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 - Mechtcherine, Viktor A1 - Muthukrishnan, Shravan A1 - Robens-Radermacher, Annika A1 - Wolfs, Rob A1 - Versteege, Jelle A1 - Menna, Costantino A1 - Ozturk, Onur A1 - Ozyurt, Nilufer A1 - Roupec, Josef A1 - Richter, Christiane A1 - Jungwirth, Jörg A1 - Miranda, Luiza A1 - Ammann, Rebecca A1 - Caron, Jean‑François A1 - de Bono, Victor A1 - Monte, Renate A1 - Navarrete, Iván A1 - Eugenin, Claudia A1 - Lombois‑Burger, Hélène A1 - Baz, Bilal A1 - Sinka, Maris A1 - Sapata, Alise A1 - Harbouz, Ilhame A1 - Zhang, Yamei A1 - Jia, Zijian A1 - Kruger, Jacques A1 - Mostert, Jean‑Pierre A1 - Štefančič, Mateja A1 - Hanžič, Lucija A1 - Kaci, Abdelhak A1 - Rahal, Said A1 - Santhanam, Manu A1 - Bhattacherjee, Shantanu A1 - Snguanyat, Chalermwut A1 - Arunothayan, Arun A1 - Zhao, Zengfeng A1 - Mai, Inka A1 - Rasehorn, Inken Jette A1 - Böhler, David A1 - Freund, Niklas A1 - Lowke, Dirk A1 - Neef, Tobias A1 - Taubert, Markus A1 - Auer, Daniel A1 - Hechtl, C. Maximilian A1 - Dahlenburg, Maximilian A1 - Esposito, Laura A1 - Buswell, Richard A1 - Kolawole, John A1 - Isa, Muhammad Nura A1 - Liu, Xingzi A1 - Wang, Zhendi A1 - Subramaniam, Kolluru A1 - Bos, Freek T1 - Mechanical properties of 3D printed concrete: a RILEM 304-ADC interlaboratory study – compressive strength and modulus of elasticity N2 - Traditional construction techniques, such as in-situ casting and pre-cast concrete methods, have well-established testing protocols for assessing compressive strength and modulus of elasticity, including specific procedures for sample preparation and curing. In contrast, 3D concrete printing currently lacks standardized testing protocols, potentially contributing to the inconsistent results reported in previous studies. To address this issue, RILEM TC 304-ADC initiated a comprehensive interlaboratory study on the mechanical properties of 3D printed concrete. This study involves 30 laboratories worldwide, contributing 34 sets of data, with some laboratories testing more than one mix design. The compressive strength and modulus of elasticity were determined under three distinct conditions: Default, where each laboratory printed according to their standard procedure followed by water bath curing; Deviation 1, which involved creating a cold joint by increasing the time interval between printing layers; and Deviation 2, where the standard printing process was used, but the specimens were cured under conditions different from water bath. Some tests were conducted at two different scales based on specimen size—“mortar-scale” and “concrete-scale”—to investigate the size effect on compressive strength. Since the mix design remained identical for both scales, the only variable was the specimen size. This paper reports on the findings from the interlaboratory study, followed by a detailed investigation into the influencing parameters such as extraction location, cold joints, number of interlayers, and curing conditions on the mechanical properties of the printed concrete. As this study includes results from laboratories worldwide, its contribution to the development of relevant standardized testing protocols is critical. KW - Additive manufacturing KW - Digital fabrication KW - Hardened concrete KW - Compressive strength KW - Young's modulus PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634672 DO - https://doi.org/10.1617/s11527-025-02688-9 SN - 1871-6873 VL - 58 IS - 5 SP - 1 EP - 30 PB - Springer Nature AN - OPUS4-63467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bos, Freek A1 - Menna, Constantino A1 - Robens-Radermacher, Annika A1 - Wolfs, Rob A1 - Roussel, Nicolas A1 - Lombois-Burger, Hélène A1 - Baz, Bilal A1 - Weger, Daniel A1 - Nematollahi, Behzad A1 - Santhanam, Manu A1 - Zhang, Yamei A1 - Bhattacherjee, Shantanu A1 - Jia, Zijian A1 - Chen, Yu A1 - Mechtcherine, Viktor T1 - Mechanical properties of 3D printed concrete: a RILEM TC 304-ADC interlaboratory study — approach and main results N2 - To show compliance to structural engineering codes and implement quality control measures, it is critical to obtain reliable mechanical properties of the materials in question. For conventional cast and precast concrete, the experimental procedures and relationships between mechanical properties, the material composition, and the production methods are globally known, but for 3D concrete printing (3DCP), these relations have not yet been established. Previous studies have shown little consistency in results, and the underlying experimental methods have not been established broadly. There is an urgent need to address these issues as the application of 3DCP in practice projects is growing rapidly. Therefore, RILEM TC 304-ADC: Assessment of Additively Manufactured Concrete Materials and Structures has set up a large interlaboratory study into the mechanical properties of 3D printed concrete. This paper presents key elements of the experimental approach detailed in the Study Plan and the supporting considerations. Furthermore, it reports on the response, consisting of 34 contributions from 30 laboratories, detailing global coverage, properties of the applied mixture designs and characteristics of the printing facilities that have been used. Subsequently, some fundamental results from compression, flexural, and E-modulus testing are presented and—considering cast specimens as a reference—discussed. On average, a reduction in strength was found in compression and E-modulus (all tested orientations). For flexure, on the other hand, an increase was found in two testing orientations, while a decrease was observed in the third orientation. Importantly, even though the applied experimental methods were found to be reasonably appropriate to obtain the required data, the differences found between individual contributions are significant and sometimes non-consistent, suggesting that testing on specific material-facility combinations is necessary to reliably determine the mechanical properties of objects produced from them. Furthermore, a theoretical framework needs to be developed to further explain the variations that were observed. Extensive analyses of all acquired data are out of the scope of this contribution, but presented in two associated papers, whereas a third presents the data management approach used to process the approximately 5,000 test results. KW - 3D printed concrete KW - 3DCP KW - Mechanical properties KW - Interlaboratory study PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634631 DO - https://doi.org/10.1617/s11527-025-02686-x VL - 58 IS - 5 SP - 1 EP - 29 PB - Springer Nature AN - OPUS4-63463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolfs, Rob A1 - Versteegen, Jelle A1 - Santhanam, Manu A1 - Bhattacherjee, Shantanu A1 - Bos, Freek A1 - Robens-Radermacher, Annika A1 - Muthukrishnan, Shravan A1 - Menna, Costantino A1 - Ozturk, Onur A1 - Ozyurt, Nilufer A1 - Roupec, Josef A1 - Richter, Christiane A1 - Jungwirth, Jörg A1 - Miranda, Luiza A1 - Ammann, Rebecca A1 - Caron, Jean-François A1 - de Bono, Victor A1 - Monte, Renate A1 - Navarrete, Iván A1 - Eugenin, Claudia A1 - Lombois‑Burger, Hélène A1 - Baz, Bilal A1 - Sinka, Maris A1 - Sapata, Alise A1 - Harbouz, Ilhame A1 - Zhang, Yamei A1 - Jia, Zijian A1 - Kruger, Jacques A1 - Mostert, Jean‑Pierre A1 - Šter, Katarina A1 - Šajna, Aljoša A1 - Kaci, Abdelhak A1 - Rahal, Said A1 - Snguanyat, Chalermwut A1 - Arunothayan, Arun A1 - Zhao, Zengfeng A1 - Mai, Inka A1 - Rasehorn, Inken Jette A1 - Böhler, David A1 - Freund, Niklas A1 - Lowke, Dirk A1 - Neef, Tobias A1 - Taubert, Markus A1 - Auer, Daniel A1 - Hechtl, C. Maximilian A1 - Dahlenburg, Maximilian A1 - Esposito, Laura A1 - Buswell, Richard A1 - Kolawole, John A1 - Isa, Muhammad Nura A1 - Liu, Xingzi A1 - Wang, Zhendi A1 - Subramaniam, Kolluru A1 - Mechtcherine, Viktor T1 - Mechanical properties of 3D printed concrete: a RILEM TC 304-ADC interlaboratory study — flexural and tensile strength N2 - This paper discusses the flexural and tensile strength properties of 3D printed concrete, based on the results of a RILEM TC 304-ADC interlaboratory study on mechanical properties. These properties are determined using different testing techniques, including 3- and 4-point flexural tests, splitting tests, and uniaxial tension tests, on specimens extracted from large 3D printed elements in accordance with a prescribed study plan. The relationship between compressive and flexural or tensile strengths, cast or printed samples, different types of tests, and different loading orientations, are analysed to understand the influence of 3D printing. As expected, the strength can reduce significantly when the main tensile stress is acting perpendicular to the interface between layers. The role of deviations from the standard study procedure, in terms of the time interval between the placing of subsequent layers, or the adoption of a different curing strategy, are also assessed. While the increased time interval significantly impacts the strength in the critical direction, the use of variable curing conditions does not seem to have a clear-cut effect on the strength ratios of the printed to cast specimens. Additionally, the paper looks at the variability in the results for the printed specimens, in order to emphasize the need for multiple replicates for obtaining a proper result. An extensive insight into the aspects affecting the variability is presented in the paper. Finally, with the limited dataset available for specimens tested at a larger scale, it is difficult to arrive at a clear understanding of the role of specimen size (i.e., greater number of layers). KW - 3D concrete printing KW - Digital fabrication KW - Flexural strength KW - Tensile strength KW - Interlayer bond strength PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634655 DO - https://doi.org/10.1617/s11527-025-02687-w SN - 1871-6873 VL - 58 IS - 5 SP - 1 EP - 33 PB - Springer Nature AN - OPUS4-63465 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Robens-Radermacher, Annika A1 - Kujath, Cezary A1 - Bos, Freek A1 - Mechtcherine, Viktor A1 - Unger, Jörg F. T1 - Mechanical properties of 3D printed concrete: a RILEM TC 304-ADC interlaboratory study-Design and implementation of a database system for querying, sharing, and analyzing experimental data N2 - Interlaboratory studies are essential for implementing standardized test methods for new innovative materials or technologies such as 3D concrete printing, certifying reference materials, and validating methods. They provide the basis for recommendations and design standards. Typically, the collected data are used only for one study and are published in paper form, without open access to the raw data files. However, preserving the collected data and analysis procedures in a shareable and reusable way leads to advantages for further usage. New data with the same structure can be added or the data can be analyzed by a new analysis procedure generating new knowledge. Additionally, resources are saved by avoiding the repetition of the same measurements. In line with the recent digitalization trend in material science and engineering, a database for the interlaboratory study on mechanical properties of 3D printed concrete conducted in RILEM Technical Committee 304-ADC is established. The challenges and experiences from defining the data structure, uploading the data, and using the database for evaluations are discussed. The openBIS software is used to create and fill the database, while an export method to an SQLite format is developed and discussed to generate a shareable and reusable database. With the exported database, querying the data is possible independently of a particular data management system. Additionally, examples of data processing with reusable workflows automating the analysis procedure are demonstrated. KW - Data management KW - Interlaboratory study KW - 3D concrete printing KW - Database KW - Reusability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634627 DO - https://doi.org/10.1617/s11527-025-02650-9 SN - 1871-6873 VL - 58 IS - 184 SP - 1 EP - 37 PB - Springer Nature AN - OPUS4-63462 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, Shishir A1 - Provis, J. L. T1 - Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions N2 - The pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer. KW - Alkali-activated materials KW - Steel corrosion KW - Sulfide KW - Chloride PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-528861 DO - https://doi.org/10.1007/s10853-021-06237-x VL - 56 IS - 26 SP - 14783 EP - 14802 PB - Springer Nature AN - OPUS4-52886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rappsilber, Tim A1 - Yusfi, Nawar A1 - Krüger, Simone A1 - Hahn, S.-K. A1 - Fellinger, Tim-Patrick A1 - Krug von Nidda, Jonas A1 - Tschirschwitz, Rico T1 - Meta-analysis of heat release and smoke gas emission during thermal runaway of lithium-ion batteries N2 - Herein a meta-analysis of 76 experimental research papers from 2000 to 2021 is given about possible effects on the thermal runaway of lithium-ion battery cells. Data on the hazards of gas emissions and released heat are related to each other and differentiated by cell properties such as, cell geometry, cathode type or state of charge. Quantitative information on the total heat release in the range of 2.0–112.0 kJ Wh−1, the peak heat release rate in the range of 0.006–2.8 kW Wh−1and the smoke gas emission were extracted, normalized in terms of cell energy (Wh), combined in a data library and compared graphically. The total amount of gas emitted (3–48 mmol Wh−1) as well as the released amount of carbon monoxide (1–161 mg Wh−1) and hydrogen fluoride (2–197 mg Wh−1) were investigated as a function of the state of charge and cell geometry. The analysis reveals that the measured values are significantly influenced by the types of calorimeters and smoke gas analyzers used as well as by the type of thermal runaway trigger. This meta-analysis can serve as an important basis for any risk assessment of lithium-ion batteries. KW - Lithium-ion battery KW - Thermal runaway KW - Cathode active material KW - Heat release KW - Smoke gas emission PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568071 DO - https://doi.org/10.1016/j.est.2022.106579 SN - 2352-152X VL - 60 SP - 1 EP - 15 PB - Elsevier CY - Amsterdam AN - OPUS4-56807 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hilgenfeldt, Verena A1 - Rübner, Katrin A1 - Hahn, Andreas A1 - Steinmetz, Heidrun T1 - Methodology for Assessing Phosphorus Adsorption Kinetics in Novel Constructed Wetland Materials N2 - Although various special materials have been studied for their potential for phosphorus removal in constructed wetlands, varying methodologies make direct comparisons of adsorption capacities observed in laboratory experiments difficult. This paper aims to establish a methodology for determining the optimal ratio of phosphate to material mass for different materials and for achieving the necessary contact time for adsorption isotherms. To minimise the number of experiments required, pretests over 24 h should be repeated to determine the phosphate-specific ratios until they show around 60% of the initial concentration. The tested materials included lava sand and expanded sand (ExS), which showed saturating kinetics curves after 24 to 48 h. However, aggregates containing calcium silicate hydrate (CSH) phases (autoclaved aerated concrete AAC, sand–lime brick SLB, and hydrothermal granules HTG) did not show saturating curves, complicating contact time determination. Consequently, adsorption velocity is proposed to identify the phase with the lowest adsorption rate, which is then used as the contact time in adsorption isotherm experiments. Using this method, adsorption times of 48 h were observed for HTG and SLB, while that for AAC was 24 h. This methodology is intended as an initial approach to establish a common basis for researchers investigating novel materials and make the results comparable. KW - CSH KW - Phosphate elimination KW - Material evaluation KW - Contact time experiments KW - Methodology development KW - Filter substrates PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647443 DO - https://doi.org/10.3390/purification1020007 SN - 3042-6197 VL - 1 IS - 2 SP - 1 EP - 20 PB - MDPI AG CY - Basel, Switzerland AN - OPUS4-64744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Malpass-Evans, R. A1 - McKeown, N. A1 - Jalarvo, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Microscopic molecular mobility of high-performance polymers of intrinsic microporosity revealed by neutron scattering – bend fluctuations and signature of methyl group rotation N2 - Polymers of intrinsic microporosity exhibit a combination of high gas permeability and reasonable permselectivity, which makes them attractive candidates for gas separation membrane materials. The diffusional selective gas transport properties are connected to the molecular mobility of these polymers in the condensed state. Incoherent quasielastic neutron scattering was carried out on two polymers of intrinsic microporosity, PIM-EA-TB(CH3) and its demethylated counterpart PIM-EA-TB(H2), which have high Brunauer–Emmett–Teller surface area values of 1030 m2 g-1 and 836 m2 g-1, respectively. As these two polymers only differ in the presence of two methyl groups at the ethanoanthracene unit, the effect of methyl group rotation can be investigated solely. To cover a broad dynamic range, neutron time-of-flight was combined with neutron backscattering. The demethylated PIM-EA-TB(H2) exhibits a relaxation process with a weak intensity at short times. As the backbone is rigid and stiff this process was assigned to bendand-flex fluctuations. This process was also observed for the PIM-EA-TB(CH3). A further relaxation process is found for PIM-EA-TB(CH3), which is the methyl group rotation. It was analyzed by a jump-diffusion in a three-fold potential considering also the fact that only a fraction of the present hydrogens in PIM-EATB(CH3) participate in the methyl group rotation. This analysis can quantitatively describe the q dependence of the elastic incoherent structure factor. Furthermore, a relaxation time for the methyl group rotation can be extracted. A high activation energy of 35 kJ mol-1 was deduced. This high activation energy evidences a strong hindrance of the methyl group rotation in the bridged PIM-EA-TB(CH3) structure. KW - Polymers of Intrinsic Microporosity KW - Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604114 DO - https://doi.org/10.1039/d4sm00520a SP - 1 EP - 11 PB - RSC AN - OPUS4-60411 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Mitigation of railway-induced ground vibration by soft support elements and a higher bending stiffness of the track N2 - The mitigation of train-induced ground vibrations by track solutions is investigated by calculations and measurements. The calculation by a wavenumber domain method includes the correct vehicle–track interaction and the correct track–soil interaction. Some theoretical results for elastic elements and an increased bending stiffness of the track are presented where the force transfer of the track and the vehicle–track interaction are calculated for the high-frequency dynamic mitigation, and the force distribution along the track is calculated for the low-frequency mitigation which is due to the smoother impulses from the passing static loads. Measurement results for the ground vibration near isolated and un-isolated tracks are given for several under-sleeper pads, for under-ballast mats, and for several under-ballast plates and ballast troughs. The elastic elements yield a resonance frequency of the vehicle–track–soil system and a high-frequency reduction of the dynamic axle loads which depends mainly on the softness of the pads or mats and which can be improved by a higher sleeper mass. In addition, all troughs and most of the soft elements show a low-frequency reduction which is attributed to the scattered impulses of the static axle loads. Besides this main contribution of the article, the problem of a soft reference section on a different soil is discussed and recommendations for better ground vibration measurements of mitigation effects are given. KW - Railway track KW - Elastic elements KW - Bending stiffness KW - Ground vibration KW - Mitigation KW - Lowfrequency reduction KW - Axle impulses PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612568 DO - https://doi.org/10.3390/app14031244 VL - 14 IS - 3 SP - 1 EP - 14 PB - MDPI CY - Basel AN - OPUS4-61256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liao, Chun-Man ED - Zhang, Jian T1 - Modal and Wave Propagation Analysis of Vibration Tests on a Laboratory Building Model Before and After Damage N2 - Weakened structural stiffness is often a consequence of building damage, particularly after severe events such as earthquakes, where compromised structural performance can pose significant risks. To prevent immediate structural failure, an early warning system is essential, which requires inspection of local components. This research aims to achieve that by exploring the wave propagation analysis method, specifically seismic interferometry. Previous studies have applied this method to building structures, treating them as homogeneous layers of grouped floors. By analyzing the wave travel time along the height of these layers, the fundamental period of the building was estimated. However, this approach did not account for local damage or the variability of structural components, similar to the limitations of vibration‐based damage detection methods, which mainly identify global changes. Thus, the goal of this paper is to improve structural health monitoring by examining the sensitivity of wave screening, bridging the gap between nondestructive testing and vibration‐based damage detection. A half‐scale, seven‐story building model, characterized by vertical stiffness irregularity and transverse plan asymmetry, was tested in a laboratory setting. Two vertical sensor arrays were placed near corner columns of different sizes, representing both strong and weak structural areas. These arrays recorded floor accelerations in three directions. The study confirmed the effectiveness of wave propagation analysis for detecting damage along the sensor arrays before and after the earthquake. A transmissibility damage indicator was used to correlate changes in wave velocity, providing a quantitative assessment of damage levels along the wave propagation path. KW - Damage location KW - Laboratory test KW - Soft story KW - Stifness irregular structure KW - Structural health monitoring PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624931 DO - https://doi.org/10.1155/stc/3453150 SN - 1545-2263 VL - 2025 IS - 1 SP - 1 EP - 17 PB - John Wiley & Sons Ltd. AN - OPUS4-62493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Andrés Arcones, Daniel A1 - Weiser, M. A1 - Koutsourelakis, P.