length scales within our materials. We highlight selected results for a total of nine sandstones. It seems that SIP relaxation behavior depends on the size difference of the narrow pore throats to the wide pore bodies, which increases from SIP Type 1 to Type 3. KW - µ-CT KW - Spectral induced polarization KW - Nuclear magnetic resonance KW - Pore space PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509763 DO - https://doi.org/10.1190/GEO2019-0074.1 SN - 0016-8033 VL - 85 IS - 4 SP - MR257 EP - MR270 PB - Society of Exploration Geophysicists AN - OPUS4-50976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krautz, M. A1 - Beyer, L. A1 - Funk, Alexander A1 - Waske, Anja A1 - Weise, B. A1 - Freudenberger, J. A1 - Gottschall, T. T1 - Predicting the dominating factors during heat transfer in magnetocaloric composite wires N2 - Magnetocaloric composite wires have been studied by pulsed-field measurements up to μ0ΔH = 10 T with a typical rise time of 13 ms in order to evaluate the evolution of the adiabatic temperature change of the core, ΔTad, and to determine the effective temperature change at the surrounding steel jacket, ΔTeff, during the field pulse. An inverse thermal hysteresis is observed for ΔTad due to the delayed thermal transfer. By numerical simulations of application-relevant sinusoidal magnetic field profiles, it can be stated that for field-frequencies of up to two field cycles per second heat can be efficiently transferred from the core to the outside of the jacket. In addition, intense numerical simulations of the temperature change of the core and jacket were performed by varying different parameters, such as frequency, heat capacity, thermal conductivity and interface resistance in order to shed light on their impact on ΔTeff at the outside of the jacket in comparison to ΔTad provided by the core. KW - Composite KW - Heat transfer KW - Numerical simulation KW - Pulsed magnetic field PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513791 DO - https://doi.org/10.1016/j.matdes.2020.108832 VL - 193 SP - 108832 PB - Elsevier Ltd. AN - OPUS4-51379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -