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upMIN 100 – upcycling of mineral construction and demolition waste to substitute natural aggregates in earthen building materials
No full textThe construction sector is one of the most resource-intensive sectors in Germany and is responsible for 40 % of CO2 emissions. Around 517 million tons of mineral raw materials are required annually for the construction of buildings in Germany. At the same time, mineral construction waste was the largest material flow at 229.3 million tons (2020). The rates of construction and demolition waste (CDW) recycling have increased since 2000, especially for mineral waste. Nevertheless, the majority of recycled aggregates are used in technically largely unregulated applications (e.g. road construction). This downcycling leads to a loss of valuable resources for technically and economically valuable applications. The upMIN 100 research project is investigating the question of whether and to what extent recycled CDW is suitable as an additive an binder in earthen building materials. The focus is placed on grain sizes of < 2 mm, which are currently predominantly landfilled, as there are at present no regulations for their use in building products. The soil matrix of earthen building materials however, naturally contains of different grain sizes, whith < 2mm – 0,063 for aggregates and < 0.063 mm as a binder. Therefore, the focused grain sizes (sand, clay and silt) could have a high usage potential. In order to enable the use of CDW, the technical feasibility must be ensured, quality requirements for source materials (e.g. threshold values for pollutants in terms of health and environmental compatibility and hazardous substances) and permissible proportions of recycled aggregates must be defined. Two different building material developments (earth blocks and -plaster)were used to assess both, the technical feasibility as well the pollutant content of the recycled aggregate and its final emissions into the indoor air. For both materials two mixtures could be established, that also meet the mechanical specifications according to the DIN standard, such as the compressive strength. A method was developed to design material mixtures with a high amount of CDW that comply with the defined limit values. The mixtures reached a recycling rate of 28 % with high mechanical properties and 70 % with minimum strength requirements
Reusable data: putting the “Arr” in FAIR
No full textThis talk demonstrates how to apply FAIR principles to data from actual scientific investigations. The reasons and practical benefits of FAIR data are highlighted. Several levels of reusability are discussed, i.e. the “trust me”-level, the “I’ll not need to repeat my measurement”-level, and the “you’ll not need to repeat my measurements”-level. Practical FAIR datafiles are explored and their information content highlighted
Pyrazinamide-Pimelic Acid Cocrystals: A Mechanochemical and Thermal Study
No full textCocrystals represent a promising class of crystalline materials, offering a wide potential for physico-chemical property alteration of chemical compounds, such as their solubility, by cocrystallizing the targeted compound with another solid material. In the present study, we investigated the cocrystal system between the anti-tuberculosis drug pyrazinamide (PZA) and pimelic acid (PA) by thermal characterization and milling conditions of mechanochemical synthesis. Thermal treatment resulted in the formation of a eutectic between the compounds PZA and PA. Furthermore, irreversible separation of the cocrystal occurred upon melting. This finding indicated low stability of the cocrystal and the necessity of mechanochemical synthesis for cocrystal formation. The mechanochemical synthesis parameters were elucidated by investigating the temperature effect while milling and the role of pre-milling the coformer PA using in-situ monitoring techniques. The polymorphism of PA, influenced by temperature and pre-milling, exhibited a substantial impact on the kinetics of cocrystallization. This finding underscores the significance of coformer polymorphism as an additional factor in mechanochemical cocrystallization reactions
Lösungsansätze für neue Herausforderungen im konstruktiven baulichen Brandschutz
No full textDer Klimawandel und die zunehmende Ressourcenknappheit stellen Herausforderungen dar, die in Zukunft grundlegende Anpassungen in der Art des Umgangs mit Rohstoffen, Energie und des Wirtschaftens an die Gesellschaft stellen werden. In der Leichtbaustrategie der Bundesregierung wird zusammenfassend festgestellt, dass der fortschreitende Klimawandel Technologien erfordert, die die Transformation der Wirtschaft, eine ressourcenschonende Wertschöpfung und eine nachhaltige und resiliente Rohstoffversorgung sicherstellen. Aus diesen für alle Wirtschaftszweige sehr allgemein formulierten Anforderungen und vor dem Hintergrund eines wachsenden Bedarfs schnell verfügbarer Bausubstanz, lassen sich konkrete Anforderungen für das Bauwesen ableiten. Es geht um die Reduktion des Ressourcenverbrauchs für die Errichtung und den Betrieb neuer Gebäude sowie die Nach- und Weiternutzung bestehender Bausubstanz.
In der Bundesanstalt für Materialforschung und -prüfung (BAM) wurde im Themenfeld Infrastruktur das Aktivitätsfeld Leichtbau ins Leben gerufen, das die Forschungsaktivitäten zum Leichtbau bündelt. Im vorliegenden Beitrag werden ausgewählte Projekte in Bezug auf den konstruktiven baulichen Brandschutz vorgestellt und die besonderen Herausforderungen verdeutlicht sowie die daraus abgeleiteten technischen Lösungsmöglichkeiten aufgezeigt.
Als Beispiel einer Bauweise mit höchstmöglicher Effizienz in der Materialausnutzung sowie exzellenter Recyclingfähigkeit des Werkstoffs wird im Abschnitt „Einsatz reaktiver Brandschutzsysteme auf Stahlzuggliedern mit Vollprofil“ gezeigt, wie der Feuerwiderstand von Stahlzuggliedern mit minimalem Materialaufwand sichergestellt werden kann. Anhand des Beispiels der „Alten Aktienspinnerei“ verdeutlicht sich die Relevanz der Methode für die Nachnutzung historischer Bausubstanz.