-S. A1 - Unger, Jörg F. T1 - Model bias identification for Bayesian calibration of stochastic digital twins of bridges N2 - Simulation-based digital twins must provide accurate, robust, and reliable digital representations of their physical counterparts. Therefore, quantifying the uncertainty in their predictions plays a key role in making better-informed decisions that impact the actual system. The update of the simulation model based on data must then be carefully implemented. When applied to complex structures such as bridges, discrepancies between the computational model and the real system appear as model bias, which hinders the trustworthiness of the digital twin and increases its uncertainty. Classical Bayesian updating approaches aimed at inferring the model parameters often fail to compensate for such model bias, leading to overconfident and unreliable predictions. In this paper, two alternative model bias identification approaches are evaluated in the context of their applicability to digital twins of bridges. A modularized version of Kennedy and O'Hagan's approach and another one based on Orthogonal Gaussian Processes are compared with the classical Bayesian inference framework in a set of representative benchmarks. Additionally, two novel extensions are proposed for these models: the inclusion of noise-aware kernels and the introduction of additional variables not present in the computational model through the bias term. The integration of these approaches into the digital twin corrects the predictions, quantifies their uncertainty, estimates noise from unknown physical sources of error, and provides further insight into the system by including additional pre-existing information without modifying the computational model. KW - Gaussian process KW - KOH KW - Bayesian updating KW - Digital twins KW - Uncertainty quantification PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615519 DO - https://doi.org/10.1002/asmb.2897 SN - 1526-4025 N1 - This work was supported by “C07 - Data driven model adaptation for identifying stochastic digital twins of bridges” from the Priority Program (SPP) 2388/1 “Hundred plus” of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) - Project number 501811638. VL - 417 IS - 3 SP - 1 EP - 26 PB - Wiley CY - Chichester AN - OPUS4-61551 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ji, Y. A1 - Pott, U. A1 - Mezhov, Alexander A1 - Rößler, Ch. A1 - Stephan, D. T1 - Modelling and experimental study on static yield stress evolution and structural build-up of cement paste in early stage of cement hydration N2 - Static yield stress is crucial for concrete, especially for 3D printed concrete, as it determines whether the bottom layer can support the load of the subsequent layers or withstand any potential impulses. A better understanding of the evolution of the static yield stress and its changing mechanism is therefore needed. Under the assumption that hydrate formation follows fractal patterns, this work proposes a model for simulating static yield stress that links the hydration process and bridging possibility. To validate the model, parameters were first obtained from the BNG (Boundary Nucleation Growth) equation fitted with calorimetry data, and the relation of associated hydration rates to sound speed variation rate was analyzed. Results showed that the proposed model predicts well the static yield stress obtained with a penetration test, under varying water-cement ratios and accelerator conditions. The fitted parameter β was found to correlate with size and morphology of the hydration products, suggesting that the model can not only simulate the static yield stress, but also capture the structural build-up information. Furthermore, the decrease in fractal-related β implies that more compact hydrates are formed during hydration. KW - Static yield stress KW - Fractal pattern KW - Hydration process KW - Bridging possibility PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623503 DO - https://doi.org/10.1016/j.cemconres.2024.107710 SN - 1873-3948 VL - 187 SP - 1 EP - 15 PB - Elsevier Ltd. CY - Schweiz AN - OPUS4-62350 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Böhning, Martin T1 - Modernizing FNCT data handling in polymer labs: Towards efficient management N2 - A streamlined Python-based workflow for transforming Full-Notch Creep Test (FNCT) data into organized, machine-actionable formats is presented. The workflow automates the conversion of raw FNCT data from classic CSV and Excel files into structured outputs that facilitate future semantic integration. Emphasizing practical data handling, the approach includes automation scripts for efficient data extraction, transformation, and storage, which culminate in well-ordered files. This transformation paves the way for potential semantic data integration and facilitates access for users with varying levels of digital experience to enhanced data management in polymer research and testing. KW - PE-HD KW - Full-Notch Creep Test (FNCT) KW - Environmental Stress Cracking (ESC) KW - Data Interoperability KW - FAIR Data KW - Semantic Data PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637826 DO - https://doi.org/10.1016/j.commatsci.2025.114085 SN - 0927-0256 VL - 259 SP - 1 EP - 5 PB - Elsevier B.V. AN - OPUS4-63782 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strangfeld, Christoph A1 - Stolpe, Heiko A1 - Wiehle, Philipp T1 - Moisture diffusion affected by the Knudsen effect in temporal changing pore networks N2 - Almost all building materials in civil engineering have an open porosity and interact with or are affected by the environmental conditions. Structures might suffer from effects such as moisture adsorption, carbonation, corrosion, penetration of salt ions and chemical substances, etc. In the hygroscopic range, these processes are mostly driven by diffusion. Due to the confinement of small pores (less than1 µm), the Knudsen effect reduces the molecular diffusion. This reduction can become more significant in case of temporal changing pore systems because of physisorption of water vapor, carbonation, or chemisorption. In this study, unstabilised earth blocks and earth masonry are investigated. In a first step, the pore size distribution of the blocks is measured and sorption isotherms are recorded in experiments. Besides the ordinary physisorption, the involved clay minerals undergo swelling or shrinking due to chemisorption. The following two effects must be considered: first, the reduction of the available pore space by the adsorbed water layer. For this, the Hillerborg sorption theory is used, which is a combination of the well-known Brunauer-Emmett-Teller sorption theory and the Kelvin equation. This allows the computation of adsorbed water layers even in curved pore geometries. Second, the variation of the initial pore size distribution due to chemisorption needs to be modelled. Based on these two models, the effective diffusion coefficient can be predicted. For validation, arrays of relative humidity sensors were embedded into a free-standing earth masonry wall. This monitoring was carried out over more than a year to have a broad variety of environmental conditions and was located in Berlin, Germany. The prediction of the effective diffusion coefficient can also be transferred to other processes and allows the investigation of materials having temporarily changing pore systems. Examples are the carbonation of cementitious materials, alkali silica reaction, calcium leaching of long-lasting structures, etc. These effects are prominent in the meso-pore range and might significantly alter the effective diffusion coefficient. KW - Earth material KW - Material moisture KW - Physisoprtion KW - Chemisorption PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-583811 DO - https://doi.org/10.1016/j.matpr.2023.09.034 SN - 2214-7853 SP - 1 EP - 8 PB - Elsevier Ltd. CY - Amsterdam, Niederlande AN - OPUS4-58381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Huang, J. A1 - Mosane Razavi, Negar A1 - Bojdys, M. J. A1 - Forster, A. B. A1 - Budd, P. M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Molecular Mobility and Gas Transport Properties of Mixed Matrix Membranes Based on PIM‑1 and a Phosphinine Containing Covalent Organic Framework N2 - Polymers with intrinsic microporosity (PIMs) are gaining attention as gas separation membranes. Nevertheless, they face limitations due to pronounced physical aging. In this study a covalent organic framework containing λ5-phosphinine moieties, CPSF-EtO were incorporated as a nanofiller (concentration range 0-10 wt%) into a PIM-1 matrix forming dense films with a thickness of ca. 100 μm. The aim of the investigation was to investigate possible enhancements of gas transport properties and mitigating effects on physical aging. The incorporation of the nanofiller occurred on aggregate level with domains up to 100 nm as observed by T-SEM and confirmed by X-ray scattering. Moreover, the X-ray data show that the structure of the microporous network of the PIM-1 matrix is changed by the nanofiller. As the molecular mobility is fundamental for gas transport as well as for physical aging, the study includes dielectric investigations of pure PIM-1 and PIM-1/CPSF-EtO mixed matrix membranes to establish a correlation between the molecular mobility and the gas transport properties. Using the time-lag method the gas permeability and the permselectivity were determined for N2, O2, CH4 and CO2 for samples with variation in filler content. A significant increase in the permeability of CH4 and CO2 (50 % increase compared to pure PIM-1) was observed for a concentration of 5 wt% of the nanofiller. Furthermore, the most pronounced change in the permselectivity was found for the gas pair CO2/N2 at a filler concentration of 7 wt%. KW - Polymers of Intrinsic Microporosity KW - Nanocomposites PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595031 DO - https://doi.org/10.1021/acs.macromol.3c02419 SN - 0024-9297 VL - 57 IS - 4 SP - 1829 EP - 1845 PB - ACS Publications AN - OPUS4-59503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Battig, Alexander A1 - Abdou-Rahaman Fadul, Naïssa A1 - Frasca, Daniele A1 - Schulze, Dietmar A1 - Schartel, Bernhard T1 - Multifunctional graphene nanofiller in flame retarded polybutadiene/chloroprene/carbon black composites N2 - To curtail flammability risks and improve material properties, flame retardants (FRs) and fillers are mixed into rubbers. High loadings of aluminum trihydroxide (ATH) and carbon black (CB) are the most used FRs and reinforcing additive, respectively, in rubbers. To reduce loading without losing mechanical properties, partial substitution of ATH as well as CB by low amounts of multilayer graphene (MLG) nanoparticles is investigated. The high aspect ratio MLG is made of ten graphene sheets. In polybutadiene/chloroprene (BR/CR) nanocomposites 3 phr MLG replaced 15 phr CB and/or 3 phr ATH. Material and mechanical properties as well as fire behavior of the nanocomposites are compared to BR/CR with 20 phr CB both with and without 50 phr ATH. MLG appears as a promising nanofiller to improve the functional properties: replacement of CB improved rheological, curing, and mechanical properties; substitution of ATH improved nanocomposite properties without affecting flame retardancy. KW - Nanocomposites KW - Rubber KW - Multilayer graphene KW - Carbon black KW - Polybutadiene/chloroprene KW - Graphene PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523468 DO - https://doi.org/10.1515/epoly-2021-0026 SN - 1618-7229 VL - 21 IS - 1 SP - 244 EP - 262 PB - De Gruyter AN - OPUS4-52346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Diercks, Philipp A1 - Veroy, K. A1 - Robens-Radermacher, Annika A1 - Unger, Jörg F. T1 - Multiscale modeling of linear elastic heterogeneous structures via localized model order reduction N2 - In this paper, a methodology for fine scale modeling of large scale linear elastic structures is proposed, which combines the variational multiscale method, domain decomposition and model order reduction. The influence of the fine scale on the coarse scale is modelled by the use of an additive split of the displacement field, addressing applications without a clear scale separation. Local reduced spaces are constructed by solving an oversampling problem with random boundary conditions. Herein, we inform the boundary conditions by a global reduced problem and compare our approach using physically meaningful correlated samples with existing approaches using uncorrelated samples. The local spaces are designed such that the local contribution of each subdomain can be coupled in a conforming way, which also preserves the sparsity pattern of standard finite element assembly procedures. Several numerical experiments show the accuracy and efficiency of the method, as well as its potential to reduce the size of the local spaces and the number of training samples compared to the uncorrelated sampling. KW - Multiscale methods KW - Variational multiscale method KW - Localized model order reduction KW - Domain decomposition methods PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580671 DO - https://doi.org/10.1002/nme.7326 SN - 0029-5981 SP - 1 EP - 23 PB - Wiley online library AN - OPUS4-58067 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zinas, Orestis A1 - Papaioannou, Iason A1 - Schneider, Ronald A1 - Cuéllar, Pablo T1 - Multivariate Gaussian Process Regression for 3D site characterization from CPT and categorical borehole data N2 - Accurate prediction of subsurface stratigraphy and geotechnical properties, along with quantification of associated uncertainties, is essential for improving the design and assessment of geotechnical structures. Several studies have utilized indirect data from Cone Penetration Tests (CPTs) and employed statistical and Machine Learning methods to quantify the geological and geotechnical uncertainty. Incorporating direct borehole data can reduce uncertainties. This study proposes a computationally efficient multivariate Gaussian Process model that utilizes site-specific data and: (i) jointly models multiple categorical (USCS labels) and continuous CPT variables, (ii) learns a non-separable covariance structure leveraging the Linear Model of Coregionalization, and (iii) predicts a USCS based stratigraphy and CPT parameters at any location within the 3D domain. The results demonstrate that integrating geotechnical and geological data into a unified model yields more reliable predictions of subsurface stratification, enabling the parallel interpretation of both USCS classification and CPT profiles. Importantly, the model demonstrates its potential to integrate multiple variables from different sources and data types, contributing to the advancement of methodologies for the joint modeling of geotechnical, geological, and geophysical data. KW - Geotechnical site-characterization KW - Cone Penetration Tests KW - Stratigraphy prediction KW - Multivariate Gaussian process KW - Variational inference KW - Linear Model of Coregionalization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-629456 DO - https://doi.org/10.1016/j.enggeo.2025.108052 SN - 1872-6917 VL - 352 SP - 1 EP - 19 PB - Elsevier B.V. AN - OPUS4-62945 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sano, Silvia Di A1 - Costa, Giancarlo A1 - Giordano, Pier Francesco A1 - Pregnolato, Maria A1 - Limongelli, Maria Pina T1 - Multi‐risk assessment for bridges: The application of the Italian Guidelines N2 - Bridges are essential elements in the built environment since they underpin the functioning of transportation systems. Nevertheless, they are vulnerable due to aggressive environment, demand beyond the design level, and other contingencies such as extreme events. The management of bridges represents a significant challenge for improving transport performance and ensure the safety of users. In Italy, bridge management is addressed by the recent “Guidelines for risk classification and management, safety evaluation and monitoring of existing bridges” which were issued by the Italian Ministry for Public Work in 2020. The guidelines propose an operational approach with distinctive characteristics: (i) risk‐based, i.e., based on the typical parameters of hazard, vulnerability, and exposure; (ii) multi‐level, i.e., they include six assessment levels (0‐5) of increasing complexity; and (iii) multi‐risk, i.e., they assess structural/foundation, seismic, hydrological and landslide risk. This paper presents a general overview of the 2020 Italian Guidelines and their application to a selected case study. Lessons from the application to the case study are drafted and possible criticalities highlighted. KW - Bridge management KW - Infrastructures KW - Italian guidelines KW - Structural safety KW - Risk assessment KW - Risk classification PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653392 DO - https://doi.org/10.1002/cepa.2046 SN - 2509-7075 VL - 6 IS - 5 SP - 772 EP - 779 PB - Wiley CY - Berlin AN - OPUS4-65339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strommer, Bettina A1 - Schulze, Dietmar A1 - Schartel, Bernhard A1 - Böhning, Martin T1 - Networking Skills: The Effect of Graphene on the Crosslinking of Natural Rubber Nanocomposites with Sulfur and Peroxide Systems N2 - Tailored crosslinking in elastomers is crucial for their technical applications. The incorporation of nanoparticles with high surface-to-volume ratios not only leads to the formation of physical networks and influences the ultimate performance of nanocomposites, but it also affects the chemical crosslinking reactions. The influence of few-layer graphene (FLG) on the crosslinking behavior of natural rubber is investigated. Four different curing systems, two sulfur-based with different accelerator-to-sulfur ratios, and two peroxide-based with different peroxide concentrations, are combined with different FLG contents. Using differential scanning calorimetry (DSC), vulcametry (MDR) and swelling measurements, the results show an accelerating effect of FLG on the kinetics of the sulfur-based curing systems, with an exothermic reaction peak in DSC shifted to lower temperatures and lower scorch and curing times in the MDR. While a higher accelerator-to-sulfur ratio in combination with FLG leads to reduced crosslinking densities, the peroxide crosslinkers are hardly affected by the presence of FLG. The good agreement of crosslink densities obtained from the swelling behavior confirms the suitability of vulcameter measurements for monitoring the complex vulcanization process of such nanocomposite systems in a simple and efficient way. The reinforcing effect of FLG shows the highest relative improvements in weakly crosslinked nanocomposites. KW - Nanocomposite KW - Elastomers KW - Graphene KW - Crosslinking KW - Network KW - Rubber KW - Vulcanization PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-560409 DO - https://doi.org/10.3390/polym14204363 VL - 14 IS - 20 PB - MDPI AN - OPUS4-56040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nandish, Ranjith A1 - Knaust, Christian A1 - Zehfuß, Jochen T1 - Numerical Investigations of a Large Fire Exposure Crib Test—Presenting Different Pyrolysis Modelling Methodologies and Numerical Results N2 - ABSTRACTThe need for numerical‐based approaches to investigate the fire behaviour in buildings with combustible components is growing due to the increasing use of timber by the construction industry to meet the ‘Climate Action Plan 2050’. This requires consideration of the complex kinetic processes that take place during the burning of the wood in the numerical models. This is accomplished by using computational fluid dynamics (CFD) to numerically model the material pyrolysis and combustion processes. This article presents three different approaches for simulating the behaviour of a wood crib fire using the fire dynamics simulator (FDS). These approaches are based on either prescribing the burning rate of the wood directly from the physical experiments or using the kinetic parameters to govern the underlying processes, such as pyrolysis. Wooden crib fire experiments carried out by the RISE Research Institute in Sweden inside the combustion chamber that were used to validate all the methods. The numerical results from the method, that utilised the experimentally determined burning rate, were in good agreement with the experimental results, with a maximum deviation of 6% in the case of HRR. On the other hand, the model that needs kinetic parameters as its input has shown maximum discrepancies of 12% and 33% compared to experimental results. These methods are sensitive to the input parameters and the extent of dependency needs further investigation. KW - Pyrolysis KW - Wood combustion KW - Wood fire loads KW - Wooden buildings PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626567 DO - https://doi.org/10.1002/fam.3287 SN - 1099-1018 VL - 49 IS - 4 SP - 371 EP - 387 PB - John Wiley & Sons Ltd. AN - OPUS4-62656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ebell, Gino A1 - Tannert, S. A1 - Lehmann, Jens A1 - Müller, H. T1 - Offshore Weathering Campaign on a North Sea Wind Farm Part One: Corrosivity Categories N2 - The aim of this study is to investigate the corrosion behavior of materials and coatings in offshore environments, with a focus on determining the corrosivity categories at different locations on wind turbines. The collaboration between the authors enabled a 3‐year weathering campaign at the Hohe See and Albatros offshore wind farms in the North Sea. Metal panels were installed on two wind turbines to assess the corrosivity of different atmospheric conditions. Preliminary results indicate significant variations in corrosivity depending on location and material used, suggesting that current standards may not fully reflect real‐world conditions. The results of the study will help to optimize material selection and corrosion protection strategies for offshore wind farms, potentially extending their lifetime and reducing operating costs. KW - Corrosion KW - Offshore KW - Wind PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-628995 DO - https://doi.org/10.1002/maco.202414711 SN - 1521-4176 SP - 1 EP - 10 PB - Wiley CY - Weinheim AN - OPUS4-62899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rudić, O. A1 - Mittermayr, F. A1 - Gluth, Gregor A1 - Simon, Sebastian A1 - Ukrainczyk, N. A1 - Seyrek, Y. A1 - Freytag, B. A1 - Juhart, J. A1 - Grengg, C. T1 - On the benefits of vegetable oil addition for the pore structure and acid resistance of alkali-activated systems N2 - The impact of high additions of vegetable oil (12 vol%) on the mechanical and microstructural properties of metakaolin-slag-based alkali-activated materials (AAMs) was studied. The addition of oil resulted in a slight decrease in initial polymerization kinetics but did not affect the final degree of reaction. AAM-oil-composite-mortars exhibited approximately ∼30% lower compressive strength primarily due to the entrainment of air voids. Newly formed soap phases significantly reduced the volume of small capillary and gel pores (pore radii <15 nm), leading to a decrease in specific inner surface area by a factor of up to 15. The porosity modification induced by the oil addition greatly enhanced the resistance of AAMs against sulfuric acid attack, shifting the dominant processes from diffusion and cracks to framework-dissolution controlled by the inherent phase stabilities. Following the immersion in sulfuric acid (pHstat = 2) for 8 weeks, the depth of corroded layer decreased by 70% and no cracks due to expansive phases were observed. These promising findings suggest that the incorporation of vegetable oil in AAMs has the potential to address durability concerns associated with diffusion-based corrosion processes, thereby expanding the range of future applications. KW - Alkali-activated materials KW - Acid resistance KW - Pore structure PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581719 DO - https://doi.org/10.1016/j.ceramint.2023.08.036 VL - 49 IS - 20 SP - 33275 EP - 33290 PB - Elsevier Ltd. AN - OPUS4-58171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Asante, Bright T1 - Optimized mix design and fire resistance of geopolymer recycled aggregate concrete under elevated temperatures N2 - This study investigates the performance of fly ash-based geopolymer recycled aggregate concrete (GRAC) as a sustainable alternative to Ordinary Portland Cement (OPC) concrete, focusing on its compressive strength and behavior under high-temperature exposure (150 ◦C, 300 ◦C, 600 ◦C, and 900 ◦C). The research emphasizes the use of 100 % recycled concrete aggregates as a replacement for natural aggregates, with samples cured at ambient conditions and at 60 ◦C in an oven. Key factors, including water content and curing conditions, were evaluated to determine their influence on compressive strength and thermal stability. Results indicate that water content is the primary factor governing compressive strength, while recycled aggregates contribute to a secondary but notable effect. GRAC maintained up to 65 % of its initial strength after exposure to 600 ◦C, though strength degradation and severe cracking occurred at 900 ◦C. Oven-cured samples showed fewer surface cracks but experienced slightly higher mass loss than room-cured coun-terparts. This study highlights the potential of GRAC as an environmentally friendly material capable of withstanding moderate thermal conditions, providing significant contributions to green construction practices and the reuse of construction and demolition waste. KW - Geopolymer KW - Recycled aggregate concrete KW - Elevated temperature PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-627071 DO - https://doi.org/10.1016/j.cscm.2025.e04401 SN - 2214-5095 VL - 22 SP - 1 EP - 17 PB - Elsevier Ltd. AN - OPUS4-62707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Patrick A1 - Schneider, Ronald A1 - Baeßler, Matthias A1 - Morgenthal, Guido T1 - Parallelized adaptive Bayesian updating with structural reliability methods for inference of large engineering models N2 - The reassessment of engineering structures, such as bridges, now increasingly involve the integration of models with realworld data. This integration aims to achieve accurate ‘as-is’ analysis within a digital twin framework. Bayesian model updating combines prior knowledge and data with models to enhance the modelling accuracy while consistently handling uncertainties. When updating large engineering models, numerical methods for Bayesian analysis present significant computational challenges due to the need for a substantial number of likelihood evaluations. The novelty of this contribution is to parallelize adaptive Bayesian Updating with Structural reliability methods combined with subset simulation (aBUS) to improve its computational efficiency. To demonstrate the efficiency and practical applicability of the proposed approach, we present a case study on the Maintalbrücke Gemünden, a large railway bridge. We leverage modal property data to update a linear-elastic dynamic structural model of the bridge. The parallelized aBUS approach significantly reduces computational time, making Bayesian updating of large engineering models feasible within reasonable timeframes. The improved efficiency allows for a wider implementation of Bayesian model updating in structural health monitoring and maintenance decision support systems. KW - Bayesian model updating KW - Bayesian updating with structural reliability methods KW - Structural health monitoring KW - Parallelization KW - Modal analysis KW - Railway bridge PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-633686 DO - https://doi.org/10.1177/13694332251346848 SN - 1369-4332 SN - 2048-4011 SP - 1 EP - 26 PB - Sage AN - OPUS4-63368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tomiak, F. A1 - Schartel, Bernhard A1 - Wolf, M. A1 - Drummer, D. T1 - Particle Size Related Effects of Multi-Component Flame-Retardant Systems in poly(butadiene terephthalate) N2 - Aluminum tris (diethylphosphinate) (AlPi) is known to have an efficient flame-retardant effect when used in poly(butadiene terephthalates) (PBT). Additionally, better flame-retardant effects can be achieved through the partial substitution of AlPi by boehmite in multi-component systems, which have been shown to be an effective synergist due to cooling effects and residue formation. Although the potential of beneficial effects is generally well known, the influence of particle sizes and behavior in synergistic compositions are still unknown. Within this paper, it is shown that the synergistic effects in flammability measured by limiting oxygen index (LOI) can vary depending on the particle size distribution used in PBT. In conducting thermogravimetric analysis (TGA) measurements, it was observed that smaller boehmite particles result in slightly increased char yields, most probably due to increased reactivity of the metal oxides formed, and they react slightly earlier than larger boehmite particles. This leads to an earlier release of water into the system enhancing the hydrolysis of PBT. Supported by Fourier transformation infrared spectroscopy (FTIR), we propose that the later reactions of the larger boehmite particles decrease the portion of highly flammable tetrahydrofuran in the gas phase within early burning stages. Therefore, the LOI index increased by 4 vol.% when lager boehmite particles were used for the synergistic mixture. KW - Flame retardants KW - Aluminum diethylphosphinate KW - Boehmite KW - Poly(butadiene terephthalates) (PBT) KW - Mechanical properties PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509286 DO - https://doi.org/10.3390/polym12061315 SN - 2073-4360 VL - 12 IS - 6 SP - 1315 PB - MDPI AN - OPUS4-50928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Häßler, Dustin A1 - Hothan, Sascha T1 - Performance of intumescent fire protection coatings applied to structural steel tension members with circular solid and hollow sections N2 - Intumescent fire protection coatings are used to improve the fire resistance of steel members. Due to slender cross-sections typically used for tension members, high demands are placed on the effectiveness and reliability of the intumescent coatings. This paper describes real-scale fire tests of intumescent coatings applied to steel tension members with circular solid and hollow sections. First, the current regulations for the application of intumescent coatings on steel tension members are discussed. After that, a comparison between the foaming behaviour and failure mechanisms of intumescent coatings applied to steel tension members with different cross-sections and loading conditions is given. Next, the experimental setup and procedure of the performed fire tests are presented. In addition, the influences of various parameters on the performance of the intumescent coating are analysed, including the geometry of the steel profile, dry film thickness of the intumescent coating, load utilisation level as well as the orientation of the member. Based on the theoretical considerations and results of the fire tests, it is evidenced that mechanically loaded fire tests are essential to assess accurately the contribution of intumescent fire protection coatings to the fire resistance of steel tension members with circular solid sections. KW - Fire tests KW - Intumescent coating KW - Reactive fire protection system KW - Steel KW - Tension members PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548981 DO - https://doi.org/10.1016/j.firesaf.2022.103605 SN - 0379-7112 VL - 131 SP - 1 EP - 12 PB - Elsevier Ltd. AN - OPUS4-54898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiedeitz, M. A1 - Schmidt, Wolfram A1 - Härder, M. A1 - Kränkel, T. T1 - Performance of rice husk ash as supplementary cementitious material after production in the field and in the lab N2 - Supplementary cementitious materials (SCM) can reduce the total amount of Portland cement clinker in concrete production. Rice husk ashes (RHA) can be converted from an agricultural by-product to a high-performance concrete constituent due to a high amount of reactive silica with pozzolanic properties if they are burnt under controlled conditions. The way and duration of combustion, the cooling process as well as the temperature have an effect on the silica form and thus, the chemical and physical performance of the RHA. Various studies on the best combustion technique have been published to investigate the ideal combustion techniques. Yet, the process mostly took place under laboratory conditions. Investigating the difference between the performance of RHA produced in a rural environment and laboratory conditions is useful for the assessment and future enhancement of RHA production, and its application both as building material, for example in rural areas where it is sourced in large quantities, and as additive for high performance concrete. Thus, the paper presents a comparison between RHA produced under rudimentary conditions in a self-made furnace in the rural Bagamoyo, Tanzania and under controlled laboratory conditions at the Technical University of Munich, Germany, with different combustion methods and temperatures. In a second step, RHA was ground to reach particle size distributions comparable to cement. In a third step, cement pastes were prepared with 10%, 20% and 40% of cement replacement, and compared to the performance of plain and fly ash blended cement pastes. The results show that controlled burning conditions around 650 °C lead to high reactivity of silica and, therefore, to good performance as SCM. However, also the RHA burnt under less controlled conditions in the field provided reasonably good properties, if the process took place with proper burning parameters and adequate grinding. The knowledge can be implemented in the field to improve the final RHA performance as SCM in concrete. KW - Rice husk ash KW - Agricultural by-product KW - Supplementary cementitious material KW - Waste management KW - Carbon dioxide emissions PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568953 DO - https://doi.org/10.3390/ma13194319 SN - 1996-1944 VL - 13 SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-56895 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strobl, Dominic A1 - Unger, Jörg F. A1 - Ghnatios, C. A1 - Robens-Radermacher, Annika T1 - PGD in thermal transient problems with a moving heat source: A sensitivity study on factors affecting accuracy and efficiency N2 - Thermal transient problems, essential for modeling applications like welding and additive metal manufacturing, are characterized by a dynamic evolution of temperature. Accurately simulating these phenomena is often computationally expensive, thus limiting their applications, for example for model parameter estimation or online process control. Model order reduction, a solution to preserve the accuracy while reducing the computation time, is explored. This article addresses challenges in developing reduced order models using the proper generalized decomposition (PGD) for transient thermal problems with a specific treatment of the moving heat source within the reduced model. Factors affecting accuracy, convergence, and computational cost, such as discretization methods (finite element and finite difference), a dimensionless formulation, the size of the heat source, and the inclusion of material parameters as additional PGD variables are examined across progressively complex examples. The results demonstrate the influence of these factors on the PGD model’s performance and emphasize the importance of their consideration when implementing such models. For thermal example, it is demonstrated that a PGD model with a finite difference discretization in time, a dimensionless representation, a mapping for a moving heat source, and a spatial domain non-separation yields the best approximation to the full order model. KW - Additive manufacturing KW - Mapping for unseparable load KW - Model order reduction (MOR) KW - Thermal transient problem KW - Sensitivity analysis KW - Proper generalized decomposition (PGD) PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598001 DO - https://doi.org/10.1002/eng2.12887 VL - 6 IS - 11 SP - 1 EP - 22 PB - John Wiley & Sons Ltd. CY - Berlin AN - OPUS4-59800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Kleinbub, Sherin A1 - Wachtendorf, Volker A1 - Schütter, Jan David A1 - Niebergall, Ute A1 - Böhning, Martin A1 - Koerdt, Andrea T1 - Photo-oxidation of PE-HD affecting polymer/fuel interaction and bacterial attachment N2 - In the present study, a simple approach was used to investigate the effect of UV-exposure on two high density Polyethylene materials (PE-HD), commonly used for storage tanks, on fuel sorption behavior and colonization by microorganisms. The aim was to investigate whether the sorption behavior of the fuels (diesel/biodiesel) and the colonization by microorganisms, frequently occurring in the fuel, is affected and may lead to undesirable or safety-relevant material changes. We showed that the UV-irradiation leads to significant changes of the sorption behavior due to chemi-crystallization and crosslinking. The fuel Sorption is affected by the UV-induced formation of polar carbonyl and hydroxyl groups predominantly occurring at the surface. With respect to microbial colonization behavior for Bacillus subtilis and Pseudomonas aeruginosa, isolated from a contaminated diesel sample, differences of the initial adhesion could be shown depending on the initial type of polyethylene as well as on the degree of UV-induced degradation. KW - High density polyethylene KW - Bacterial attachment KW - UV-irradiation KW - Fuel sorption PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510001 DO - https://doi.org/10.1038/s41529-020-0122-1 VL - 4 IS - 1 SP - Article number: 18 PB - Nature Partner Journals AN - OPUS4-51000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Salari, Farid A1 - Zocca, Andrea A1 - Bosetti, Paolo A1 - Hlaváček, Petr A1 - Italiano, Antonino A1 - Gobbin, Filippo A1 - Colombo, Paolo A1 - Kühne, Hans-Carsten A1 - Sglavo, Vincenzo M. T1 - Powder-bed 3D printing by selective activation of magnesium phosphate cement: Determining significant processing parameters and their effect on mechanical strength N2 - The present work addresses powder bed binder jetting additive manufacturing by selective magnesium phosphate cement activation. Despite the potential of this technology to aid the digitalization of the construction industry, the effect of processing parameters on the mechanical performance of printed materials has not yet been studied to generate a guideline for the further development of the technology. Statistical methodologies were used to screen the effect of four printing process parameters (printing speed, layer thickness, raster angle, and build direction on flexural and compressive strength). As the exploited technology works with constant fluid pressure, the physical interpretation of the effect of each factor can be considered taking into account the interactions between the binder materials in the powder bed. Analysis of variance (ANOVA) indicated that printing speed and layer thickness significantly affect mechanical performances. Furthermore, the layout of samples for the printing process is preferable to be parallel the printhead movement. An anisotropic behavior was observed, and the samples subjected to compressive forces parallel to the layer plane possessed lower strength values. This effect can be interpreted as a result of a weak area of low density in between layers, leading to a pronounced delamination under compression. Even though the strength of the printed material is not suitable for a structural concrete, it can be marginally improved by design of experiment and optimized for non-structural applications, such as for porous artificial stone. Design of experiment coupled with ANOVA methods can be used in the future to support the development of novel material mixtures, thus expanding the fields of application of this novel additive manufacturing technology. KW - Concrete 3D-printing KW - Particle-bed binder jetting KW - Design of experiment PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601654 DO - https://doi.org/10.1016/j.oceram.2024.100609 VL - 18 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-60165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fornacon-Wood, C. A1 - Stühler, M. R. A1 - Gallizioli, C. A1 - Manjunatha, B. R. A1 - Wachtendorf, Volker A1 - Schartel, Bernhard A1 - Plajer, A. J. T1 - Precise construction of weather-sensitive poly(ester-alt-thioesters) from phthalic thioanhydride and oxetane N2 - We report the selective ring opening copolymerisation (ROCOP) of oxetane and phthalic thioanhydride by a heterobimetallic Cr(III)K catalyst precisely yielding semi-crystalline alternating poly(esteralt- thioesters) which show improved degradability due to the thioester links in the polymer backbone. KW - Sulfur containing polymers KW - Durability KW - Weathering KW - Synthesis PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-590762 DO - https://doi.org/10.1039/d3cc03315e SN - 1364-548X VL - 59 IS - 76 SP - 11353 EP - 11356 PB - RSC AN - OPUS4-59076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koniorczyk, M. A1 - Bednarska, Dalia A1 - Wieczorek, A. A1 - Materak, K. T1 - Probabilistic approach to concrete durability based on combined stochastic differential equations and Monte Carlo method N2 - Cementitious materials are often exposed to aggressive environments, which have a significant impact on their durability. Proper prediction of concrete corrosion helps to apply the right measures and technologies, to extend the service life of structures. Carbonation and cyclic freezing are recognized among the most common corrosive factors for concrete. Their progress is linked to the penetration of CO2 and water into the concrete structure. Due to the random arrangement of aggregates and cement paste, concrete is an inhomogeneous material. Therefore, the progress of carbonation and frost-induced damage should be treated as random variables with appropriate probabilistic parameters. Experimental studies on concrete carbonation and freezing were conducted in accordance with the standards EN 12390–12 and EN 12390–9. As observed in the experiments, the progress of carbonation and frost damage of concrete could be described by zigzag, not necessarily monotonic functions. Stochastic differential equations (SDE) were employed to predict the behavior of concrete exposed to elevated CO2 concentrations and cyclic freezing. The stochastic model consisted of a drift term, which described the general trend of concrete durability exposed to carbonation and frost cycles, as well as a diffusion term, which accounted for the stochastic features of inhomogeneous concrete microstructure. The Euler–Maruyama approximation with Milstein improvement was applied to model the realization of the stochastic changes in concrete microstructure/durability. The proposed approach predicted experimental results with high accuracy. The application of the Monte Carlo (MC) method with 100,000 SDE realizations allowed to calculate the statistical parameters of the processes, such as concrete carbonation and freezing cycles. The probabilistic parameters, such as expected values and standard deviations, calculated using the SDE_MC approach, were in good agreement with experimental results for both problems, i.e. decelerating concrete carbonation and accelerating concrete scaling. KW - Concrete durability KW - Concrete carbonation KW - Concrete scaling KW - Time-dependent random variable KW - Stochastic differential equations PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643417 DO - https://doi.org/10.1007/s43452-025-01335-y SN - 2083-3318 VL - 25 IS - 5-6 SP - 1 EP - 31 PB - Springer Nature Switzerland AG CY - Schweiz AN - OPUS4-64341 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Farhan, Muhammad A1 - Schneider, Ronald A1 - Thöns, Sebastian A1 - Gündel, M. T1 - Probabilistic cost modeling as a basis for optimizing inspection and maintenance of turbine support structures in offshore wind farms N2 - The operational management of offshore wind farms includes inspection and maintenance (I&M) of the wind turbine support structures. These activities are complex and influenced by numerous uncertain factors that affect their costs. The uncertainty in the I&M costs should be considered in decision value analyses performed to optimize I&M strategies for the turbine support structures. In this paper, we formulate a probabilistic parametric model to describe I&M costs for the common case in which a wind farm is serviced and maintained using a workboat-based strategy. The model is developed based on (a) interviews with a wind farm operator, engineering consultants, and operation and maintenance engineers, as well as (b) scientific literature. Our methodology involves deriving the probabilistic models of the cost model parameters based on intervals representing a subjective expert opinion on the foreseeable ranges of the parameter values. The probabilistic cost model is applied to evaluate the total I&M costs, and a sensitivity analysis is conducted to identify the main cost drivers. The model can be utilized to optimize I&M strategies at the component, structural system, and wind farm level. To illustrate its potential use, we apply it in a numerical study in which we optimize I&M strategies at the structural system level and identify and demonstrate a simplified approach of capturing uncertain I&M costs in the optimization. The simplified approach is generalized and made available for maintenance cost optimization of offshore wind turbine structures. KW - Inspection KW - Maintenance KW - Turbine support structures KW - Offshore wind KW - Costs PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626144 DO - https://doi.org/10.5194/wes-10-461-2025 SN - 2366-7443 SN - 2366-7451 VL - 10 IS - 2 SP - 461 EP - 481 PB - Copernicus Publications CY - Göttingen AN - OPUS4-62614 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Patrick A1 - Moye, J. A1 - Gluth, Gregor A1 - Vogler, Nico A1 - Taffe, A. A1 - Kühne, Hans-Carsten ED - Rossignol, S. ED - Gluth, Gregor T1 - Properties of alkali-activated mortars with salt aggregate for sealing structures in evaporite rock N2 - Concrete structures for sealing of tunnels in the host rock are an essential part of systems for nuclear waste storage. However, concretes based on blended cements or magnesium oxychloride cements, which are commonly considered for this application, can deteriorate severely due to a significant heat of hydration and associated deformation and cracking. Alkali-activated materials (AAMs) offer a potential solution to this problem because of their low heat release during hardening. To explore their suitability for the construction of sealing structures in evaporite rock, various AAMs with salt aggregate were studied regarding fresh properties, heat release, mechanical properties and microstructure. The heat of reaction of the AAMs was up to 55% lower than that of a blended cement designed for sealing structures, indicating significant benefits for the intended application. Other relevant properties such as mechanical strength and permeability depended strongly on the mix-design of the AAMs and curing conditions. KW - Alkali-activated materials KW - Geopolymers KW - Nuclear waste storage KW - Sealing structures KW - Evaporite rock PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519422 DO - https://doi.org/10.1016/j.oceram.2020.100041 SN - 2666-5395 VL - 5 IS - Special issue: Alkali-activated materials and geopolymers in ceramics and beyond SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-51942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kazlagić, Anera A1 - Vogl, Jochen A1 - Gluth, Gregor A1 - Stephan, D. T1 - Provenancing of cement using elemental analyses and isotope techniques – The state-of-the-art and future perspectives N2 - With the aim of identifying the origin and the manufacturer of a cement, a reliable procedure that provides unambiguous results is needed. Such procedure could resolve practical issues in damage research, liability issues and forensic investigations. A substantial number of attempts for fingerprinting of building materials, including cement, has already been carried out during the last decades. Most of them were based on concentration analysis of the main elements/components. This review provides an overview of provenance studies of cement and the main approaches commonly used. Provenance studies of cement via isotope techniques are also presented and discussed as representatives of the state-of-the-art in the field. Due to the characteristic properties and the occurrence of carefully selected isotope ratios, unique fingerprints of different kinds of materials can be provided by these methods. This property has largely been explored in various scientific fields such as geo- and cosmochemistry, food forensics, archaeology, geochronology, biomedical studies, and climate change processes. However, the potential of isotope techniques in cement and concrete research for provenance studies has barely been investigated. Therefore, the review outlines a suitable approach using isotope ratios, which could lead to reliable provenancing of cementitious materials in the future. KW - Cement KW - Sr isotopes KW - Provenance PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-533762 DO - https://doi.org/10.1039/d1ja00144b VL - 36 IS - 10 SP - 2030 EP - 2042 PB - The Royal Society of Chemistry CY - Cambridge, UK AN - OPUS4-53376 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sigrüner, M. A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Herz, J. A1 - Muscat, D. A1 - Strübbe, N. T1 - Pull-out behavior of polymer fibers in concrete N2 - The bond between polymer fibers and the surrounding cementitious matrix is essential for the development of concrete reinforcement. The single fiber pull-out test (SFPT) is the standard characterization technique for testing the bond strength. However, the different phases of debonding cannot be distinguished by the SFPT. This study investigates the debonding of different polymer fibers from the surrounding cementitious matrix with a modified SFPT and proposes methods to change the SFPT setup to generate more valuable information on the debonding mechanism. The SFPT was equipped with linear variable differential transformers (LVDT), digital image correlation (DIC) and acoustic emission (AE) analysis. The results demonstrate that the modified SFPT allows a better understanding of the different phases of debonding during fiber pull-out. Furthermore, bond strength values calculated by different methods reveal that the chemical bond of the investigated polymers is not different as reported by previous studies. Deformation measurements performed using LVDTs and DIC are suitable measuring techniques to characterize the debonding mechanism in SFPT. A correlation between recorded AE and debonding phases was not found. KW - Polymer Fibres KW - Concrete KW - Pull-Out Behaviour KW - Debonding Mechanism PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582918 DO - https://doi.org/10.1002/pol.20230264 SN - 2642-4169 SP - 1 EP - 13 PB - Wiley Periodicals, LLC. AN - OPUS4-58291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bibinger, J. A1 - Eibl, S. A1 - Gudladt, H.