Im Abschnitt „In situ Überprüfung des Feuerwiderstands von Stahltragwerken mit gealterten reaktiven Brandschutzsystemen“ wird gezeigt, wie in Zukunft die minimalinvasive Überprüfung der Wirksamkeit bereits über Jahrzehnte in Nutzung befindlicher reaktiver Brandschutzsysteme (RBS) ermöglicht wird. Dies bildet die Grundvoraussetzung für eine Weiternutzung sowie möglicherweise erforderliche Instandsetzung auch nach Überschreitung der ursprünglich vorgesehenen Nutzungsdauer des RBS anhand einer quantitativen Aussage zum noch vorhandenen Feuerwiderstand.
Eine wichtige Strategie im Betonbau zur Verringerung des CO2-Ausstoßes wird im Abschnitt „Feuerwiderstand von Leichtbaukonstruktionen aus vorgespanntem Carbonbeton“ vorgestellt. Das Verbundforschungsvorhaben verfolgt die Entwicklung eines neuen Deckensystems aus vorgespanntem Carbonbeton. Die angestrebte Leichtbauweise verringert den Einsatz von Zement durch Minimierung des erforderlichen Betonvolumens. Um einen möglichst dünnen Deckenspiegel zu erzeugen ist eine Reduzierung der Betondeckung erforderlich, weshalb für den Brandfall Maßnahmen zu ergreifen sind, die die Erwärmung der Carbonbewehrung und die damit einhergehende Degradation des Materials begrenzen. In diesem Zusammenhang sind auch wirksame Strategien zur Eindämmung von Beton-abplatzungen zu entwickeln.
Abschließend wird im Abschnitt „Gebäude in Stahl-Modulbauweise mit selbstaussteifenden Raumzellen“ herausgearbeitet, wie diese Bauweise zukünftig noch effizienter werden kann, indem eine Nachweismöglichkeit der aussteifenden Wände in Leichtbauweise für den Brandfall geschaffen wird
Enhanced Fe and Ni bonded NbC Laser Surface Engineered based Hardmetals: Alternative Cutter Materials for Electric Vehicle Applications
No full textThe efforts to substitute both tungsten carbide (WC) and cobalt (Co) has gained prominence in recent years due to the classification of Co as a carcinogen and the classification of Co and W as critical raw materials in the EU as well as within regulations of the U.S. National Toxicology Program. In this study, substitution of both WC and Co with advanced hardmetals consisting of NbC with Ni and Fe-based metal binders are investigated for their use of machining of metals used electric vehicle manufacturing. The developed NbC-Ni/Fe based hardmetals employ a Machining Property Led Tailored Design (MPLTD) approach. This reverse engineering strategy uses data from machining performance to guide the development of microstructural, mechanical, and behavioral properties. Four advanced NbC-based hardmetals were produced, two with Ni-based binders and two with Fe-based binders, along with two reference materials for comparison (WC-Co and straight NbC-12Ni). Hardmetals were characterized using field emission scanning electron microscopy (FE-SEM), annular dark-field scanning transmission electron microscopy (ADF-STEM), Vickers hardness, fracture toughness, and elastic moduli. Cutting tool inserts were manufactured from the developed hardmetals and enhanced using femto-second laser surface engineering. The inserts’ performance was evaluated through face milling tests on AZ31 automotive magnesium alloy, providing insights into their suitability for high-demand industrial applications
Annealing-dependent elastic microstructure in a Zr-based metallic glass
No full textIn this letter, we demonstrate the robust presence of an elastic microstructure in a Zr-based metallic glass (MG) with a characteristic length-scale of the order of 100 nm. This length scale increases systematically towards the MG surface in differently sized casts, whereas thermal relaxation homogenizes both the internal length-scale gradient and the magnitude of the elastic fluctuations. Strongest changes during relaxation arise in the stiffest parts of the elastic microstructure. These findings indicate that the elastic microstructure emerges due to cooling constraints and may therefore be a microstructural manifestation of the internal residual stresses that arise during MG-solidification
Laser engineered architectures for magnetic flux manipulation on superconducting Nb thin films
No full textCustom shaped magnetic flux guiding channels have been fabricated on superconducting Nb thin films by laser nanopatterning of their surface. Preferential pathways are defined by suitable combination of imprinted anisotropic pinning domains through laser-induced periodic surface structures (LIPSS). Generated by the selective energy deposition of femtosecond UV laser pulses, quasi-parallel ripple structures are formed under optimized irradiation conditions. On average, each domain is formed by grooves with a lateral period of 260–270 nm and a depth about 80 nm. By combination of scanning and transmission electron microscopy, magneto-optical imaging, and conductive atomic force microscopy techniques, we conclude that the boundaries of the LIPSS-covered domains play a prominent role in the magnetic flux diversion process within the film. This is confirmed by dedicated modeling of the flux dynamics, combined with the inversion of the magneto-optical signal. The created metasurfaces enable control of the flux penetration process at the microscale
Secondary electron emission from gold microparticles in a transmission electron microscope: comparison of Monte Carlo simulations with experimental results
No full textWe measure the electron beam-induced current to analyze the electron-induced secondary electron (SE) emission from micron-sized gold particles illuminated by 80 and 300 keV electrons in a transmission electron microscope. A direct comparison of the experimental and simulated SE emission (SEE) employing Monte Carlo scattering simulations based on the GEANT4 toolkit yields overall good agreement with a noticeable discrepancy arising from the shortcoming of the GEANT4 scattering cross sections in the low-loss regime. Thus, the electron beam-induced current analysis allows to quantify the inelastic scattering including SEE in the transmission electron microscope and provides further insight into the charging mechanisms
Discovering synthesis targets: General discussion
No full textThis article is a discussion of the paper "Analysis of uncertainty of neural fingerprint-based models" by Christian W. Feldmann, Jochen Sieg and Miriam Mathea (Faraday discussions, 2025, DOI: 10.1039/D4FD00095A)