-J. A1 - Schartel, Bernhard A1 - Höfer, P. T1 - Pushing the limits of thermal resistance in nanocomposites: A comparative study of carbon black and nanotube modifications N2 - Enhancing the thermal resistance of carbon fiber-reinforced polymers (CFRPs) with flame retardants or coatings often leads to increased weight and reduced mechanical integrity. To address these challenges, this study introduces an innovative approach for developing nanocomposites using carbon-based nanoparticles, while preserving the structural lightweight properties. For this, carbon black particles (CBPs) up to 10% and carbon nanotubes (CNTs) up to 1.5% were incorporated into the RTM6/G939 composite material. The obtained samples were then analyzed for their properties and heat resistance under one-sided thermal loading at a heat flux of 50 kW/m2. Results demonstrate that integrating these particles improves heat conduction without compromising the material’s inherent advantages. As a result, thermo-induced damage and the resulting loss of mechanical strength are delayed by 17% with CBPs and 7% with CNTs compared to the unmodified material. Thereby, the thermal behavior can be accurately modeled by a straightforward approach, using calibrated, effective measurements of the nanoparticles in the polymer matrix rather than relying on theoretical assumptions. This approach thus provides a promising methode to characterize and improve thermal resistance without significant trade-offs. KW - Nanomaterial KW - Cabon fiber-reinforced polymer (CFRP) KW - Carbon black (CB) KW - Carbon nanotube (CNT) KW - Improving heat conduction KW - Prediction thermal properties PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-628632 DO - https://doi.org/10.3390/nano15070546 SN - 2079-4991 VL - 15 IS - 7 SP - 1 EP - 23 PB - MDPI CY - Basel AN - OPUS4-62863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hupp, Vitus A1 - Schartel, Bernhard A1 - Flothmeier, K. A1 - Hartwig, A. T1 - Pyrolysis and flammability of phosphorus based flame retardant pressure sensitive adhesives and adhesive tapes N2 - Pressure-sensitive adhesive tapes are used in a variety of applications such as construction, aircrafts, railway vehicles, and ships, where flame retardancy is essential. Especially in these applications, phosphorus-based flame retardants are often chosen over halogenated ones due to their advantages in terms of toxicity. Although there are pressure-sensitive adhesives with phosphorus flame retardants available on the market, their flame-retardant modes of action and mechanisms are not entirely understood. This research article provides fundamental pyrolysis research of three phosphorus-based flame retardants that exhibit different mechanisms in a pressuresensitive adhesive matrix. The flame-retardants modes of action and mechanisms of a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivate, an aryl phosphate, and a self-synthesized, covalently bonded DOPO derivate (copolymerized) are investigated. The blended DOPO derivate is volatilized at rather low temperatures while the covalently bonded DOPO derivate decomposes together with the polymer matrix at the same temperature. Both DOPO derivates release PO radicals which are known for their flame inhibition. The aryl phosphate decomposes at higher temperatures, releases small amounts of aryl phosphates into the gas phase, and acts predominantly the condensed phase. The aryl phosphate acts as precursor for phosphoric acid and improves the charring of the pressure sensitive adhesive matrix. All flame retardants enhance the flammability of the adhesives depending on their individual mode of action while the covalently bonded flame retardant additionally improves the mechanical properties at elevated temperatures making it a promising future technology for pressure-sensitive adhesives. KW - Pyrolysis of flame retardant KW - Pyrolysis gas chromatography KW - Mass spectrometry KW - Phosphorus flame retardant KW - Decomposition mechanism KW - Flame retardant pressure sensitive adhesives KW - Flame retardancy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607192 DO - https://doi.org/10.1016/j.jaap.2024.106658 SN - 0165-2370 SN - 1873-250X VL - 181 SP - 1 EP - 31 PB - Elsevier B.V. AN - OPUS4-60719 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiehle, Philipp A1 - Härder, Michelle A1 - Strangfeld, Christoph T1 - Quantification of moisture content in earth block masonry under natural climatic conditions N2 - The aim of this study is to accurately predict the moisture content in earth block masonry exposed to natural climatic conditions, which is a key factor in assessing its load-bearing capacity. Nuclear magnetic resonance relaxometry and humidity sensor measurements were carried out to quantify the moisture content. In addition, a customised test setup was developed to determine the capillary water absorption of earth blocks. This approach takes into account the deceleration of water absorption due to the swelling of clay minerals and organic additives, which leads to realistic transport coefficients in the hygroscopic range. This allows the moisture content of earth block masonry to be predicted accurately. With regard to the moisture behaviour of typical exterior wall constructions in living spaces, it was found that the equilibrium moisture content in earth block masonry is always lower than 65 % relative humidity, which corresponds to the permissible limit of the recently published German design standard for load-bearing earth block masonry. KW - Earth block masonry KW - NMR relaxometry KW - Hygrothermal simulation KW - Load-bearing capacity KW - Moisture content KW - Embedded humidity sensors PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623518 DO - https://doi.org/10.1016/j.conbuildmat.2024.139513 VL - 459 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-62351 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Colmenares, Daniel A1 - Costa, Giancarlo A1 - Civera, Marco A1 - Surace, Cecilia A1 - Karoumi, Raid T1 - Quantification of the human–structure interaction effect through full-scale dynamic testing: The Folke Bernadotte Bridge N2 - An analytical expression for the frequency response function of a coupled pedestrian-bridge system is presented and evaluated using an experimental measurement campaign performed on the Folke Bernadotte Bridge in Stockholm, Sweden. A finite element model and the modal models that consider the human–structure interaction effect are calibrated with respect to the measurements. The properties of the spring–mass–damper model representing the pedestrians were identified, considering the different structural modes of the system. Good agreement was obtained between the experimental and theoretical frequency response functions. A sensitivity analysis of the obtained solution was performed, validating the determined analytical expression for the frequency response function of the coupled pedestrian-bridge system that takes into account the human–structure interaction effect. KW - Safety KW - Building and Construction KW - Architecture KW - Civil and Structural Engineering KW - Risk KW - Reliability KW - Quality PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584038 DO - https://doi.org/10.1016/j.istruc.2023.06.133 SN - 2352-0124 VL - 55 SP - 2249 EP - 2265 PB - Elsevier AN - OPUS4-58403 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klippel, A. A1 - Hofmann-Böllinghaus, Anja A1 - Gnutzmann, Tanja A1 - Piechnik, K. T1 - Reaction-to-fire testing of bus interior materials: Assessing burning behaviour and smoke gas toxicity N2 - Although fire safety regulations for buses have been adapted in recent years regarding, for example, fire detection and engine fire suppression systems, the changes in regulations for bus interior materials are minimal. A comparison of fire safety regulations for interior materials in other transport sectors for trains, ships or aircraft reveals a much lower level of requirements for bus materials. Although repeated bus accidents as well as fire statistics show the danger a bus fire can pose to passengers. In particular, the combination of a fire incident and passengers with reduced mobility led to severe disasters in Germany and other European countries. To enhance the fire safety for passengers, the interior bus materials are crucial as the fire development in the bus cabin determines whether escape and rescue is possible. Against this background, bus interior materials were tested in different fire test scenarios. Measurement of a wide variety of parameters, for example, the mass loss, ignition time, smoke gas composition, heat release rate among others were carried out. Tested materials complied to the newest set of requirements. For this purpose, interior materials and their components had to be identified according to their chemical structure. Parts of the tests were funded by BASt (Federal Highway Research Institute) in the project 82.0723/2018. Experimental results show reaction-to-fire behaviour which lead to very limited times for escape and rescue in case of fire in a bus cabin. Based on the studies on fire behaviour and toxicity assessment, recommendations for improved fire safety regulations for interior materials could be made. KW - Burning behaviour KW - Bus interior materials KW - Cone calorimeter KW - DIN tube furnace KW - FTIR spectroscopy KW - Reference values KW - Smoke toxicity PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-576085 DO - https://doi.org/10.1002/fam.3108 SN - 1099-1018 VL - 47 IS - 5 SP - 665 EP - 680 PB - Wiley CY - New York, NY AN - OPUS4-57608 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schnell, A. A1 - Rübner, Katrin A1 - Seher, Julia A1 - Müller, A. A1 - Liebezeit, S. A1 - Fenner, J. A1 - Martin, F. A1 - Pniok, N. T1 - REALight ‐ Leichtgranulate und REA‐Gips aus feinkörnigen sulfatbelasteten Bau‐ und Abbruchabfällen N2 - Ziel des Projekts REALight ist die Entwicklung einer Referenzanlage zur Herstellung von Leichtgranulaten (leichte Gesteinskörnungen) aus Bau‐ und Abbruchabfällen und zur Gipsrückgewinnung. Als Rohstoffe werden bisher ungenutzte oder auf niedrigem Niveau eingesetzte Bau‐ und Abbruchabfälle und industrielle Nebenprodukte verwendet. Als Produkte werden leichte Gesteinskörnungen hergestellt. Die Sulfatabtrennung durch eine thermische Zersetzung bildet die Grundlage für die zusätzliche Gewinnung von Rauchgasentschwefelungs‐Gips (REA‐Gips). Das Projekt wird im Rahmen der Fördermaßnahme „Ressourceneffiziente Kreislaufwirtschaft – Bauen und Mineralische Stoffkreisläufe (ReMin)” gefördert. ReMin ist eine Maßnahme zur Umsetzung des BMBF‐Forschungskonzepts „Ressourceneffiziente Kreislaufwirtschaft” als Teil der BMBF Strategie „Forschung für nachhaltige Entwicklung – FONA”. Ziel der Förderung ist es, den Ausbau der Kreislaufwirtschaft voranzutreiben. Im Mittelpunkt steht dabei die Bauwirtschaft mit ihrer hohen Nachfrage nach Rohstoffen und gleichzeitig großen Mengen an anfallenden mineralischen Abfällen. Am Projekt REALight sind 12 Partner aus verschiedenen Bereichen der Baustoffherstellung und ‐anwendung, Abfallaufbereitung, Verfahrenstechnik sowie Forschung und Entwicklung beteiligt. T2 - 21. Internationale Baustofftagung (ibausil) CY - Weimar, Germany DA - 13.09.2023 KW - Baustoffrecycling KW - Leichtgranulate KW - Gips KW - Leichte Gesteinskörnungen KW - Drehrohrofen KW - Recycling KW - Mauerwerkbruch KW - Infraleichtbeton PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-591708 DO - https://doi.org/10.1002/cepa.2840 SN - 2509-7075 VL - 6 IS - 6 SP - 530 EP - 536 PB - Ernst & Sohn CY - Berlin AN - OPUS4-59170 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernal, S. A. A1 - Angst, U. M. A1 - Provis, J. L. A1 - Thiel, C. A1 - Gluth, Gregor A1 - Villagran-Zaccardi, Y. A1 - De Belie, N. T1 - Recommendation of RILEM TC 281-CCC: RILEM CPC-18R1—guideline for measuring the carbonation depth of hardened concrete using a pH indicator solution N2 - This recommendation provides a procedure for determining the carbonation depth on the surface of concrete by applying a pH indicator. This includes definitions of carbonation, carbonation depth and carbonation front, as well as descriptions of the different pH indicator solutions that can be used. Recommendations for testing laboratory-prepared specimens and those obtained from concrete structures are also given. This involves guidelines for sample preparation and/or extraction, CO2 exposure duration, carbonation depth determination and reporting of results. A section on data interpretation is also provided, as carbonation results are used for determining durability of concrete, as well as a criterion for materials selection or for carbon uptake calculations. The new Recommendation CPC-18R1 is intended to supersede the former RILEM recommendation CPC-18, particularly when prescribed as the preferred method for evaluating and reporting carbonation depths. KW - Carbonation KW - Concrete KW - pH indicator KW - Phenolphthalein KW - Testing PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656191 DO - https://doi.org/10.1617/s11527-026-02966-0 SN - 1359-5997 SN - 1871-6873 VL - 59 IS - 3 SP - 1 EP - 11 PB - Springer Nature AN - OPUS4-65619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schepers, Winfried A1 - Brinkgreve, RBJ A1 - Appel, S. T1 - Recommendations on finite element modelling of non-seismic excitation in soil-structure interaction problems N2 - Nowadays geotechnical engineering firms have powerful software tools to extent their consult-ing business also into dynamic soil-structure interaction, which before has been restricted to a rather small community of specialized experts in this field, and they certainly do. This is par-ticularly true with respect to non-seismic sources, that is all kinds of human induced vibrations. Hence, there is a demand from clients as well as from contractors to have guidance on the re-quirements as well as the limits of numerical modelling of soil-structure interaction. From the literature as well as from relevant standards, recommendations for the numerical modelling of soil-structure interaction problems involving seismic actions are well known, e. g. ASCE/SEI 4-16. There are, however, some particularities when dealing with human-induced vibrations, which are absent in seismic analyses. For human-induced excitations very little specific guid-ance has been published in the past. A machine foundation on a homogeneous half space ex-cited by harmonic loads with excitation frequency between 4 Hz and 64 Hz has been ana-lysed by means of several commercially available software packages. Parametric studies have been performed to verify if recommendations for seismic soil-structure analyses are valid for non-seismic analyses as well. This paper provides details on the benchmark example and the most important conclusions from the undertaken parametric studies. T2 - XII International Conference on Structural Dynamics CY - Delft, Netherlands DA - 02.07.2023 KW - Numerische Analysen KW - Referenzbeispiel KW - Maschinenfundament KW - Wellenausbreitung PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604931 DO - https://doi.org/10.1088/1742-6596/2647/8/082014 SN - 1742-6596 VL - 2647 IS - 25 SP - 1 EP - 13 PB - IOP Publishing AN - OPUS4-60493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Reduction in Train-Induced Vibrations—Calculations of Different Railway Lines and Mitigation Measures in the Transmission Path N2 - The reduction in train-induced ground vibrations by different railway lines and by mitigation measures in the propagation path was analysed in a unified approach by two-dimensional finite element calculations. In general, there was no reduction at low frequencies, and the reduction be-came stronger with increasing frequencies. A maximum reduction of 0.1 at high frequencies was established with an open trench. Reductions between 0.7 and 0.2 have been found for the other sit-uations, filled trenches, walls, plates, and blocks, as well as for railway lines on dams, in cuts and in a tunnel. Bridges can produce amplifications due to their resonance frequencies, but also strong reductions due to massive bridge piers. The influence of some parameters has been analysed, such as the bridge span, the inclination of the dam and the cut, the stiffness of the soil, and the tunnel structure. The dynamic track stiffnesses of a surface, bridge, and tunnel track have been calculated using the 3D finite-element boundary-element method for comparison with corresponding meas-urements. KW - Train-induced vibration KW - Mitigation KW - Trench KW - Obstacles KW - Tunnel KW - Bridge KW - Finite element KW - Boundary element PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579573 DO - https://doi.org/10.3390/app13116706 VL - 13 IS - 11 SP - 1 EP - 19 PB - MDPI CY - Basel AN - OPUS4-57957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosenbusch, Sjard Mathis A1 - Balzani, D. A1 - Unger, Jörg F. T1 - Regularization of softening plasticity models for explicit dynamics using a gradient-enhanced modified Johnson–Holmquist model N2 - The behavior of concrete under high strain rates is often described by plasticity models with softening, which is modeled by a reduction of the yield surface as a function of the local equivalent plastic strain. Many of these models are local and therefore produce mesh-dependent results. In this contribution, the gradient-enhancement of such models is investigated to mitigate the mesh-dependency. First, the mesh-dependency of these local formulations based on the analysis with a modified JH2 model as a representative for these constitutive formulations is demonstrated using a one-dimensional benchmark example. In the benchmark, the width of the damaged zone decreases upon mesh-refinement and the dissipated plastic energy tends to zero. It is further shown that a significantly small safety factor for the critical time step is needed in order to achieve accurate results for the benchmark example. The first investigated gradient-enhancement approach replaces the equivalent local plastic strain with its nonlocal counterpart. The enhancement is based on the inclusion of inertia and damping to the additional Helmholtz equation which enables the use of the central difference method as an explicit solver. This method successfully distributes the damage over several elements, however, the local equivalent plastic strain still localizes into one cell. The inclusion of hardening with respect to the local equivalent plastic strain inhibits the localization and the dissipated plastic energy converges with mesh-refinement. This is further confirmed in a two-dimensional wedge-splitting experiment and a four-point bending test where the damage pattern produced by the local model is mesh-dependent as well and the dissipated plastic energy tends to zero with mesh-refinement. The proposed nonlocal model with hardening results in a consistent damage pattern and the dissipated plastic energy converges. Furthermore, the nonlocal model with hardening is less sensitive to time step refinement, such that computational efficiency can be improved compared to the local model. The numerical experiments are implemented using the free open source tool FEniCSx and have been made available on Zenodo. KW - Gradient plasticity KW - Explicit dynamics KW - JH2 model KW - Concrete modeling KW - FEniCS KW - Mesh convergence KW - Time step convergence PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630453 DO - https://doi.org/10.1016/j.ijimpeng.2024.105209 SN - 1879-3509 VL - 198 SP - 1 EP - 18 PB - Elsevier Ltd. CY - Schweiz AN - OPUS4-63045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Niebergall, Ute A1 - Marschall, Niklas A1 - Meinel, Dietmar A1 - Böhning, Martin T1 - Relation of craze to crack length during slow crack growth phenomena in high‐density polyethylene N2 - The craze‐crack mechanism occurring in high‐density polyethylene (HDPE) causing slow crack growth and environmental stress cracking is investigated in detail with respect to the relation of crack length and the related craze zone. This is essential for the understanding of the resulting features of the formed fracture surface and their interpretation in the context of the transition from crack propagation to ductile shear deformation. It turns out that an already formed craze zone does not inevitably result in formation of a propagating crack, but could also undergo ductile failure. For the examination, the full notch creep test (FNCT) was employed with a subsequent advanced fracture surface analysis that was performed using various imaging techniques: light microscopy, laser scanning microscopy, scanning electron microscopy, and X‐ray micro computed tomography scan. FNCT specimens were progressively damaged for increasing durations under standard test conditions applying Arkopal, the standard surfactant solution, and biodiesel as test media were used to analyze the stepwise growth of cracks and crazes. From considerations based on well‐established fracture mechanics approaches, a theoretical correlation between the length of the actual crack and the length of the preceding craze zone was established that could be evidenced and affirmed by FNCT fracture surface analysis. Moreover, the yield strength of a HDPE material exposed to a certain medium as detected by a classic tensile test was found to be the crucial value of true stress to induce the transition from crack propagation due to the craze‐crack mechanism to shear deformation during FNCT measurements. Highlights - Progress of crack formation in high‐density polyethylene is analyzed by different imaging techniques - Determined growth rates depend on distinction between craze zone and crack - The ratio of the present crack to the anteceding craze zone is validated theoretically - The transition from crack propagation to ductile shear deformation is identified - An already formed craze zone may still fail by ductile mechanisms KW - Craze-crack mechanism KW - Environmental stress cracking (ESC) KW - Full notch creep test (FNCT) KW - Laser scanning microscopy (LSM) KW - Slow crack growth (SCG) KW - X-ray computed tomography (CT) PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601831 DO - https://doi.org/10.1002/pen.26698 SN - 1548-2634 VL - 64 IS - 6 SP - 2387 EP - 2403 PB - Wiley AN - OPUS4-60183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernal, S. A. A1 - Dhandapani, Y. A1 - Elakneswaran, Y. A1 - Gluth, Gregor A1 - Gruyaert, E. A1 - Juenger, M. C. G. A1 - Lothenbach, B. A1 - Olonade, K. A. A1 - Sakoparnig, M. A1 - Shi, Z. A1 - Thiel, C. A1 - Van den Heede, P. A1 - Vanoutrive, H. A1 - von Greve-Dierfeld, S. A1 - De Belie, N. A1 - Provis, J. L. T1 - Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete N2 - The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC ‘Carbonation of Concrete with Supplementary Cementitious Materials’ has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential). KW - Concrete KW - Cement KW - Carbonation KW - Testing KW - Standards PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609364 DO - https://doi.org/10.1617/s11527-024-02424-9 VL - 57 SP - 1 EP - 31 PB - Springer Nature AN - OPUS4-60936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vollpracht, A. A1 - Gluth, Gregor A1 - Rogiers, B. A1 - Uwanuakwa, I. D. A1 - Phung, Q. T. A1 - Villagran Zaccardi, Y. A1 - Thiel, C. A1 - Vanoutrive, H. A1 - Etcheverry, J. M. A1 - Gruyaert, E. A1 - Kamali-Bernard, S. A1 - Kanellopoulos, A. A1 - Zhao, Z. A1 - Martins, I. M. A1 - Rathnarajan, S. A1 - De Belie, N. T1 - Report of RILEM TC 281-CCC: insights into factors affecting the carbonation rate of concrete with SCMs revealed from data mining and machine learning approaches N2 - The RILEM TC 281–CCC ‘‘Carbonation of concrete with supplementary cementitious materials’’ conducted a study on the effects of supplementary cementitious materials (SCMs) on the carbonation rate of blended cement concretes and mortars. In this context, a comprehensive database has been established, consisting of 1044 concrete and mortar mixes with their associated carbonation depth data over time. The dataset comprises mix designs with a large variety of binders with up to 94% SCMs, collected from the literature as well as unpublished testing reports. The data includes chemical composition and physical properties of the raw materials, mix-designs, compressive strengths, curing and carbonation testing conditions. Natural carbonation was recorded for several years in many cases with both indoor and outdoor results. The database has been analysed to investigate the effects of binder composition and mix design, curing and preconditioning, and relative humidity on the carbonation rate. Furthermore, the accuracy of accelerated carbonation testing as well as possible correlations between compressive strength and carbonation resistance were evaluated. One approach to summerise the physical and chemical resistance in one parameter is the ratio of water content to content of carbonatable CaO (w/CaOreactive ratio). The analysis revealed that the w/CaOreactive ratio is a decisive factor for carbonation resistance, while curing and exposure conditions also influence carbonation. Under natural exposure conditions, the carbonation data exhibit significant variations. Nevertheless, probabilistic inference suggests that both accelerated and natural carbonation processes follow a square-root-of-time behavior, though accelerated and natural carbonation cannot be converted into each other without corrections. Additionally, a machine learning technique was employed to assess the influence of parameters governing the carbonation progress in concretes. KW - Carbonation KW - Supplementary cementitious materials KW - Concrete PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614388 DO - https://doi.org/10.1617/s11527-024-02465-0 SN - 1871-6873 SN - 1359-5997 VL - 57 IS - 9 SP - 1 EP - 33 PB - Springer Nature AN - OPUS4-61438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hu, W.-H A1 - Tang, D.-H. A1 - Wang, M. A1 - Liu, J.-L. A1 - Li, Z.-H. A1 - Lu, W. A1 - Teng, J. A1 - Said, Samir A1 - Rohrmann, R. G. T1 - Resonance Monitoring of a Horizontal Wind Turbine by Strain-Based Automated Operational Modal Analysis N2 - A strain-based automated operational modal analysis algorithm is proposed to track the long-term dynamic behavior of a horizontal wind turbine under operational conditions. This algorithm is firstly validated by a scaled wind turbine model, and then it is applied to the dynamic strain responses recorded from a 5 MW wind turbine system. We observed variations in the fundamental frequency and 1f, 3f excitation frequencies due to the mass imbalance of the blades and aerodynamic excitation by the tower dam or tower wake. Inspection of the Campbell diagram revealed that the adverse resonance phenomenon and Sommerfeld effect causing excessive vibrations of the wind tower. KW - Strain KW - Automated operational modal analysis KW - Resonance KW - Horizontal wind turbine PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-503350 DO - https://doi.org/10.3390/en13030579 VL - 13 IS - 3 SP - 579 EP - 584 PB - MDPI CY - Schweiz, Basel AN - OPUS4-50335 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heyn, A. A1 - Kotula, Stefan A1 - Ebell, Gino A1 - Babutzka, M. T1 - Results of a Round Robin Test for the Determination of Polarization Resistances on Differently Weathered Zinc Samples Using Gel Electrolytes N2 - This article presents the results of a round robin test throughout Germany with 19 participating institutions. Corrosion productlayer resistances (RL ) were determined on two differently weathered pure zinc samples and a sample activated with NaOH bymeans of electrochemical measurement of the linear polarization resistance (LPR) using agar‐based gel electrolytes. The roundrobin test was organized by the Bundesanstalt für Materialforschung und ‐prüfung (BAM) in Berlin. The measurements werecarried out by the participants in the period from May to July 2021. The results are summarized in this article comprising anassessment of the reproducibility and repeatability of the measurements. The methodology is suitable for distinguishing zincsurfaces after exposure to different atmospheres based on the corrosion product layer resistances (RL). In addition, possibleproblems in the application of the method were identified, and solutions for improving reproducibility and repeatability arediscussed. The results and knowledge from the round robin test are incorporated into a new test standard (DIN 50023:2024‐07)for this measurement method KW - Corrosion PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630546 DO - https://doi.org/10.1002/maco.202414696 SN - 1521-4176 SP - 1 EP - 12 PB - Wiley AN - OPUS4-63054 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Arbi, K. A1 - Bernal, S. A. A1 - Bondar, D. A1 - Castel, A. A1 - Chithiraputhiran, S. A1 - Dehghan, A. A1 - Dombrowski-Daube, K. A1 - Dubey, A. A1 - Ducman, V. A1 - Peterson, K. A1 - Pipilikaki, P. A1 - Valcke, S. L. A. A1 - Ye, G. A1 - Zuo, Y. A1 - Provis, J. L. T1 - RILEM TC 247-DTA round robin test: carbonation and chloride penetration testing of alkali-activated concretes N2 - Many standardised durability testing methods have been developed for Portland cement-based concretes, but require validation to determine whether they are also applicable to alkali-activated materials. To address this question, RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ carried out round robin testing of carbonation and chloride penetration test methods, applied to five different alkali-activated concretes based on fly ash, blast furnace slag or metakaolin. The methods appeared overall to demonstrate an intrinsic precision comparable to their precision when applied to conventional concretes. The ranking of test outcomes for pairs of concretes of similar binder chemistry was satisfactory, but rankings were not always reliable when comparing alkali-activated concretes based on different precursors. Accelerated carbonation testing gave similar results for fly ash-based and blast furnace slag-based alkali-activated concretes, whereas natural carbonation testing did not. Carbonation of concrete specimens was observed to have occurred already during curing, which has implications for extrapolation of carbonation testing results to longer service life periods. Accelerated chloride penetration testing according to NT BUILD 443 ranked the tested concretes consistently, while this was not the case for the rapid chloride migration test. Both of these chloride penetration testing methods exhibited comparatively low precision when applied to blast furnace slag-based concretes which are more resistant to chloride ingress than the other materials tested. KW - Alkali-activated materials KW - Durability KW - Carbonation KW - Chloride penetration KW - Concrete PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504045 DO - https://doi.org/10.1617/s11527-020-1449-3 SN - 1359-5997 SN - 1871-6873 VL - 53 IS - 1 SP - 21 PB - Springer Nature AN - OPUS4-50404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winnefeld, F. A1 - Gluth, Gregor A1 - Bernal, S. A. A1 - Bignozzi, M. C. A1 - Carabba, L. A1 - Chithiraputhiran, S. A1 - Dehghan, A. A1 - Dolenec, S. A1 - Dombrowski-Daube, K. A1 - Dubey, A. A1 - Ducman, V. A1 - Yu, J. A1 - Peterson, K. A1 - Stephan, D. A1 - Provis, J. L. T1 - RILEM TC 247-DTA round robin test: sulfate resistance, alkali-silica reaction and freeze–thaw resistance of alkali-activated concretes N2 - The RILEM technical committee TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ conducted a round robin testing programme to determine the validity of various durability testing methods, originally developed for Portland cement based-concretes, for the assessment of the durability of alkali-activated concretes. The outcomes of the round robin tests evaluating sulfate resistance, alkali-silica reaction (ASR) and freeze–thaw resistance are presented in this contribution. Five different alkali-activated concretes, based on ground granulated blast furnace slag, fly ash, or metakaolin were investigated. The extent of sulfate damage to concretes based on slag or fly ash seems to be limited when exposed to an Na2SO4 solution. The mixture based on metakaolin showed an excessive, very early expansion, followed by a dimensionally stable period, which cannot be explained at present. In the slag-based concretes, MgSO4 caused more expansion and visual damage than Na2SO4; however, the expansion limits defined in the respective standards were not exceeded. Both the ASTM C1293 and RILEM AAR-3.1 test methods for the determination of ASR expansion appear to give essentially reliable identification of expansion caused by highly reactive aggregates. Alkali-activated materials in combination with an unreactive or potentially expansive aggregate were in no case seen to cause larger expansions; only the aggregates of known very high reactivity were seen to be problematic. The results of freeze–thaw testing (with/without deicing salts) of alkali-activated concretes suggest an important influence of the curing conditions and experimental conditions on the test outcomes, which need to be understood before the tests can be reliably applied and interpreted. KW - Alkali-activated materials KW - Sulfate attack KW - Alkali silica reaction KW - Alkali aggregate reaction KW - Freeze-thaw attack PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515527 DO - https://doi.org/10.1617/s11527-020-01562-0 VL - 53 IS - 6 SP - 140 PB - Springer Nature AN - OPUS4-51552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Bernal, S. A. T1 - RILEM TC CUC: Carbon dioxide uptake by concrete during and after service life – Opening Letter N2 - The ability of cement to chemically bind CO2 in a carbonation reaction enables the material to act as a carbon sink, which could partly account for offsetting the CO2 emissions associated with cement production. In response to the many open questions in this context, the RILEM Technical Committee CUC was created in May 2024. The focus of the TC will be to facilitate discussions regarding the current approaches to estimate the CO2 uptake by cementitious materials (concrete and other construction products) during and after service life. This Opening Letter presents aspects of the motivation to establish the TC, a brief overview of the state of the art in the field, the scheduled work programme, and the anticipated impact of the TC outputs. Though it is not intended to be an exhaustive discussion of the challenges to be addressed, from what is summarized in this letter, it is clear that work is required to base estimates of CO2 uptake by cementitious materials on a data set that is as extensive, accurate and forward-looking as possible. It is anticipated that the inclusion of interdisciplinary perspectives and data from academia and industry will enable progress in the field. KW - Cement KW - Concrete KW - Recarbonation KW - Carbon dioxide uptake KW - Carbonation rate PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623724 DO - https://doi.org/10.21809/rilemtechlett.2024.208 SN - 2518-0231 VL - 9 SP - 61 EP - 67 PB - RILEM AN - OPUS4-62372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tabaka, Weronika A1 - Meinel, Dietmar A1 - Schartel, Bernhard T1 - Sacrifice Few to Save Many: Fire Protective Interlayers in Carbon- Fiber-Reinforced Laminates N2 - The fire protection of carbon-fiber-reinforced polymer (CFRP) laminates often relies on flame-retardant coatings, but in some applications, their efficacy may diminish upon direct fire exposure due to rapid pyrolysis. This study introduces an innovative approach by integrating protective interlayers within the laminate structure to enhance the fire resistance. Various materials, including ceramic composite WHIPOX, titanium foil, poly(etherimide) (PEI) foil, basalt fibers, rubber mat, and hemp fibers, were selected as protective interlayers. These interlayers were strategically placed within the laminate layout to form a sacrificial barrier, safeguarding the integrity of the composite. Bench-scale fire resistance tests were conducted, where fire (180 kW/m2) was applied directly to the one side of the specimen by a burner while a compressive load was applied at the same time. Results indicate significant prolongation of time to failure for CFRP laminates with protective interlayers, which is up to 10 times longer. This innovative approach represents a potential advance in fire protection strategies for CFRP laminates, offering improved resilience against fire-induced structural failure. KW - Composites in fire KW - Fire resistance KW - Fire retardant interlayers KW - Laminate design KW - Carbon fibre reinforced PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601943 DO - https://doi.org/10.1021/acsomega.4c01408 SN - 2470-1343 VL - 9 IS - 22 SP - 23703 EP - 23712 PB - ACS AN - OPUS4-60194 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Piechnik, Kira A1 - Hofmann-Böllinghaus, Anja A1 - Klippel, Andrea T1 - Self‐ignition of forest soil samples demonstrated through hot storage tests N2 - AbstractThe increasing threat of forest fires on a global scale is not only a matter of concern due to the potential harm they may cause to both human and animal life but also due to their significant role in exacerbating climate change. In light of these circumstances, one might inquire as to whether forest soil can self‐ignite and, if so, under what conditions and at what temperatures this phenomenon may occur. This question is being addressed in the German pilot “Fire science of wildfires and safety measures” of the EU project TREEADS, and the first results are presented below. The importance of basic research into the self‐ignition of forest soil cannot be underestimated, as it provides crucial knowledge to prevent forest fires and protect human and animal health. Furthermore, mitigating the occurrence of forest fires can also play a role in reducing greenhouse gas emissions, contributing to global efforts to combat climate change. The procedure of the hot storage test is an effective means of determining whether a material can self‐ignite. During the investigation of six soil samples, it was found that five of them were indeed capable of self‐ignition. In addition to determining whether the material ignites, the modified hot storage test also analyzed the resulting smoke gases and measured their concentration. The research question of whether regional forest soil is capable of self‐ignition can be answered with yes based on these initial tests. Further experiments are needed to determine if self‐ignition causes forest fires. KW - FTIR KW - Hot storage KW - Ignition KW - Soil KW - Wildfire PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594617 DO - https://doi.org/10.1002/fam.3198 SN - 1099-1018 VL - 48 IS - 4 SP - 495 EP - 507 PB - Wiley CY - New York, NY AN - OPUS4-59461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seher, Julia A1 - Fröba, M. T1 - Shape matters: The effect of particle morphology on the fast-charging performance of LiFePO4/C nanoparticle composite electrodes N2 - For the successful use of lithium-ion batteries in automotive applications, reliable availability of high storage capacity and very short recharging times are essential. In order to develop the perfect battery for a certain application, structure–property relationships of each active material must be fully understood. LiFePO4 is of great interest due to its fast-charging capability and high stability regarding its thermal resistance and chemical reactivity. The anisotropic lithium-ion diffusion through the LiFePO4 crystal structure indicates a strong dependence of the electrochemical performance of a nanostructured active material on particle morphology. In this paper, the relationship of the particle morphology and fast-charging capability of LiFePO4/C core/shell nanoparticles in half-cells was studied. For this purpose, a new multistep synthesis strategy was developed. It involves the combination of a solvothermal synthesis followed by an in situ polymer coating and thermal calcination step. Monodisperse rodlike LiFePO4 nanoparticles with comparable elongation along the b-axis (30–50 nm) and a varying aspect ratio c/a (2.4–6.9) were obtained. A strong correlation of the fast-charging capability with the aspect ratio c/a was observed. When using LiFePO4 nanoparticles with the smallest aspect ratio c/a, the best electrochemical performance was received regarding the specific capacity at high C-rates and the cycling stability. A reduction of the aspect ratio c/a by 30% (3.6 to 2.4) was found to enhance the charge capacity at 10 C up to an order of magnitude (7.4–73 mA h·g–1). KW - LiFePO4 KW - Schnellladung KW - Nanoparticles KW - Carbon KW - Chemical synthesis KW - Electrochemical cells KW - Materials PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-533004 DO - https://doi.org/10.1021/acsomega.1c03432 SN - 2470-1343 VL - 6 IS - 37 SP - 24062 EP - 24069 PB - American Chemical Society CY - Washington, DC AN - OPUS4-53300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vlach, Tomáš A1 - Řepka, Jakub A1 - Hájek, Jakub A1 - Pošta, Jan A1 - Fürst, Richard A1 - Hájek, Petr T1 - Shear Capacity of Hollow High-Performance Concrete Beams with Cross-Wound Carbon Fiber-Reinforced Polymer Reinforcement N2 - This paper introduces cross-wound CFRP shear reinforcement of hollow HPC beams. The CFRP reinforcement was manufactured in the form of a square tubular mesh from carbon rovings oriented at ±45° from the longitudinal axis. The shear reinforcement was made in two variants from carbon yarns with linear densities of 1600 and 3700 tex. Tensile reinforcement made of BFRP bars was positioned directly around the hollow core and was used as a platform for manual winding of the shear reinforcement. The hollow beams were subjected to a three-point bending test with four configurations of the tensile BFRP reinforcement for better evaluation of the effect of the shear reinforcement under different conditions. The 1600 tex shear reinforcement increased the ultimate flexural strength by at least 89% compared to specimens without any shear reinforcement. The 3700 tex shear reinforcement yielded slightly better results in most cases but was not utilized to its full shear capacity as these specimens always failed in shear due to the delamination of the concrete matrix from the shear reinforcement. There was too much reinforcement in the beam cross-section. KW - Hollow concrete beam KW - Shear reinforcement KW - Composite reinforcement KW - Woven reinforcement KW - Cross-wound reinforcement KW - Fiber-reinforced polymer KW - High-performance concrete PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623868 DO - https://doi.org/10.3390/polym17010075 SN - 2073-4360 VL - 17 IS - 1 SP - 1 EP - 13 PB - MDPI AN - OPUS4-62386 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Giv, Ali Nemati A1 - Asante, Bright A1 - Yan, Libo A1 - Kasal, Bohumil T1 - Shear performance and durability of adhesively bonded spruce wood-concrete composite joints: Effects of indoor and outdoor environmental conditions, mechanical load, and their coupled effect N2 - A long-term study was conducted on double-lap spruce wood-concrete joints to investigate their shear strength and stiffness over a 12-month period. These joints were manufactured using both wet and dry processes, each incorporating two adhesive types for bonding the wood to the concrete: a brittle epoxy and a ductile polyurethane (PUR). The experimental design exposed the joints to three specific long-term environments: (1) outdoor exposure, (2) indoor conditions with applied load, and (3) outdoor conditions with applied load. The wood concrete joints exposed to outdoor conditions were subjected to destructive shear testing at intervals of 0 (serving as the reference sample), 2, 4, 6, and 12 months, respectively. For joints subjected to both indoor and outdoor conditions with shear loading, the shear deformation of joints was monitored continuously over the 12 months before performing the destructive tests. A gradual reduction in the shear stiffness and strength of dry joints (produced using the dry bond method) exposed to outdoor conditions was observed over a 12-month period, primarily due to bond failure at the concrete-adhesive interface. The wet joints exhibited no degradation in shear stiffness and strength across long-term conditions over the same period. The bond failure observed in dry joints was predominantly associated with stresses arising from dimensional changes in the wood. No degradation was found in the cross-linking density of the adhesive or in the concrete’s compressive stiffness and strength. KW - Adhesively bonded joints KW - Long-term study KW - Ductile PUR KW - Brittle epoxy KW - Outdoor condition KW - Mechanical load KW - Indoor condition PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608878 DO - https://doi.org/10.1016/j.conbuildmat.2024.136905 VL - 436 SP - 1 EP - 22 PB - Elsevier BV AN - OPUS4-60887 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Simple and fast prediction of train-induced track forces, ground and building vibrations N2 - A simple and fast prediction scheme is presented for train induced ground and building vibrations. Simple models such as (1-dimensional) transfer matrices are used for the vehicle-track-soil interaction and for the building-soil interaction. The wave propagation through layered soils is approximated by a frequency-dependent homogeneous half-space. The prediction is divided into the parts “emission” (excitation by railway traffic), “transmission” (wave propagation through the soil) and “immission” (transfer into a building). The link between the modules is made by the excitation force between emission and transmission, and by the free-field vibration between transmission and immission. All formula for the simple vehicle-track, soil and building models are given in this article. The behaviour of the models is demonstrated by typical examples, that is the mitigation of train vibrations by elastic track elements, the low- and high-frequency cut-offs characteristic for layered soils, and the interacting soil, wall and floor resonances of multi-storey buildings. It is shown that the results of the simple prediction models can well represent the behaviour of the more time-consuming detailed models, the finite-element boundary-element models of the track, the wavenumber integrals for the soil, and the three-dimensional finite-element models of the building. In addition, measurement examples are given for each part of the prediction confirming that the methods provide reasonable results. As the prediction models are fast in calculation, many predictions can be done, for example to assess the environmental effect along a new railway line. The simple models have the additional advantage that the user needs to know only a minimum of parameters. So, the prediction is fast and user-friendly, but also theoretically and experimentally well-founded. KW - Railway induced vibration KW - Ground vibration KW - Layered soil KW - Building response KW - Excitation forces KW - Track and vehicle irregularities PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513340 DO - https://doi.org/10.1007/s40534-020-00218-7 SN - 2662-4745 VL - 28 IS - 3 SP - 232 EP - 250 PB - Springer AN - OPUS4-51334 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nandish, Ranjith A1 - Knaust, Christian A1 - Hofmann-Böllinghaus, Anja A1 - Gnutzmann, Tanja A1 - Zehfuß, Jochen T1 - Simulation of wood pyrolysis with component-based mechanism N2 - This paper presents a comprehensive fire simulation study that models the pyrolysis process of beech wood using kinetic parameters with the Fire Dynamics Simulator (FDS). The kinetic methodology is based on the application of these kinetic parameters to govern the underlying pyrolysis reactions. The primary objective was to numerically model the pyrolysis process for beech wood using both single-component (single-step, single reaction scheme) and multi-component (single-step, multi-reaction scheme) kinetic reaction schemes. The accuracy of the numerical model was validated by comparing FDS simulation results with experimental data obtained from thermogravimetric analysis (TGA) and cone calorimeter tests. This approach aids in identifying reliable kinetic reaction input parameters for modelling wood fires. A case study was included to demonstrate the implementation of the kinetic reaction schemes. Numerical results from the TGA simulations for the small-scale pure cellulose test using the single-component approach exhibit consistency with the experimental data. Furthermore, the results demonstrated that the multi-component approach more accurately replicates the shape of the experimental curve for beech wood compared to the single-component approach. However, discrepancies in the tail regions of the curves obtained from the FDS simulations showed the need for further improvement in the modelling approach, particularly regarding the exclusion of char oxidation reactions, which needs to be investigated further. KW - Simulation KW - Wood PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639272 DO - https://doi.org/10.1007/s00231-025-03571-7 SN - 0947-7411 VL - 61 IS - 6 SP - 1 EP - 14 PB - Springer Science and Business Media LLC AN - OPUS4-63927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Site-specific amplitude-distance laws, wave velocities, damping, and transfer functions of the soil from hammer impacts and application to railway-induced ground vibration – Similarities and mid-frequency differences N2 - The propagation of ground vibrations is theoretically analysed with frequency-wavenumber and simplified methods. Experimental methods are presented which can characterise the site-specific ground vibrations by wave velocities, stiffness and damping. Measurements with hammer and train excitation have been performed at several sites. The one-third octave spectra show the stiffness-dependent amplitudes and the low- and high-frequency filter effects due to the layering and the damping of the soil. Specific train effects, an additional high-frequency filter, the sleeper passage frequency, and an amplified mid-frequency component can be clearly found. The attenuation with distance is analysed in detail where the theoretical exponential and the empirical frequency-dependent power law are considered. Hammer and train excitation show the same site-specific effects which are mainly due to the stronger or weaker damping of the soil. The train attenuation is generally weaker than the hammer attenuation. The attenuation exponent of the power law, which is strongly dependent on the site and the frequency, is reduced for the train vibration by 0.3 to 0.5 in agreement with the theory. Reasons are discussed for the overall power law and for the dominating mid-frequency component. KW - Hammer impact KW - Train passage KW - Layered soil KW - Attenuation KW - Filter effects KW - Randomly heterogeneous soil KW - Scattering PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-585020 DO - https://doi.org/10.1007/s42417-023-01095-0 SN - 2366-2557 SP - 1 EP - 17 PB - Springer AN - OPUS4-58502 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Soil–structure interaction and damping by the soil - effects of foundation groups, foundation flexibility, soil stiffness and layers N2 - In many tasks of railway vibration, the structure, that is, the track, a bridge, and a nearby building and its floors, is coupled to the soil, and the soil–structure interaction and the damping by the soil should be included in the analysis to obtain realistic resonance frequencies and amplitudes. The stiffness and damping of a variety of foundations is calculated by an indirect boundary element method which uses fundamental solutions, is meshless, uses collocation points on the boundary, and solves the singularity by an appropriate averaging over a part of the surface. The boundary element method is coupled with the finite element method in the case of flexible foundations such as beams, plates, piles, and railway tracks. The results, the frequency-dependent stiffness and damping of single and groups of rigid foundations on homogeneous and layered soil and the amplitude and phase of the dynamic compliance of flexible foundations, show that the simple constant stiffness and damping values of a rigid footing on homogeneous soil are often misleading and do not represent well the reality. The damping may be higher in some special cases, but, in most cases, the damping is lower than expected fromthe simple theory. Some applications and measurements demonstrate the importance of the correct damping by the soil. KW - Soil–structure interaction KW - Soil dynamics KW - Radiation damping of the soil KW - Rigid foundation KW - Flexible foundation KW - Foundation groups KW - Boundary element method KW - Vibration measurement PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-627007 DO - https://doi.org/10.3390/vibration8010005 SN - 2571-631X VL - 8 IS - 5 SP - 1 EP - 28 PB - MDPI CY - Basel, Schweiz AN - OPUS4-62700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Sebastian A1 - Bertmer, M. A1 - Gluth, Gregor T1 - Sol–gel synthesis and characterization of lithium aluminate (L–A–H) and lithium aluminosilicate (L–A–S–H) gels N2 - Hydrous lithium aluminosilicate (L–A–S–H) and lithium aluminate (L–A–H) gels are candidate precursors for glass-ceramics and ceramics with potential advantages over conventional processing routes. However, their structure before calcination remained largely unknown, despite the importance of precursor structure on the properties of the resulting materials. In the present study, it is demonstrated that L–A–S–H and L–A–H gels with Li/Al ≤ 1 can be produced via an organic steric entrapment route, while higher Li/Al ratios lead to crystallization of gibbsite or nordstrandite. The composition and the structure of the gels was studied by thermogravimetric analysis, X-ray diffraction, 27Al and 29Si magic-angle spinning nuclear magnetic resonance, and Raman spectroscopy. Aluminium was found to be almost exclusively in six-fold coordination in both the L–A–H and the L–A–S–H gels. Silicon in the L–A–S–H gels was mainly in Q4 sites and to a lesser extent in Q3 sites (four-fold coordination with no Si–O–Al bonds). The results thus indicate that silica-rich and aluminium-rich domains formed in these gels. KW - Lithium aluminosilicates KW - Raman spectroscopy KW - Sol-gel PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-558756 DO - https://doi.org/10.1111/ijac.14187 SN - 1546-542X VL - 19 IS - 6 SP - 3179 EP - 3190 PB - Wiley AN - OPUS4-55875 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Some resonance effects of non-typical trains and railway bridges investigated by a frequency-domain method N2 - The resonances of railway bridges have often been analysed for short bridges under periodical high-speed trains, for simply supported one-span bridges, for the fundamental bridge mode, and by time-domain analyses. Many time-consuming calculations have been performed to establish simplified rules for standards. In this contribution, the passage of different (existing, new and hypothetic) trains over different (simply supported, integral, multi-span, continuous) bridges will be analysed in frequency domain by using three separated spectra with the purpose to get a better physical insight in the phenomena. At first, the excitation spectrum of the modal forces is built by the mode shape and the passage time of the train over the bridge. The second spectrum is the frequency response function of the bridge which include the modal frequency, damping and mass. The third part is the spectrum of the axle sequence of an arbitrary train which is not limited to periodical or specific (conventional, articulated, regular or standard) trains and which does not include any bridge parameters. The final solution in frequency domain is obtained as the product of these three complex, strongly varying spectra for the dominating bridge mode or in general as the sum of these products over all relevant bridge modes. The time domain solution is obtained via the inverse Fourier transform, and the resulting time histories have been successfully compared with some measurement results. The method is applied to the vertical and torsional modes of a mid-long single-span bridge on elastomeric bearings under standard train speeds, to a short two-span bridge under high-speed traffic, and to a long three-span integral bridge under long periodical freight trains. Different resonance and cancellation effects have been found for systematically varied train speeds according to the axle sequence of the whole train which is dominated by the two locomotives in that case. To be more specific, the first torsional mode of the mid-span bridge is excited for a train speed of 100 km/h whereas the second bending mode is excited for a train speed of 160 km/h. In both cases, the other mode is suppressed by the minima of the axle-distance spectra. In addition, the case of the German high-speed train ICE4, a Maglev train on a viaduct, and the very high-speed hyperloop case will be discussed briefly. In general, it is shown that resonance effects are also worth to be studied for freight and passenger trains with lower speeds. KW - Rail bridge KW - Resonance KW - ICE4 KW - MAGLEV KW - Hyperloop KW - Continuous bridge KW - Multi-span bridge PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612595 DO - https://doi.org/10.1088/1742-6596/2647/25/252014 VL - 2647 SP - 1 EP - 11 PB - IOP Publishing AN - OPUS4-61259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ferrier, Emmanuel A1 - Michel, Laurent A1 - Thiele, Marc A1 - Mercier, Julien T1 - Strain-rate effect on the bond strength of external bonded reinforced carbon fiber-reinforced polymer for concrete structure N2 - The aim of the presented study is to investigate the dynamic loading strength of an external bonded fiber-reinforced polymers (FRP) system under seismic loading. 16 bonded FRP samples under different loading speeds ranging as 0.0000167–0.8 m /s were examined to determine the characteristics of the FRP bond strength on the concrete. The mechanical tests involved measuring the concrete/FRP shear properties using a double-lap shear test. Sixteen concrete specimens were cast, strengthened and surface preparation, instrumented, and driven to failure in the LMC laboratory and the BAM laboratory (Germany). Dynamic loading increased the bonded strength mainly because of an increase in the concrete tensile strength. Experimental data are then analysed and competed with the equation given by the new European standard that develop the design of external bonded FRP. The characteristic properties and bonded strength obtained by design equation were compared. Based on the results design equation are modified. KW - EBR strengthening system KW - Desing bond strength KW - Durability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625354 DO - https://doi.org/10.1016/j.conbuildmat.2025.140216 SN - 1879-0526 VL - 466 SP - 1 EP - 14 PB - Elsevier Ltd. AN - OPUS4-62535 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seifert, Lando A1 - Grunewald, Andreas A1 - Müller, Thoralf A1 - Ebell, Gino T1 - Stress corrosion tests for prestressing steels—Part 1: The influence of surface condition and test solution composition on hydrogen charging N2 - Tests for assessing prestressing steels' susceptibility to hydrogen‐induced stress corrosion cracking are essential for approvals, in‐house monitoring, and third‐party material testing. According to ISO 15630‐3, the time to brittle fracture by constant load under corrosive conditions in thiocyanate test solutions (A or B) at 50°C is measured. In the literature, a high scattering in stress corrosion tests is reported, which questions the integrity of the test procedure. This paper shows the results of studies about the influence of solution composition on hydrogen charging in electrochemical and permeation measurements. Electrochemical experiments show that polished steel surfaces without common drawing layers have more consistent free corrosion currents, polarization resistances, and B‐values in solution A with low scattering compared to the solution B experiments. The influence of temperature at 50°C and an ambient temperature of 22°C was also tested. KW - Drawing layers KW - Hydrogen‐induced stress corrosion cracking KW - Permeation measurements KW - Prestressing steels KW - Stress corrosion tests KW - Surface conditions KW - Test solutions PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598738 DO - https://doi.org/10.1002/maco.202313948 VL - 75 SP - 1506 EP - 1518 PB - Wiley‐VCH GmbH AN - OPUS4-59873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seifert, Lando A1 - Müller, Thoralf A1 - Bettge, Dirk A1 - Moersch, Jörg A1 - Isecke, Bernd A1 - Ebell, Gino T1 - Stress Corrosion Tests for Prestressing Steels—Part 2: Susceptibility of Quenched and Tempered Wires—Influence of Chromium N2 - Due to the risk of failure in existing prestressed concrete bridges, the assessment of the susceptibility of prestressing steel to hydrogen‐induced stress corrosion cracking will become more important in the future. At present, the used normative ISO 15630‐3 test gives unpersuasive and diverging results using a free corrosion approach for the needed hydrogen charging for stress corrosion cracking initiation. A newly developed test method uses the cathodic polarization to control the supply of electrons for hydrogen charging instead of an uncontrolled and variable supply of electrons by metal dissolution during free corrosion. Experimental data shows a reliable differentiation between highly susceptible known quenched and tempered wires and robust cold‐drawn wires with this new test. A round robin with eight participating testing institutes demonstrated the reproducibility of results testing a cold‐drawn wire batch of St 1470/1670. In contrast to previously reported experience in the literature, the new method ranks the Cr‐alloyed quenched and tempered (“new‐type”) wires as highly‐susceptible as the “old‐type” wires without Cr‐alloy. KW - Cathodic polarization KW - Chemical composition KW - Chromium KW - Prestressing steels KW - Quenched and tempered KW - Stress corrosion cracking KW - Susceptibility KW - Wires PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639735 DO - https://doi.org/10.1002/maco.70033 SN - 0947-5117 SP - 1 EP - 10 PB - Wiley-VCH CY - Weinheim AN - OPUS4-63973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiehle, Philipp A1 - Baier, Johanna A1 - Thiele, Marc T1 - Structural Design of Earth Masonry in Accordance with Eurocode 6 – Considering Moisture Content and E/fk Ratio N2 - The load‐bearing behaviour of earth masonry is similar to conventional masonry, with two key differences: compressive strength and Young's modulus are dependent on moisture content, and the ratio between Young's modulus and characteristic compressive strength (E/fk) is significantly lower. The current design concept according to the Lehmbau Regeln does not explicitly address these factors, relying instead on a general safety margin, leading to an underestimation of the load‐bearing capacity of modern earth masonry.Compression tests on small‐scale masonry specimens and storey‐high walls revealed that compressive strength and Young's modulus decrease inversely proportional to the increase in relative humidity. Additionally, it was found that conventional masonry design guidelines overestimate the buckling resistance of earth masonry due to its low E/fk ratio of ∼440. However, this ratio remains independent of moisture content, simplifying structural design, as the load‐bearing capacity is only influenced by wall slenderness.The study's findings form the foundation for the newly published German design standard DIN 18940, which explicitly considers moisture content through service classes with moisture factors and addresses the low E/fk ratio with a bilinear adaptation of the reduction factor considering the slenderness. Along with the introduction of the semi‐probabilistic design concept and rigid‐plastic determination of cross‐sectional load‐bearing capacity, modern earth masonry can now be applied in buildings up to four storeys. T2 - Earth Builder Summit CY - Biberach, Germany DA - 06.03.2025 KW - Service class KW - Earth masonry KW - Structural design KW - Moisture PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637803 DO - https://doi.org/10.1002/cepa.3287 SN - 2509-7075 VL - 8 IS - 1 SP - 9 EP - 21 PB - Ernst & Sohn GmbH AN - OPUS4-63780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wallau, Wilma A1 - Recknagel, Christoph A1 - Smales, Glen Jacob T1 - Structural silicone sealants after exposure to laboratory test for durability assessment N2 - During the service life of structural sealant glazing (SSG) facades, the loadbearing capacity of the silicone bonds needs to be guaranteed. Laboratory Tests can assess the durability of SSG-systems based on mechanical characteristics of the bond after simultaneous exposure to both climatic and mechanical loads. This article studies how the material characteristics of two common structural sealants are affected by laboratory and field exposure. Dynamic mechanical Analysis (DMA) confirms a reduction in the dynamic modulus of exposed Silicone samples. Results from thermogravimetric analysis, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and small-angle X-ray scattering/wide-angle X-ray scattering show differences between the two sealants and indicate no/minor changes in the composition and morphology of the laboratory and field exposed sealants. Mechanical characterization methods, such as DMA, and tensile and shear testing of the structural bond, are shown to be sensitive toward the combined climatic and mechanical loadings, and are hence suitable for studying degradation mechanisms of structural sealants. KW - Aging KW - Analytical methods KW - Fatigue KW - Silicone elastomer KW - Structural sealant glazing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527217 DO - https://doi.org/10.1002/app.50881 VL - 138 IS - 35 SP - 50881 PB - Wiley AN - OPUS4-52721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Huang, J. A1 - Szymoniak, Paulina A1 - Bojdys, M. J. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Structure and molecular mobility of phosphinine-based covalent organic frameworks – glass transition of amorphous COFs N2 - Two-dimensional covalent organic frameworks (COFs) based on phosphinine and thiophene building blocks have been synthesized with two different side groups. The materials are denoted as CPSF-MeO and CPSF-EtO where CxxF correspond to the covalent framework, whereas P and S are related to heteroatoms phosphorous and sulfur. MeO and EtO indicate the substituents, i.e. methoxy and ethoxy. Their morphologies were studied by scanning electron microcopy and X-ray scattering. The absence of crystalline reflexes in the X-ray pattern reveal that both materials are amorphous and can be considered as glasses. Furthermore, N2 adsorption measurements indicate substantial Brunauer–Emmett–Teller (BET) surface area values pointing to the formation of three-dimensional pores by stacking of the aromatic 2D layer. An analysis of the porosity of both COFs showed a mean radius of the pores to be of ca. 4 nm, consistent with their chemical structure. The COFs form nanoparticles with a radius of around 100 nm. The thermal behavior of the COFs was further investigated by fast scanning calorimetry. These investigations showed that both COFs undergo a glass transition. The glass transition temperature of CPSF-EtO is found to be ca. 100 K higher than that for CPSF-MeO. This large difference in the glass transition is discussed to be due to a change in the interaction of the COF sheets induced by the longer ethoxy group. It might be assumed that for CPSF-EtO more individual COF sheets assemble to larger stacks than for CPSF-MeO. This agrees with the much larger surface area value found for CPSF-EtO compared to CPSF-MeO. To corroborate the results obtained be fast scanning calorimetry dielectric measurements were conducted which confirm the occurrence of a dynamic glass transition. The estimated temperature dependence of the relaxation rates of the dielectric relaxation and their absolute values agrees well with the data obtained by fast scanning calorimetry. Considering the fragility approach to the glass transition, it was further found that CPSF-MeO is a fragile glass former whereas CPSF-EtO behaves as a strong glass forming material. This difference in the fragility points also to distinct differences in the interaction between the 2D COF molecules in both materials. KW - Covalent Organic frameworks PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596770 DO - https://doi.org/10.1039/d3ma01123b SP - 1 EP - 10 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Aristia, Gabriela A1 - Le, Quynh Hoa A1 - Nofz, Marianne A1 - Sojref, Regine A1 - Bäßler, Ralph T1 - Study of Al2O3 Sol-Gel Coatings on X20Cr13 in Artificial North German Basin Geothermal Water at 150 °C N2 - Al2O3 has been widely used as a coating in industrial applications due to its excellent chemical and thermal resistance. Considering high temperatures and aggressive mediums exist in geothermal systems, Al2O3 can be a potential coating candidate to protect steels in geothermal applications. In this study, γ-Al2O3 was used as a coating on martensitic steels by applying AlOOH sol followed by a heat treatment at 600 °C. To evaluate the coating application process, one-, two-, and three-layer coatings were tested in the artificial North German Basin (NGB), containing 166 g/L Cl−, at 150 °C and 1 MPa for 168 h. To reveal the stability of the Al2O3 coating in NGB solution, three-layer coatings were used in exposure tests for 24, 168, 672, and 1296 h, followed by surface and cross-section characterization. SEM images show that the Al2O3 coating was stable up to 1296 h of exposure, where the outer layer mostly transformed into boehmite AlOOH with needle-like crystals dominating the surface. Closer analysis of cross-sections showed that the interface between each layer was affected in long-term exposure tests, which caused local delamination after 168 h of exposure. In separate experiments, electrochemical impedance spectroscopy (EIS) was performed at 150 °C to evaluate the changes of coatings within the first 24 h. Results showed that the most significant decrease in the impedance is within 6 h, which can be associated with the electrolyte penetration through the coating, followed by the formation of AlOOH. Here, results of both short-term EIS measurements (up to 24 h) and long-term exposure tests (up to 1296 h) are discussed. KW - Al2O3 KW - Geothermal KW - Martensitic steels KW - Behmite KW - Corrosion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525551 DO - https://doi.org/10.3390/coatings11050526 SN - 2079-6412 VL - 11 IS - 5 SP - 526 PB - MDPI CY - Basel AN - OPUS4-52555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dey, R. A1 - Dudziak, Mateusz A1 - Prescher, A. A1 - Kreitsmann, T. A1 - Zhang, K. A1 - Posten, C. A1 - Thomson, C. A1 - Schartel, Bernhard A1 - Ullrich, M. S. A1 - Thomson, L. T1 - Sustainable Flame-Retardant Poly Lactic AcidBiocomposites Reinforced with Polyphosphate-EnrichedMicroalgae: Unlocking the Potential of Hyper-Compensation N2 - This study examines the dual benefits of microalgae cultivation for wastewatertreatment and the enhancement of polylactic acid-based biocomposites. UsingDesmodesmus sp. in a photobioreactor, both batch and continuous operationsachieve total nitrogen (TN) and total phosphorus (TP) removal rates of up to99.9%, maintaining TN and TP levels below 0.02 mg L−1 in the effluent, aligningwith European discharge standards. Continuous cultivation increases biomassproductivity from 0.102 to 0.43 g L−1 day−1 , a 322% improvement over batchoperations. Nutrient starvation followed by reintroduction to nutrient-richwastewater induces hyper-compensation luxury uptake, with P-enrichedcells accumulating 1.33% intracellular P within six hours — 21% higherthan natural accumulation. The results reveal that luxury phosphorus uptakein microalgae follows a triphasic system of uptake and storage, challengingthe previously suggested biphasic model. When incorporated into Poly lacticacid (PLA), the biomass enhances versatility, offering potential replacementof inorganic P in industrial applications, particularly flame retardants.Pyrolysis and cone calorimetry confirm the thermal and fire-retardantbenefits, with a 20% reduction in peak heat release rate and increased charyield. This work highlights microalgae’s role in sustainable biocomposites,supporting wastewater treatment, nutrient recovery, and CO2 sequestration. KW - biocomposites KW - biopolymers KW - Flame-retardant KW - Hyper compensation KW - Phycoremediation KW - Wastewater treatment PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640408 DO - https://doi.org/10.1002/adsu.202500251 SN - 2366-7486 VL - 9 IS - 8 SP - 1 EP - 11 PB - Wiley VHC-Verlag AN - OPUS4-64040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - The dynamic train-track interaction on a bridge and in a tunnel compared with the simultaneous vehicle, track, and ground vibration measurements at a surface line N2 - The vehicle–track interaction generates forces and consequently vibrations in the environment. The interaction has been analysed by the simultaneous measurements of vehicle, track and ground vibrations during test runs with varied train speeds. The special effects of the passage over a bridge and through a tunnel are studied and compared with the measurements on a conventional ballasted surface line. The maximum amplitudes, narrow band and one-third octave band spectra are presented for the axle-box accelerations and for the track, bridge and ground vibrations. The different frequencies and frequency bands are related to wheel out-of-roundness, track alignment errors, the sleeper passage and the wheelset–track resonance. An axle impulse component has been observed at the track, at the near-field soil and as a scattered version in the far field. Specific results can be found for the bridge track, where clearly speed-dependent bridge resonances occur due to the axle sequence of the train, and for the tunnel track where soft rail pads are responsible for a strong amplification around the wheelset–track resonance. On the other hand, the axle impulses are strongly reduced by the tunnel track, and the scattered axle impulse component is not as relevant as for the surface track. As a consequence, a strong mid-frequency amplitude reduction of the tunnel compared to the surface line has been measured for low and high train speeds by the Federal Institute of Material Research and Testing (BAM) and by other institutes. KW - Vehicle–track interaction KW - Ground vibration KW - Tunnel-to-surface reduction KW - Bridge resonance KW - Axle sequence PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-585139 DO - https://doi.org/10.3390/app131910992 VL - 13 IS - 19 SP - 1 EP - 23 PB - MDPI CY - Basel, Schweiz AN - OPUS4-58513 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Turski Silva Diniz, Analice A1 - Schartel, Bernhard T1 - The effects of property variation on the dripping behaviour of polymers during UL94 test simulated by particle finite element method N2 - The dripping behaviour of polymers is often observed experimentally through the UL94 flammability standard test. In this work, polymeric dripping under fire is investigated numerically using particle finite element method. A parametric analysis was carried out to observe the influence of a single property on overall dripping behaviour via a UL94 vertical test model. Surrogates and property ranges were defined for variation of the following parameters: glass transition temperature (Tg), melting temperature (Tm), decomposition temperature (Td), density (ρ), specific heat capacity (Cp), apparent effective heat of combustion of the volatiles, char yield (μ), thermal conductivity (k), and viscosity (η). Polyamide, poly(ether ether ketone), poly(methyl methacrylate), and polysulfone were used as benchmarks. Simulated results showed that specific heat capacity, thermal conductivity, and char yield allied with viscosity were the properties that most influenced dripping behaviour (starting time and occurrence). KW - Dripping KW - PFEM KW - UL 94 KW - Simulation KW - Fire behaviour PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597449 DO - https://doi.org/10.1515/epoly-2023-0194 SN - 1618-7229 VL - 24 IS - 1 PB - De Gruyter AN - OPUS4-59744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittrich, Tim A1 - Weise, Frank A1 - Stelzner, Ludwig T1 - The impact of blended cements on the spalling behavior of concrete at elevated temperatures: a review N2 - The cement and concrete industries are striving to reduce the CO2 emissions caused by the production of Portland cement. An effective way to achieve this is to replace Portland cement clinker with more environmentally friendly supplementary cementitious materials (SCMs) to produce blended cements. A variety of different SCMs are used today, from fly ash to more exotic options such as rice husk ash or waste glass powder. Depending on its material properties, concrete exposed to fire may experience spalling caused by thermomechanical and thermohydraulic mechanisms. Severe spalling leads to a reduction in the cross-section and exposure of the reinforcement, jeopardizing the load-bearing capacity of the concrete element. The use of blended cements changes the concrete properties which can affect spalling behavior at high temperatures. The link between high temperature and spalling behavior of concrete with blended cements has been investigated in several studies. A review of the existing literature led to the conclusion that the cement type influences the spalling behavior of concrete. However, the relationship does not appear to be clear, as there are contradictions and inconsistencies between the evaluated results. Therefore, further in-depth studies will help to gain a more precise understanding of the effects of blended cements on the spalling behavior of concrete at elevated temperatures. KW - Fire-induced concrete spalling KW - Concrete KW - Blended cements KW - SCM KW - Filler PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635182 DO - https://doi.org/10.1617/s11527-025-02713-x SN - 1359-5997 VL - 58 IS - 5 SP - 1 EP - 21 PB - Springer Science and Business Media LLC AN - OPUS4-63518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezhov, Alexander A1 - Goncharov, A. A1 - Zhutovsky, S. A1 - Kovler, K. A1 - Diesendruck, Ch. E. T1 - The Impact of DNA as a Chemical Admixture for Cementitious Materials N2 - Viscosity modifying agents (VMA) and superplasticizers (SP) are two common macromolecular admixture types for cementitious materials. VMAs are used to stabilize fresh cementitious materials, while SPs are used to disperse them. Most VMAs are bio-based polysaccharides that act in the water phase between particles; while most SPs are synthetic comb polymers, consisting of negatively charged backbones that help their adsorption to the cement particles' surface. The molecular structure of DNA contains elements of VMA – as it is a polysaccharide – and SP – as it is a polyanion. In this study, rheological measurements are used to compare how these three types of macromolecules (VMA, SP, and DNA) affect cementitious materials. It is found that DNA shows the combined effects of VMAs and SPs on cement paste: it lowers yield stress while at the same time maintaining or even increasing its viscosity, which permits reducing water content while avoiding bleeding or segregation of samples. Yet, the presence of DNA has a significant retardation impact on cement hydration, which is also a common side effect of VMAs and SPs. KW - Impact of DNA KW - Viscosity modifying agents (VMA) KW - Superplasticizers (SP) PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638542 DO - https://doi.org/10.1002/admt.202500073 SN - 2365-709X VL - 10 IS - 14 SP - 1 EP - 8 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-63854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bühler, M. M. A1 - Hollenbach, P. A1 - Michalski, A. A1 - Meyer, S. A1 - Birle, E. A1 - Off, R. A1 - Lang, Ch. A1 - Schmidt, Wolfram A1 - Cudmani, R. A1 - Fritz, O. A1 - Baltes, G. A1 - Kortmann, G. T1 - The Industrialisation of Sustainable Construction: A Transdisciplinary Approach to the Large-Scale Introduction of Compacted Mineral Mixtures (CMMs) into Building Construction N2 - Abstract: Increasing demand for sustainable, resilient, and low-carbon construction materials has highlighted the potential of Compacted Mineral Mixtures (CMMs), which are formulated from various soil types (sand, silt, clay) and recycled mineral waste. This paper presents a comprehensive inter- and transdisciplinary research concept that aims to industrialise and scale up the adoption of CMM-based construction materials and methods, thereby accelerating the construction industry’s systemic transition towards carbon neutrality. By drawing upon the latest advances in soil mechanics, rheology, and automation, we propose the development of a robust material properties database to inform the design and application of CMM-based materials, taking into account their complex, time-dependent behaviour. Advanced soil mechanical tests would be utilised to ensure optimal performance under various loading and ageing conditions. This research has also recognised the importance of context-specific strategies for CMM adoption. We have explored the implications and limitations of implementing the proposed framework in developing countries, particularly where resources may be constrained. We aim to shed light on socio-economic and regulatory aspects that could influence the adoption of these sustainable construction methods. The proposed concept explores how the automated production of CMM-based wall elements can become a fast, competitive, emission-free, and recyclable alternative to traditional masonry and concrete construction techniques. We advocate for the integration of open-source digital platform technologies to enhance data accessibility, processing, and knowledge acquisition; to boost confidence in CMM-based technologies; and to catalyse their widespread adoption. We believe that the transformative potential of this research necessitates a blend of basic and applied investigation using a comprehensive, holistic, and transfer-oriented methodology. Thus, this paper serves to highlight the viability and multiple benefits of CMMs in construction, emphasising their pivotal role in advancing sustainable development and resilience in the built environment. KW - Decarbonisation KW - Circular economy KW - Recycled materials KW - Demolition wastes KW - Low-carbon construction KW - Building with earth KW - Compressed earth KW - Rammed earth KW - Sustainable construction PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-583260 DO - https://doi.org/10.3390/su151310677 VL - 15 IS - 13 SP - 1 EP - 25 PB - MDPI AN - OPUS4-58326 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Henning, Ricky A1 - Sturm, Patrick A1 - Geddes, D.A. A1 - Keßler, S. A1 - Walkley, B. A1 - Gluth, Gregor T1 - The influence of curing temperature on the strength and phase assemblage of hybrid cements based on GGBFS/FA blends N2 - Hybrid cements are composites made of Portland cement or Portland clinker and one or more supplementary cementitious materials like slag, fly ash or metakaolin, activated with an alkali salt. To date, their hydration mechanism and the phase formation at various temperatures is insufficiently understood, partly due to the large variability of the raw materials used. In the present study, three hybrid cements based on ground granulated blast furnace slag, fly ash, Portland clinker and sodium sulfate, and an alkali-activated slag/fly ash blend were cured at 10 and 21.5°C, and subsequently analyzed by XRD, 27Al MAS NMR, and TGA. The compressive strength of the hybrid cements was higher by up to 27% after 91-day curing at 10°C, compared to curing at 21.5°C. The experimental results as well as thermodynamic modeling indicate that the differences in compressive strength were related to a different phase assemblage, mainly differing amounts of strätlingite and C-N-A-S-H, and the associated differences of the volume of hydration products. While the strätlingite was amorphous to X-rays, it could be identified by 27Al MAS NMR spectroscopy, TGA and thermodynamic modeling. The microstructural properties of the hybrid cements and the alkali-activated slag/fly ash blend as well as the compatibility between thermodynamic modeling results and experimental data as a function of curing temperature and time are discussed. KW - Hybrid cements KW - Strätlingite KW - Thermodynamic modelling KW - Hydration PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-557767 DO - https://doi.org/10.3389/fmats.2022.982568 SN - 2296-8016 VL - 9 SP - 1 EP - 16 PB - Frontiers AN - OPUS4-55776 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geoerg, Paul A1 - Schumann, Jette A1 - Holl, Stefan A1 - Holl, Maik A1 - Hofmann-Böllinghaus, Anja T1 - The influence of individual impairments in crowd dynamics N2 - The importance of empirical relations to quantify the movement of pedestrians through a facility has increased during the last decades since performance-based design methods became more common. Bottlenecks are of special interest because of their importance for egress routes and as they result in a reduced capacity. The empirical relations as the density-dependent movement speed or flow rate were derived by studies under laboratory conditions, which were usually conducted with populations of homogeneous characteristics forbetter control of influencing variables. If individual characteristics of a crowd become more heterogeneous, individuals were forced to adapt their individual movement and control individual manoeuvring. These unintended interactions lead to a different shape of the fundamental empirical relations. Here, we present results from a movement study under well-controlled boundary conditions in which participants with and without different characteristics of disabilities participated. To consider the effect of different heterogeneities on the capacity of a facility, fundamental diagrams are generated using the Voronoi method. If participants with visible disabilities (such as using assistive devices) are part of a crowd, significant differences relating to the shape of the empirical Relations and the capacities are found. This indicates that the heterogeneity of a Population leads to an increased interpersonal interaction which results in influenced movement characteristics. KW - Engineering egress data KW - Heterogeneity KW - Human behaviour KW - Movement characteristics KW - Pedestrian dynamics PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508943 DO - https://doi.org/10.1002/fam.2789 SN - 0308-0501 VL - 45 IS - 4 SP - 529 EP - 542 PB - Wiley Online Libary CY - New Jersey, USA AN - OPUS4-50894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Gründer, Klaus-Peter A1 - Kadoke, Daniel T1 - The load-bearing behaviour of a reinforced concrete beam investigated by optical measuring techniques N2 - Bending beams and slabs are typical examples for structural elements used for reinforced concrete structures such as bridge girders, T-beams and bridge decks. Their strength related failure modes at maximum loading can be divided into bending and shear failure. The failure of beams loaded in bending can occur with or without indication. Therefore, conventional design concepts aim on failure modes with sufficient indication (e.g. large deflections or cracks), as it occurs in the case of secondary flexural compression failure. These indicating factors can also be used for Structural Health Monitoring (SHM) of civil infrastructure systems (e.g. bridges) to identify structural changes. In this context, non-destructive testing (NDT) methods offer different techniques for measuring deflections or crack formation and opening. However, profound knowledge on the determining failure modes of bending beams and their detection by NDT methods is required for the reliable application of SHM. Different NDT methods have been used in this study for analysing the load-bearing behaviour of a reinforced concrete beam in bending. The different measuring techniques are briefly described and their applicability is discussed by means of experimental results. For this purpose, the load-bearing behaviour of a reinforced concrete beam having a span of 2.75 m was investigated in a four-point bending flexural test at laboratory scale. The focus is on the characterization of determining failure modes by optical NDT and the comparison with classical measuring techniques (e.g. deformation measurements by displacement transducers). The bending beam was equipped with two single-mode (SM) sensor fibres. One fibre served as Distributed Optical Fibre Sensor (DOFS), whereas the other fibre contained Fibre Bragg Grating (FBG) sensors. In addition, optical deformation measurements using Digital Image Correlation (DIC) and Stereophotogrammetry (SP) were conducted. KW - Concrete beam KW - Bending KW - Digital image correlation KW - Stereophotogrammetry KW - Distributed fibre optic sensor KW - Fibre bragg grating PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-524762 DO - https://doi.org/10.1617/s11527-021-01699-6 VL - 54 IS - 3 SP - Article 102 PB - Springer AN - OPUS4-52476 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 - Strommer, Bettina A1 - Schulze, Dietmar A1 - Schartel, Bernhard A1 - Böhning, Martin T1 - The quantification of anisotropy in graphene/natural rubber nanocomposites: Evaluation of the aspect ratio, concentration, and crosslinking N2 - In the processing of nanocomposites, high shear stresses at elevated tempera-tures orient two-dimensional nanoparticles like graphene. This orientationleads to anisotropic mechanical, thermal or barrier properties of the nanocom-posite. This anisotropy is addressed in this study by comparing graphene (few-layer graphene, FLG) with a nanoscaled carbon black (nCB) at a filler contentof 3 phr, by varying the vulcanization, and by comparing different FLG con-tents. Transmission electron microscopy gives insight into the qualitative ori-entation in the nanocomposite with FLG or nCB. The storage moduli paralleland normal to the orientation reveal the direction dependency of reinforce-ment through dynamic mechanical analysis (DMA). Dimensional swellingmeasurements show a restriction of the expansion parallel to the FLG orienta-tion, and an increased expansion normal to the orientation. The vulcanizationsystem and crosslinking determine the respective level of property values, andhigher crosslinking densities increase the anisotropy in DMA resulting invalues of up to 2.9 for the quantified anisotropy factor. With increasing FLGcontent, the anisotropy increases. A comparison of the results reveals swellingmeasurements as the most suitable method for the determination of anisot-ropy. Compared to recent literature, the presented processing induces higheranisotropy, leading to higher reinforcing effects in the direction of orientation KW - Natural rubber KW - Graphene KW - Nanocomposite KW - Mechanical properties KW - Swelling PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-571522 DO - https://doi.org/10.1002/app.53753 SN - 1097-4628 VL - 140 IS - 16 SP - 1 EP - 15 PB - Wiley online library CY - Hoboken, New Jersey (USA) AN - OPUS4-57152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - von Werder, Julia A1 - Simon, Sebastian A1 - Gardei, André A1 - Fontana, P. A1 - Meng, Birgit T1 - Thermal and hydrothermal treatment of UHPC: influence of the process parameters on the phase composition of ultra-high performance concrete N2 - Several studies show that thermal and hydrothermal treatment can further improve the excellent properties of UHPC in terms of mechanical strength and durability. While for the thermal treatment the increase in strength is attributed to an intensified pozzolanic and hydraulic reaction, for the hydrothermal treatment previous studies accredited it mostly to the formation of tobermorite. In the presented study thermal and hydrothermal treatment of UHPC samples was systematically varied and the phase formation analysed related to the strength development of a reference sample cured for 28 days in water. For the thermal treatment the results show that the strength increase depends on the protection against desiccation and can be ascribed to an improved pozzolanic reaction of the siliceous fillers. To achieve a significant enhancement of strength, a pre-storage time of few days and a long dwell time at elevated temperature/pressure are required. For the hydrothermal treatment already heating the specimens up to 185 °C in saturated steam followed by an immediate cooling leads to a substantial increase in compressive strength. Pre-storage time did not affect the result as far as a minimum of several hours is guaranteed. The improved performance is due to an increase in the pozzolanic and hydraulic reaction. Surprisingly, tobermorite was only found within a very thin layer at the surface of the sample, but not in the bulk. Sulphate and aluminium stemming from the decomposition of the ettringite are bound in the newly formed phases hydroxylellestadite and hydrogarnet. KW - UHPC KW - Thermal treatment KW - Hydrothermal treatment KW - Compressive strength KW - Phase development KW - Durability KW - Tobermorite KW - Hydroxylellestadite KW - Hydrogarnet PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523402 DO - https://doi.org/10.1617/s11527-021-01633-w SN - 1871-6873 SN - 1359-5997 VL - 54 IS - 1 SP - Article 44 PB - Springer Nature AN - OPUS4-52340 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pittrich, Tim A1 - Jansen, Daniel A1 - Weise, Frank A1 - Stelzner, Ludwig A1 - Dehn, Frank T1 - Thermal decomposition in blended cement systems and its effect on fire-induced concrete spalling: Insights from XRD and TGA N2 - Blended cements are gaining increasing popularity due to their lower CO2-footprint in comparison to ordinary Portland cement (OPC). However, this growing use raises the potential risk of buildings made with blended cement concrete being exposed to fire, which can lead to heavy damages caused by explosive concrete spalling. It has already been shown that the cement type strongly influences the fire-induced concrete spalling and the thermally induced moisture transport, however, to understand the mechanisms behind these findings the thermal decomposition behavior of the cementitious matrix must be investigated more systematically. Therefore, the phase content of three blended cement pastes (CEM II/A-LL, CEM III/A and CEM II/B-Q) was studied in comparison with a Portland cement paste (CEM I) after temperature exposure to 20 ◦C, 105 ◦C, 300 ◦C and 500 ◦C. Clear differences in the initial phase composition and their dehydration behavior between the individual cement types were recognized. In conclusion, blended cements showed lower amounts of AFt and AFm phases and additionally lower amounts of portlandite and C-(A)-S-H were found in CEM III/A and CEM II/B-Q pastes. The results suggest that higher AFt and AFm contents in CEM I, which are associated with greater water release at relatively low temperatures may ultimately reduce the spalling risk. Furthermore, C-(A)-S-H in CEM III/A and CEM II/B-Q showed increased thermal stability and large amounts of non-hydrated phases were found in every blended cement paste. Both of those aspects might contribute to thermomechanical spalling and the overall increased spalling susceptibility observed in blended cement concrete. KW - Fire concrete spalling KW - High temperatures KW - Blended cements KW - Dehydration KW - XRD KW - TGA PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653698 DO - https://doi.org/10.1016/j.cscm.2026.e05784 SN - 2214-5095 VL - 24 SP - 1 EP - 14 PB - Elsevier Ltd. AN - OPUS4-65369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wagner, Jan A1 - Dudziak, Mateusz A1 - Falkenhagen, Jana A1 - Rockel, Daniel A1 - Reimann, H.-A A1 - Schartel, Bernhard T1 - This is the way: An evidence based route to phytic-acid–based flame retardant poly(lactide acid) N2 - A systematic sequence of materials was investigated to develop phytic-acid (Phyt)–based flame retarded poly (lactide acid) (PLA), while factoring in molecular weight (MW), crystallinity and mechanical properties. Synergistic approaches were developed based on combinations with lignin and expandable graphite (EG), as well as by applying different Phyt salts of melamine (Mel), piperazine (Pip), and arginine (Arg). Compounds were twin screw extruded, injection molded, hot pressed and investigated with thermal analysis, size exclusion chromatography, infrared spectroscopy, tensile testing, limited oxygen index (LOI), UL 94, cone calorimeter, and scanning electron microscope. 16.7 wt.% flame retardant (FR) slightly enhances crystallization while MW remains unchanged in PLA Phyt Arg and PLA Phyt Mel. LOI was improved to 43.7 vol.% for PLA Phyt Arg, UL 94 V0 achieved for PLA Phyt Pip. Cone calorimeter results show total heat evolved reduced by 14 %, maximum average rate of heat emission 43 % lower, and peak heat release rate reduced by 50 % for PLA Phyt Mel. Phyt Mel combined with EG increased the char yield of PLA to 20 wt.% and 15.5 wt.% at 600 and 900 ◦C, respectively. Phyt is exploited to enhance char yield, stabilize the intumescent char, and lower the apparent effective heat of combustion. The combination of Phyt Mel and EG was proposed as an efficient FR for PLA via an evidence based developing route. KW - Polylactide acid KW - Intumescent flame retardant KW - Phosphorous flame retardant KW - Phytic acid KW - Expandable graphite KW - Melamine PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626395 DO - https://doi.org/10.1016/j.polymdegradstab.2025.111242 SN - 1873-2321 SN - 0141-3910 VL - 234 SP - 1 EP - 14 PB - Elsevier Ltd. AN - OPUS4-62639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dudziak, Mateusz A1 - Dural, Esra A1 - Dey, R. A1 - Ullrich, M. S. A1 - Huth, Christian A1 - Thomson, C. A1 - Schartel, Bernhard T1 - Together We Can: Synergistic Flame Retardancy by Melamine Polyphosphate and Phosphorylated Microalgae in Polylactide Biocomposites N2 - A strategy for enhancing the sustainable flame retardancy of polylactide (PLA) composites by partially replacing melamine polyphosphate (MPP), a commercial flame retardant proposed for PLA, with wastewater polyphosphate-enriched microalgae (P-Algae) has been explored. The incorporation of P-Algae at a 1:1 ratio with MPP leads to a notable synergistic effect, surpassing the expected additive behavior of the individual components. Comprehensive characterization encompassing thermogravimetric analysis coupled with FTIR, pyrolysis combustion flow calorimeter (PCFC), cone calorimeter, oxygen index (LOI), UL-94 tests, and rheological measurements—demonstrates that the presence of this biomaterial can significantly enhance flame retardant performance. Replacing 50% of MPP with P-Algae in PLA resulted in a 17% reduction in peak heat release rate (pHRR) and maintained a V-0 rating in UL-94 testing. The use of P-Algae does not compromise the flame retardancy of PLA but rather contributes positively, offering a promising path toward more sustainable flame-retardant systems. By leveraging naturally derived biomass, this approach aligns with the growing demand for novel eco-friendly technologies in polymer engineering. Insights into an innovative renewable additive as a functional and effective component in flame-retardant biocomposites have been achieved. KW - Flame retardancy KW - Melamine polyphosphate KW - Phosphorus- enriched microalgae KW - Polylactide PLA KW - Synergism PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-640539 DO - https://doi.org/10.1002/pat.70350 SN - 1099-1581 SN - 1042-7147 VL - 36 IS - 9 SP - e70350 PB - John Wiley & Sons Ltd. AN - OPUS4-64053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rütters, H. A1 - Fischer, S. A1 - Le, Quynh Hoa A1 - Bettge, Dirk A1 - Bäßler, Ralph A1 - Maßmann, J. A1 - Ostertag-Henning, C. A1 - Wolf, J. L. A1 - Pumpa, M. A1 - Lubenau, U. A1 - Knauer, S. A1 - Jaeger, P. A1 - Neumann, A. A1 - Svensson, K. A1 - Pöllmann, H. A1 - Lempp, C. A1 - Menezes, F. F. A1 - Hagemann, B. T1 - Towards defining reasonable minimum composition thresholds – Impacts of variable CO2 stream compositions on transport, injection and storage N2 - To set up recommendations on how to define “reasonable minimum composition thresholds” for CO2 streams to access CO2 pipeline networks, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the CCS chain. All investigations were based on a generic “CCS cluster scenario” in which CO2 streams captured from a spatial cluster of eleven emitters (seven fossil-fired power plants, two cement plants, one refinery and one steel mill) are collected in a regional pipeline network. The resulting CO2 stream (19.78 Mio t impure CO2 per year) is transported in a trunk line (onshore and offshore) and injected into five generic replicate storage structures (Buntsandstein saline aquifers) offshore. Experimental investigations and modeling of selected impacts revealed beneficial as well as adverse impacts of different impurities and their combinations. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the considered variable compositions and mass flow rates were observed. We recommend to define minimum composition thresholds for each specific CCS project through limiting i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of concentrations of critical impurities, and defining impurity combinations to be avoided. KW - Impurities KW - CO2 quality KW - Pipeline network KW - Whole-chain CCS scenario KW - Recommendations PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-543004 DO - https://doi.org/10.1016/j.ijggc.2022.103589 SN - 1750-5836 VL - 114 SP - 1 EP - 14 PB - Elsevier CY - New York, NY AN - OPUS4-54300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sittner, Jonathan A1 - Götze, Jens A1 - Müller, Axel A1 - Renno, Axel D. A1 - Ziegenrücker, René A1 - Pan, Yuanming T1 - Trace element analysis and luminescence behavior of quartz in pegmatites of the Tørdal Region, Norway N2 - This publication presents a study on the mineral chemistry and luminescence properties of quartz samples from pegmatites of the Tørdal region in Norway. A total of 12 samples were analyzed using Secondary Ion Mass Spectrometry (SIMS), Electron Paramagnetic Resonance Spectroscopy (EPR), and Cathodoluminescence (CL) to gain insights into their trace element concentration and distribution as well as their luminescence behavior. The samples are characterized by different Cl emissions at 450 nm, 500 nm 650 nm and an additional shoulder at 390 nm, which is only partially visible due to the absorption of the glass optics. Of these luminescence bands, the 500 nm band is the most dominant in most samples and it is characterized by an initial blue-green luminescence, which is not stable under electron irradiation. Moreover, it is characterized by a heterogeneous distribution within the samples. This luminescence can be mostly assigned to [AlO4/M+]0 defects, with charge compensation mostly achieved by Li+. Analyses by EPR spectroscopy prove the dominance of structurally bound Al, Li, and Ti ions in the investigated samples. Further analyses using SIMS mapping demonstrate that Na and K are mainly bound to micro fractures or inclusions, suggesting a limited role in the compensation of the luminescence centers. Additionally, the SIMS mappings show that some samples contain Al-rich clusters of 10 to 20 µm in diameter, whereas other trace elements are characterized by a homogeneous distribution. These clusters correspond to bright luminescence areas in size and shape and could potentially indicate H+ compensated [AlO4/M+]0 defects. KW - Quartz KW - Trace elements KW - SIMS KW - Cathodoluminescence KW - EPR KW - Tørdal KW - Pegmatite PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612529 DO - https://doi.org/10.1016/j.chemgeo.2024.122427 VL - 670 SP - 1 EP - 15 PB - Elsevier BV AN - OPUS4-61252 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rockel, Daniel A1 - Sanchez Olivares, G. A1 - Calderas, F. A1 - Schartel, Bernhard T1 - Two heads are better than one: Aluminum trihydroxide / phosphorous flame retardant combination in natural waste fiber biocomposites N2 - Future polymeric materials that replace fossil fuel-based engineering plastics demand the use of renewable sources as well as the implementation of key properties such as flame retardancy, processing, and mechanical properties. This study focuses on the combination of aluminum trihydroxide (ATH) and phosphorus-based flame retardants in compositable thermoplastic starch reinforced with sustainable multifunctional leather waste fibers. The flame retardants engender different flame-retardant modes of action, improving overall performance when combined. The partial substitution of ATH with phosphorous flame retardant allowed a reduction in flame retardant loading. Materials with 90 phr of ATH reached a limiting oxygen index of 31.5 vol.-% and a UL-94 rating of V-1, whereas the combination of 73 phr ATH and 7 phr of diphenyl ocytyl phosphate achieved a V-0 rating and a slightly reduced peak of heat release rate. This study demonstrates the potential of multicomponent systems implementing waste fiber–reinforced biocomposites. KW - Biocomposites KW - Flame retardancy KW - Phosphorous flame retardants KW - Synergism KW - Sustainability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-639084 DO - https://doi.org/10.1016/j.polymertesting.2025.108938 SN - 0142-9418 SN - 1873-2348 VL - 150 SP - 1 EP - 17 PB - Elsevier Ltd. AN - OPUS4-63908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stohl, Leonie A1 - Tonon, Chiara A1 - Cook, Jake A1 - Gorbushina, Anna A1 - Dehn, Frank A1 - von Werder, Julia A1 - Manninger, Tanja T1 - Understanding bioreceptivity of concrete: material design and characterization N2 - The climate crisis is driving an increasing demand for ecologically oriented concepts. In the building sector, this demand includes not only the use of environmentally friendly materials but also the greening of urban areas. One promising approach is the development of bioreceptive concrete façades, which support the growth of green biofilms directly on their surfaces. These innovative façades are anticipated to deliver benefits comparable to those of macroscopically greened façades, such as enhanced biodiversity and improved air quality, while offering the advantages of being more self-sustaining and stable systems once fully established. However, the development of bioreceptive concrete presents substantial challenges. Due to the interdisciplinarity and novelty of this field, standardized methods for material characterization and bioreceptivity assessment are currently lacking. This study proposes an approach for evaluating surface properties crucial for bioreceptivity, developed on differently structured samples of ultra-high-performance concrete (UHPC). Existing methods and standards from concrete technology are critically reviewed and, where necessary, modified to meet the unique requirements of measuring bioreceptive material properties. Special attention is given to the surface pH value and water retention characteristics, as these are essential for promoting microbial growth and ensuring the long-term stability of green biofilms. The observed surface characteristics vary according to the imprinted surface structures, offering a spectrum of material properties and enabling the evaluation of their impact on bioreceptivity. The findings presented form the foundation for subsequent laboratory weathering experiments, which will be discussed in a complementary publication. KW - Novel methods KW - Bioreceptivity testing PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655023 DO - https://doi.org/10.1617/s11527-025-02863-y SN - 1359-5997 VL - 58 SP - 1 EP - 18 PB - Springer Science and Business Media LLC AN - OPUS4-65502 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stohl, Leonie A1 - Manninger, Tanja A1 - Dehn, Frank A1 - von Werder, Julia T1 - Understanding bioreceptivity of concrete: material design and characterization N2 - The climate crisis is driving an increasing demand for ecologically oriented concepts. In the building sector, this demand includes not only the use of environmentally friendly materials but also the greening of urban areas. One promising approach is the development of bioreceptive concrete façades, which support the growth of green biofilms directly on their surfaces. These innovative façades are anticipated to deliver benefits comparable to those of macroscopically greened façades, such as enhanced biodiversity and improved air quality, while offering the advantages of being more self-sustaining and stable systems once fully established. However, the development of bioreceptive concrete presents substantial challenges. Due to the interdisciplinarity and novelty of this field, standardized methods for material characterization and bioreceptivity assessment are currently lacking. This study proposes an approach for evaluating surface properties crucial for bioreceptivity, developed on differently structured samples of ultra-high-performance concrete (UHPC). Existing methods and standards from concrete technology are critically reviewed and, where necessary, modified to meet the unique requirements of measuring bioreceptive material properties. Special attention is given to the surface pH value and water retention characteristics, as these are essential for promoting microbial growth and ensuring the long-term stability of green biofilms. The observed surface characteristics vary according to the imprinted surface structures, offering a spectrum of material properties and enabling the evaluation of their impact on bioreceptivity. The findings presented form the foundation for subsequent laboratory weathering experiments, which will be discussed in a complementary publication. KW - Bioreceptivity KW - Concrete KW - Biofilm PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-648180 DO - https://doi.org/10.1617/s11527-025-02863-y SN - 1359-5997 VL - 58 IS - 10 SP - 1 EP - 12 PB - Springer Science and Business Media LLC AN - OPUS4-64818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stohl, Leonie A1 - Tonon, Chiara A1 - Cook, Jake A1 - Gorbushina, Anna A1 - Dehn, Frank A1 - von Werder, Julia T1 - Understanding bioreceptivity of concrete: realistic and accelerated weathering experiments with model subaerial biofilms N2 - Vertical greening systems are a promising solution to the increasing demand for urban green spaces, improving environmental quality and addressing biodiversity loss. This study facilitates the development microbially greened algal biofilm facades, which offer a low maintenance vertical green space. The study focuses on concrete as a widely used building material and explores how physical surface characteristics impact its bioreceptive properties. Concrete samples, produced from the same mix but differing in surface structure, were subjected to a laboratory weathering experiment to assess their bioreceptivity. A novel inoculation method was employed, involving a single initial inoculation with either alga ( Jaagichlorella sp.) alone, or a model biofilm consisting of a combination of the alga ( Jaagichlorella sp.) with a fungus ( Knufia petricola). The samples underwent four months of weathering in a dynamic laboratory setup irrigated with deionized water to observe subaerial biofilm attachment and growth. The formation of subaerial biofilms was monitored with high resolution surface imaging, colorimetric measurements and Imaging Pulse Amplitude Modulated Fluorometry (Imaging PAM-F), with Imaging PAM-F proving the most effective. Statistical analysis revealed that by impacting surface pH value and water retention capability, surface structures significantly influence microbial growth and that the concrete’s bioreceptivity can be influenced through thoughtful design of the materials surface. The inoculation of algae combined with a fungus facilitated the formation of a stable subaerial biofilm, enabling algae to colonize a surface structure that it could not colonize alone. This finding highlights the importance of modelling synergistic interactions present in natural biofilms. KW - Bioreceptivity KW - Concrete KW - Biofilm PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653105 DO - https://doi.org/10.1617/s11527-025-02864-x SN - 1359-5997 VL - 59 IS - 2 SP - 1 EP - 18 PB - Springer Science and Business Media LLC AN - OPUS4-65310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Sebastian A1 - Gluth, Gregor ED - Rossignol, S. ED - Gluth, Gregor T1 - Unraveling the hardening mechanism during laser-induced slip casting of lithium aluminate-microsilica slurry N2 - Additive manufacturing (AM) of alkali-activated materials is a promising method for producing ceramic precursors, construction elements and other parts. A recently introduced AM process is laser-induced slip casting of lithium aluminate/microsilica slurries, which yields parts with excellent mechanical strengths. To clarify the underlying mechanisms, μ-Raman spectroscopy was applied to parts produced by the process, and the dissolution and hydration of lithium aluminate was studied inter alia using conventional and in-situ X-ray diffraction. The results show that significant dissolution of lithium aluminate occurs, particularly at increased temperatures during laser interaction, which leads to an increase of pH and precipitation of an akopovaite-like Li-Al-CO3 layered double hydroxide. The increase of the pH is likely to induce dissolution of the microsilica and possibly formation of a hydrous lithium aluminosilicate gel. These observations explain the strength evolution of the studied parts and can also aid the development and improvement of related AM methods. KW - Alkali-activated materials KW - Additive manufacturing KW - Laser-induced slip casting KW - Lithium KW - Layered double hydroxide PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520557 DO - https://doi.org/10.1016/j.oceram.2021.100060 SN - 2666-5395 VL - 5 IS - Special issue: Alkali-activated materials and geopolymers in ceramics and beyond SP - 1 EP - 7 PB - Elsevier CY - Amsterdam AN - OPUS4-52055 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jauregui Rozo, Maria A1 - Sunder, S. A1 - Tabaka, Weronika A1 - Klaffke, Benjamin A1 - Ruckdäschel, H. A1 - Schartel, Bernhard T1 - Unveiling aluminum diethyl phosphinate dual identity: Transfer from epoxy resins to glass fiber-reinforced composites N2 - This study examines the transfer of the flame-retardant aluminum diethyl phosphinate (AlPi) from epoxy resins to composites and the impact of AlPi on fire behavior and fire stability. Further, the effects of different particle sizes and the addition of zinc hydroxy stannate (ZHS) and inorganic silicate (InSi) are investigated. The research provides a detailed analysis of the fire behavior, fire stability, pyrolysis, flame-retardant modes of action, and flame retardancy index. Interestingly, the particle sizes did not significantly affect the flammability, fire behavior, or fire stability in the systems investigated. AlPi acts primarily in the gas phase, releasing phosphorus that yields flame inhibition. Adding glass fibers (GFs) to the epoxy resin boosts the flame retardancy in the condensed phase, reducing the heat release rate (HRR), total heat release (THR), and peak heat release rate (PHRR) by about 60%. This improvement is largely due to replacing fuel and forming a protective layer during burning. Despite the differences between thermoset and composite, the study demonstrates an effective transfer of flame-retardant properties from epoxy resins to fiber-reinforced composites, significantly enhancing the flame retardancy performance in both material systems. KW - Aluminum diethyl phosphinate KW - Epoxy resins KW - Fire behavior KW - Fire stability KW - Gas-phase active KW - Glass fiber-reinforced composites KW - Particle sizes PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643013 DO - https://doi.org/10.1002/pc.29911 SN - 1548-0569 SN - 0272-8397 VL - 46 IS - 14 SP - 12981 EP - 12999 PB - Wiley AN - OPUS4-64301 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Unveiling Effects of Biodiesel and Diesel on Environmental Stress Cracking of PE-HD N2 - The behavior of high‐density polyethylene with respect to resistance against environmental stress cracking (ESC) is usually regarded as an inherent material property being specific for respective types of PE‐HD and tested using standardized methods, conditions, and also standard testing liquids (usually aqueous surfactant solutions). On the other hand, for practical applications the ESC behavior of those polymeric materials, commonly used for pipes or containers, in contact with other liquids (e.g., fuels) is often of relevant interest, but for a reasonable assessment, where consistent benchmark data for a direct comparison are often missing, it is essential to determine the actually prevailing failure mode and classify it related to crack propagation or other mechanisms. Using the well‐established Full Notch Creep Test, which favorably allows for a detailed microscopic fracture surface analysis after failure, the behavior of two typical PE‐HD types for container applications is investigated in biodiesel and diesel and compared to a standard surfactant solution. This enables a clear identification of characteristic features of the interaction of biodiesel and diesel as sorptive fuels in contact with the polymer, revealing the complex interplay of sorption and plasticization as well as ESC inducing effects on PE‐HD, which could be clearly shown for both fuels. KW - Biodiesel KW - Confocal laser scanning microscopy (LSM) KW - Diesel KW - Full notch creep test (FNCT) KW - Plasticization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650525 DO - https://doi.org/10.1002/pen.70239 SN - 0032-3888 SP - 1 EP - 16 PB - Wiley CY - Hoboken (NJ) AN - OPUS4-65052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fürst, Richard A1 - Fürst, E. A1 - Vlach, T. A1 - Repka, J. A1 - Pokorny, M. A1 - Mozer, V. T1 - Use of Cement Suspension as an Alternative Matrix Material for Textile-Reinforced Concrete N2 - Textile-reinforced concrete (TRC) is a material consisting of high-performance concrete (HPC) and tensile reinforcement comprised of carbon roving with epoxy resin matrix. However, the problem of low epoxy resin resistance at higher temperatures persists. In this work, an alternative to the epoxy resin matrix, a non-combustible cement suspension (cement milk) which has proven stability at elevated temperatures, was evaluated. In the first part of the work, microscopic research was carried out to determine the distribution of particle sizes in the cement suspension. Subsequently, five series of plate samples differing in the type of cement and the method of textile reinforcement saturation were designed and prepared. Mechanical experiments (four-point bending tests) were carried out to verify the properties of each sample type. It was found that the highest efficiency of carbon roving saturation was achieved by using finer ground cement (CEM 52.5) and the pressure saturation method. Moreover, this solution also exhibited the best results in the four-point bending test. Finally, the use of CEM 52.5 in the cement matrix appears to be a feasible variant for TRC constructions that could overcome problems with its low temperature resistance. KW - Textile-reinforced concrete KW - High-performance concrete KW - Carbon fibers KW - Cement matrix PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527100 DO - https://doi.org/10.3390/ma14092127 SN - 1996-1944 VL - 14 IS - 9 SP - 2127 PB - MDPI CY - Basel AN - OPUS4-52710 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Long, Lijia A1 - Alcover, I. F. A1 - Thöns, Sebastian T1 - Utility analysis for SHM durations and service life extension of welds on steel bridge deck N2 - Optimization of the duration of Structural Health Monitoring (SHM) campaigns is rarely performed. This article provides a utility-based solution to posteriorly determine: i) optimal monitoring Durations and ii) the extension of the service life of the welds on a steel bridge deck. The approach is Illustrated with a case study focusing on remaining fatigue life estimation of the welds on the orthotropic steel deck of the Great Belt Bridge, in Denmark. The identification of the optimal monitoring duration and the decision about extending the service life of the welds are modelled by maximizing the expected benefits and minimizing the structural risks. The results are a parametric analysis, mainly on the effect of the target probability, benefit, cost of failure, cost of rehabilitation, cost of monitoring and Discount rate on the posterior utilities of monitoring strategies and the choice of service life considering the risk variability and the costs and benefits models. The results show that the decision on short-term monitoring, i.e., 1 week every six months, is overall the most valued SHM strategy. In addition, it is found that the target probability is the most sensitive parameter affecting the optimal SHM Durations and service life extension of the welds. KW - Fatigue KW - Monitoring strategy KW - Orthotropic steel deck KW - Structural health monitoring KW - Utility and decision theory PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-521719 DO - https://doi.org/10.1080/15732479.2020.1866026 SN - 1573-2479 VL - 18 IS - 4 SP - 492 EP - 504 PB - Taylor Francis Online AN - OPUS4-52171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -