TY - GEN A1 - Daubitz, R. A1 - Schmidt, Dirk A1 - Schröder, Volkmar ED - Bothe, H. ED - Stolz, T. T1 - Ermittlung von Kenngrößen für die Druckentlastung von Gasexplosionen bei höheren Anfangsdrücken T2 - 165. PTB-Seminar ; 9. BAM/PTB-Kolloquium CY - Braunschweig, Deutschland DA - 2001-09-11 PY - 2001 SN - 3-89701-741-5 SN - 1434-2391 IS - 20 SP - 69 EP - 78 PB - Wirtschaftsverl. NW CY - Bremerhaven AN - OPUS4-1694 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Zuverlässigkeitsspezifische Gestaltung und Betriebsführung Trocknungstechnischer Anlagen am Beispiel der Kautschuktrocknung Überblick zum gegenwärtigen Stand der Untersuchungen T2 - 35. Sitzung des DECHEMA/GVC-Arbeitsausschusses CY - Frankfurt am Main, Deutschland DA - 1993-02-18 PY - 1993 AN - OPUS4-1701 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Sicherheitsbezogene Untersuchungen des Kautschuks zur Ableitung thermischer und /oder konzentrationsabhängiger Prozess- und Zustandsgrößen zur Indikation ablaufender sicherheitsrelevanter Phänomene PY - 1994 AN - OPUS4-1702 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk A1 - Schuster, H. A1 - Krause, Ulrich A1 - Winskowski, Jürgen T1 - Sicherheitstechnische Untersuchungen zur Gefährdungsbildung bei der Kautschuktrocknung T2 - 2. Fachtagung, Arbeits-, Anlagen- und Umweltsicherheit CY - Köthen DA - 1994-11-03 PY - 1994 AN - OPUS4-1703 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Numerische Simulation von Wasserstoffgas-Freisetzungen T2 - BAM-Kolloquium 1998 CY - Berlin, Deutschland DA - 1998-01-28 PY - 1998 AN - OPUS4-1704 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Numerische Simulation von Wasserstoffgasfreisetzungen T2 - Arbeitskreis Anlagensicherheit Berlin-Brandenburg CY - Berlin, Deutschland DA - 1998-09-25 PY - 1998 CY - Berlin AN - OPUS4-1705 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk A1 - Schalau, V. T1 - TRGS 300- Sicherheitstechnik, die kleine Sicherheitsanalyse T2 - Fortbildung gemäß § 9 der 5. BimSchV CY - --- DA - 2001-01-01 PY - 2001 AN - OPUS4-1706 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schuster, H. A1 - Schmidt, Dirk T1 - Zuverlässigkeitsspezifische Gestaltung und Betriebsführung eines Sicherheitssystems für trocknungstechnische Anlagen am Beispiel der Kautschukproduktion (Abschlussbericht, BMFT-FKZ 13RG9111) PY - 1995 AN - OPUS4-1707 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Dirk A1 - Krause, Ulrich A1 - Winskowski, Jürgen T1 - Bestimmung und Bedeutung sicherheitstechnischer Kenngrößen von Synthesekautschuk PY - 1995 SN - 0045-6519 SN - 0366-6301 VL - 47 IS - 6 SP - 316 EP - 321 PB - Fuchs - Informationsaufbereitung und -verbreitung CY - Leipzig AN - OPUS4-1708 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schuster, H. A1 - Schmidt, Dirk T1 - Sicherheitsforschung und Sicherheitstechnik - Jahresberichte 1993 und 1994 PY - 1995 VL - 1994 IS - 13RG9111 CY - Düsseldorf AN - OPUS4-1709 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Schmidt, Dirk T1 - Ein Beitrag zur Gestaltung eines Sicherheitssystems auf der Grundlage des Gefährdungsbildungsprozesses für verfahrenstechnische Anlagen, bezogen auf die Trocknung von Synthesekautschuk KW - chemische Verfahrenstechnik KW - Sicherheitstechnik KW - Synthesekautschuk KW - Trocknung PY - 1996 SP - 1 EP - 150 CY - Halle AN - OPUS4-1710 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Dirk T1 - Numerische Simulation von Wasserstoffausbreitungen PY - 1998 SN - 0341-1079 IS - 2 PB - Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-1711 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Dirk A1 - Krause, Ulrich A1 - Schmidtchen, Ulrich T1 - Numerical Simulation of Hydrogen Gas Releases Between Buildings PY - 1999 SN - 0360-3199 VL - 24 SP - 479 EP - 488 PB - Elsevier CY - Oxford AN - OPUS4-1712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thomsen-Schmidt, P. A1 - Hasche, K. A1 - Ulm, G. A1 - Herrmann, K. A1 - Krumrey, M. A1 - Ade, G. A1 - Stümpel, J. A1 - Procop, Mathias A1 - Beck, Uwe T1 - Realisation and metrological characterisation of thickness standards below 100 nm T2 - DVG Jahrestagung 2002 CY - Magdeburg, Germany DA - 2002-06-17 PY - 2002 SP - 1 EP - 9 PB - Deutsche Vakuum-Gesellschaft CY - Kaiserslautern AN - OPUS4-1936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt-Grund, R. A1 - Sturm, C. A1 - Hertwig, Andreas T1 - Ellipsometry and polarimetry - Classical measurement techniques with always new developments, concepts, and applications N2 - Ellipsometry is a matured experimental method, whose roots reach back into the early phase of modern optics itself. It is often attributed to be invented by Paul Drude in the last decade of the 19th century, but similar techniques had already been applied for years before Drude started his work. With this Special Issue about ellipsometry and related techniques, we hope to bring more attention to this method and advance and propagate it to be used by a broader community. We have collected a good mixture of articles: some texts are more in the line of users’ tutorial and best practice guides; others are intended to show recent developments of the method. With this collection, we also hope to show the generally rapidly expanding possibilities of ellipsometry and polarimetry to draw attention of new users and previously unrelated communities to this valuable tool. KW - Ellipsometry KW - Polarimetry KW - Surfaces KW - Thin films KW - Optical analysis PY - 2022 DO - https://doi.org/10.1515/aot-2022-0025 SN - 2192-8584 SN - 2192-8576 VL - 11 IS - 3-4 (Topical issue: Ellipsometry) SP - 57 EP - 58 PB - De Gruyter CY - Berlin AN - OPUS4-55467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schmidt, Alexandra A1 - Bresch, Harald A1 - Kämpf, K. A1 - Bachmann, V. A1 - Peters, T. A1 - Kuhlbusch, T. T1 - Development of a specific OECD Test Guideline on Particle Size and Particle Size Distribution of Nanomaterials N2 - In this research project, a new OECD Test Guideline (TG) for the determination of “Particle Size and Particle Size Distributions of Nanomaterials” was developed as the existing OECD TG 110 is considered to be outdated in terms of applicable size range (not covering sizes <200 nm) and methods. By its scope with an applicable size range from 1 to 1000 nm the new Test Guideline (TG PSD) covers the whole nanoscale. The TG PSD is applicable for particulate and fibrous nanomaterials. The prescribed, pairwise measurement of fibre diameter and length in the TG PSD allows for the first time to differen-tiate fibres with regard to their size-dependent hazard properties. Measurement instructions for each included method were validated within two separated interlaboratory comparisons, as a distinction between near spherical particles and fibres when applying the methods has to be made. Besides information on content and structure of the TG PSD, this final report outlines essential steps, considerations and organisational aspects during the development of the TG. Insights into the selec-tion, preparation and prevalidation of test materials used in the interlaboratory comparison are given. Finally, main results of the interlaboratory comparisons and their impacts on the TG PSD are pre-sented. N2 - Im Rahmen des Forschungsprojekts wurde eine neue OECD-Prüfrichtlinie (TG) für die Bestimmung von Partikelgrößen und Partikelgrößenverteilungen von Nanomaterialien entwickelt, da die existie-rende OECD TG 110 zur Bestimmung von Partikelgrößen in Bezug auf den anwendbaren Größenbe-reich und die gegebenen Methoden veraltet ist bzw. den Nanometerbereich < 200 nm nicht abdeckt. Mit ihrem Anwendungsbereich von 1 bis 1000 nm deckt die neue Prüfrichtlinie (TG PSD) die gesamte Nanoskala ab. Die TG PSD ist für partikel- und faserförmige Nanomaterialien anwendbar. Durch die, in der TG PSD vorgeschriebene, paarweise Messung von Faserdurchmesser und -länge ermöglicht diese TG zum ersten Mal Fasern hinsichtlich ihrer größenabhängigen Gefahrstoffeigenschaften zu unter-scheiden. Die Messanweisungen aller enthaltenen Methoden wurden im Rahmen von zwei getrennten Ringversuchen validiert, da bei der Anwendung der Methoden eine Unterscheidung zwischen Parti-keln und Fasern gemacht werden muss. Neben Angaben zum Inhalt und Struktur der TG PSD, befasst sich der vorliegende Abschlussbericht mit den wesentlichen Schritten, Überlegungen und organisatorischen Aspekten bei der Entwicklung der Prüfrichtlinie. Darüber hinaus werden Einblicke in die Auswahl, Vorbereitung und Prävalidierung der im Ringversuch verwendeten Testmaterialien gegeben. Schließlich werden die wichtigsten Ergeb-nisse aus den Ringversuchen und ihre Auswirkungen auf die TG PSD vorgestellt. KW - Nano KW - OECD KW - Particle size distribution KW - Testguideline KW - Nanoparticle PY - 2021 VL - 2021 SP - 1 EP - 47 PB - German Environment Agency CY - Dessau AN - OPUS4-54021 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bresch, Harald A1 - Schmidt, Alexandra A1 - Kämpf, K. A1 - Bachmann, V. A1 - Peters, T. A1 - Kuhlbusch, T. T1 - Draft OECD Test Guideline for the Testing of Chemicals - Particle Size and Particle Size Distribution of Nanomaterials N2 - Final Draft of the OECD Test Guideline for Particle Size and Particle Size Distribution of Nanomaterials. The OECD Working Party on Manufactured Nanomaterials (WPMN) has actively worked towards understanding possible safety issues for manufactured nanomaterials and has contributed significantly to resolving these by developing Test Guidelines, Guidance Documents, Test Reports and other publications with the aim of a safe use of manufactured nanomaterials. The OECD website (www.oecd.org/science/nanosafety) and the referenced publications contain more background information. Among others, the OECD Test Guideline “Particle Size Distribution/Fibre Length and Diameter Distributions” (TG 110, adopted in 1981) was identified to require an update to address the specific needs of manufactured nanomaterials as the TG 110 is currently only valid for particles and fibres with sizes above 250 nm. The WPMN prioritised to either update TG 110 to be applicable also to particles at the nanoscale or draft a new nanomaterial specific Test Guideline (TG). Eventually, it was decided to develop a new TG for particle size and particle size distribution measurements of nanomaterials covering the size range from 1 nm to 1000 nm for further justification. This TG overlaps with TG 110 in the size range from 250 nm to 1000 nm. When measuring particulate or fibrous materials, the appropriate TG should be selected depending on the size range of particles tested. In line with TG 110, the new TG for nanomaterials includes separate parts for particles and fibres. For the part of this TG which addresses particles, several methods applicable to nanomaterials were reviewed and included to take into account developments since 1981 when the TG110 was adopted. This TG includes the following methods: Atomic Force Microscopy (AFM), Centrifugal Liquid Sedimentation (CLS)/Analytical Ultracentrifugation (AUC), Dynamic Light Scattering (DLS), Differential Mobility Analysis System (DMAS), (Nano)Particle Tracking Analysis (PTA/NTA), Small Angle X-Ray Scattering (SAXS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). For measuring the diameter and length of fibres, analysing images captured with electron microscopy is currently the only method available. This TG includes Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). To test the validity of this TG, an ILC was performed. Test materials were chosen to reflect a broad 68 range of nanomaterial classes, e.g. metals, metal oxides, polymers and carbon materials. Where possible, well-characterised test materials were used. Additionally, the test materials were chosen, so that they reflect a broad range of sizes representing the size range 1 nm to 1000 nm and finally, for fibres only, aspect ratios from length/diameter of 3 to > 50. KW - Nano KW - OECD KW - Test guideline KW - Nanomaterial KW - Nanoparticle PY - 2021 UR - https://www.oecd.org/chemicalsafety/testing/draft-test-guideline-particle-size-distribution-nanomaterials.pdf SP - 1 PB - Organisation for Economic Co-operation and Development CY - Paris AN - OPUS4-53828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bresch, Harald A1 - Schmidt, Alexandra A1 - Kämpf, K. A1 - Bachmann, V. A1 - Peters, T. A1 - Kuhlbusch, T. T1 - Test Guideline No. 125 - Nanomaterial Particle Size and Size Distribution of Nanomaterials N2 - The OECD Working Party on Manufactured Nanomaterials (WPMN) has actively worked towards understanding possible safety issues for manufactured nanomaterials and has contributed significantly to resolving these by developing Test Guidelines, Guidance Documents, Test Reports and other publications with the aim of a safe use of manufactured nanomaterials. To address the specific needs of manufactured nanomaterials, the OECD Test Guideline No. 110 “Particle Size Distribution/Fibre Length and Diameter Distributions” was identified as one of the test guidelines (TGs) to require an update. The current TG 110 (adopted in 1981) is only valid for particles and fibres with sizes above 250 nm. The WPMN prioritised to either update TG 110 to be applicable also to particles at the nanoscale or draft a new nanomaterial specific (TG). Eventually, it was decided to develop a new TG that covers the size range from 1 nm to 1000 nm, intended for particle size and particle size distribution measurements of nanomaterials. Paragraph 11 provides further justification on the need for such measurements for nanomaterials. This TG overlaps with TG 110 in the size range from 250 nm to 1000 nm. When measuring particulate or fibrous materials, the appropriate TG should be selected depending on the size range of particles tested. In line with TG 110, the new TG for nanomaterials includes separate parts for particles and fibres. For the part of this TG which addresses particles, several methods applicable to nanomaterials were reviewed and included to take into account developments since 1981 when the TG 110 was adopted. This TG includes the following methods: Atomic Force Microscopy (AFM), Centrifugal Liquid Sedimentation (CLS)/Analytical Ultracentrifugation (AUC), Dynamic Light Scattering (DLS), Differential Mobility Analysis System (DMAS), (Nano)Particle Tracking Analysis (PTA/NTA), Small Angle X-Ray Scattering (SAXS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The method Single Particle Inductively Coupled Plasma Mass Spectrometry (sp-ICP-MS) could not be sufficiently validated within the interlaboratory comparison (ILC) carried out for the different methods in this TG (see also paragraph 6 for further details on the ILC). Applicability of sp-ICP-MS is strongly limited to nanomaterials with high mass values in combination with a sufficiently high particle size. However, the general method ICP-MS is widely used and the sp-mode for the size measurement of specific nanomaterials was successfully performed in ILCs elsewhere. The method is therefore included in the Appendix Part C of this TG, which further details the limitations of sp-ICP-MS. For measuring the diameter and length of fibres, analysing images captured with electron microscopy is currently the only method available. This TG includes Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). To test the validity of this TG, an ILC was performed. Test materials were chosen to reflect a broad range of nanomaterial classes, e.g. metals, metal oxides, polymers and carbon materials. Where possible, well-characterised test materials were used. Additionally, the test materials were chosen to reflect a broad range of sizes representing the size range 1 nm to 1000 nm. Specifically for fibres, a broad range of aspect ratios was included (length/diameter of 3 to > 50). Some of the test materials used are commercially available and further references are given in the validation report of the ILC. Sample preparation for physical chemical characterisation is critical for all listed methods. Due to the differences between individual nanomaterials and due to the wide range of individual material properties it is impossible to have a generic protocol to obtain the best possible sample preparation for every nanomaterial. Therefore, a generic protocol on sample preparation is not part of this TG. Information on sample preparation is given in the paragraphs 25-29, 33, 34 and 39 for particles and in paragraphs 159) for fibres. Further information on sample preparation of nanomaterials for physical chemical characterisation can be found in the OECD Guidance on Sample Preparation and Dosimetry for the Safety Testing of Manufactured Nanomaterials and elsewhere. KW - Nano KW - Nanomaterial KW - Nanoparticle KW - OECD KW - Test guideline PY - 2022 DO - https://doi.org/10.1787/20745753 SP - 1 EP - 72 PB - Organisation for Economic Co-operation and Development CY - Paris AN - OPUS4-55191 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schmidt, Jürgen T1 - Grafisch-rechnerisches Verfahren zum Erfassen der Zündhäufigkeit zündbarer Stoffe; Anwendung auf Datenmaterial aus dem Bereich der Statistik N2 - Die bisher bekannten und relativ unbefriedigenden Verfahren werden durch ein neues ergänzt, das auf der Basis des x' -Theorems arbeitet und über eine grafisch-rechnerische Linearisierung im DoppeI-Logarithmennetz Häufigkeitskurven enthält, die den Messpunkten optimal angepasst werden können. T3 - BAM Forschungsberichtreihe - 81 KW - Zündung KW - Zündmittel KW - Technische Zuverlässigkeit PY - 1981 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-3693 SN - 0938-5533 VL - 81 SP - 1 EP - 49 PB - Bundesanstalt für Materialprüfung (BAM) CY - Berlin AN - OPUS4-369 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schmidt, Peter A1 - Aurich, Dietmar A1 - Helms, Rolf A1 - Veith, Helmut A1 - Ziebs, Josef T1 - Untersuchungen über den Einfluß des Spannungszustandes auf bruchmechanische Kennwerte N2 - Zur Klärung der Problematik wurde eine Probe verwendet, bei der durch die geometrische Gestaltung trotz einachsiger Belastung parallel zur Rissfront eine zusätzliche Nennspannung wirksam wird. Ihnen werden Ergebnisse von Vergleichsproben ohne zusätzliche Nennspannung gegenübergestellt. Ergänzt worden die Untersuchungen durch Spannungsanalysen und vergleichende Rissaufweitungsmessungen. T3 - BAM Forschungsberichtreihe - 65 PY - 1980 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-3853 SN - 0938-5533 VL - 65 SP - 1 EP - 128 PB - Bundesanstalt für Materialprüfung (BAM) CY - Berlin AN - OPUS4-385 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - INPR A1 - Ganose, Alex A1 - Sahasrabuddhe, Hrushikesh A1 - Asta, Mark A1 - Beck, Kevin A1 - Biswas, Tathagata A1 - Bonkowski, Alexander A1 - Bustamante, Joana A1 - Chen, Xin A1 - Chiang, Yuan A1 - Chrzan, Daryl A1 - Clary, Jacob A1 - Cohen, Orion A1 - Ertural, Christina A1 - George, Janine A1 - Gallant, Max A1 - George, Janine A1 - Gerits, Sophie A1 - Goodall, Rhys A1 - Guha, Rishabh A1 - Hautier, Geoffroy A1 - Horton, Matthew A1 - Kaplan, Aaron A1 - Kingsbury, Ryan A1 - Kuner, Matthew A1 - Li, Bryant A1 - Linn, Xavier A1 - McDermott, Matthew A1 - Rohith Srinivaas Mohanakrishnan, A1 - Naik, Aakash A1 - Neaton, Jeffrey A1 - Persson, Kristin A1 - Petretto, Guido A1 - Purcell, Thomas A1 - Ricci, Francesco A1 - Rich, Benjamin A1 - Riebesell, Janosh A1 - Rignanese, Gian-Marco A1 - Rosen, Andrew A1 - Scheffler, Matthias A1 - Schmidt, Jonathan A1 - Shen, Jimmy-Xuan A1 - Sobolev, Andrei A1 - Sundararaman, Ravishankar A1 - Tezak, Cooper A1 - Trinquet, Victor A1 - Varley, Joel A1 - Vigil-Fowler, Derek A1 - Wang, Duo A1 - Waroquiers, David A1 - Wen, Mingjian A1 - Yang, Han A1 - Zheng, Hui A1 - Zheng, Jiongzhi A1 - Zhu, Zhuoying A1 - Jain, Anubhav T1 - Atomate2: Modular workflows for materials science N2 - High-throughput density functional theory (DFT) calculations have become a vital element of computational materials science, enabling materials screening, property database generation, and training of “universal” machine learning models. While several software frameworks have emerged to support these computational efforts, new developments such as machine learned force fields have increased demands for more flexible and programmable workflow solutions. This manuscript introduces atomate2, a comprehensive evolution of our original atomate framework, designed to address existing limitations in computational materials research infrastructure. Key features include the support for multiple electronic structure packages and interoperability between them, along with generalizable workflows that can be written in an abstract form irrespective of the DFT package or machine learning force field used within them. Our hope is that atomate2’s improved usability and extensibility can reduce technical barriers for high-throughput research workflows and facilitate the rapid adoption of emerging methods in computational material science. KW - Automation KW - DFT KW - Digitalisation KW - Materials design KW - Machine learning KW - Machine learned interatomic potentials PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624487 DO - https://doi.org/10.26434/chemrxiv-2025-tcr5h SN - 2573-2293 SP - 1 EP - 66 PB - American Chemical Society (ACS) CY - Washington, D.C. AN - OPUS4-62448 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abraham, O. A1 - Niederleithinger, Ernst A1 - Schmidt, F. A1 - Sörensen, J.D. A1 - Thöns, S. A1 - Chapeleau, X. A1 - Ferria, H. T1 - Infrastar Training School on Fatigue and Reliability Analysis of Structures - Training for Assessment of Risk N2 - The Infrastar training school provides lectures and hands-on training to Master and PhD students, early-stage researchers and (young) professionals on all aspects of asset management of civil infrastructures with respect to fatigue of materials. It is organized yearly since 2019 and up to 20 profiles are selected to attend the 3.5-day training. A team of 7 teachers provides insight in multi-disciplinary and intersectoral basic concepts in three core fields, ranging from the design to the dismantling of the structures (bridges and wind turbines): 1. Monitoring and auscultation, 2. Structural and action models, 3. Reliability, risk and decision analyses. Each year, a recognized expert is invited to deliver a keynote lecture to raise interest in a specific aspect of one of the fields covered. The presentation is recorded and published on the training school website. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Doctoral School KW - Multidisciplinary KW - Fatigue KW - Reliability PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563253 UR - https://www.ndt.net/article/ndtce2022/paper/61021_manuscript.pdf SP - 1 EP - 3 PB - NDT.net AN - OPUS4-56325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Jonathan T1 - Near-real-time in-situ powder bed anomaly detection using machine learning algorithms for high-resolution image analysis in PBF-LB/M N2 - In-situ captured visual images of the laser powder bed fusion process (PBF-LB/M) provide valuable insights into process dynamics. Automatic analysis of after-recoating images using machine learning algorithms enables the detection of process deviations to reduce scrap production. However, current industrial monitoring systems for PBF-LB/M are limited by low image resolution. While higher resolutions enable the system’s ability to capture smaller features, they increase storage and computational demand. Edge devices offer a solution by enabling near-real-time, on-premises image analysis within the machine and company network. In this study, high-resolution after-recoating images, captured with a spatial resolution of 17 µm/pixel and an image size of 9344 x 7000 pixels, were processed on an Nvidia Jetson Orin NX16 edge device. The images were downscaled, and anomaly detection algorithms were used to identify regions of interest for segmentation and classification at full resolution. To address computational constraints, state-of-the-art anomaly detection algorithms were evaluated and an appropriate downscaling factor for the on-edge implementation was determined. The EfficientAD algorithm achieved promising results, detecting anomalies within an inference time of less than 10 seconds. The presented framework enables anomaly detection with a maximum delay of one layer. This lays the foundation for the future development of near-real-time intervention in the PBF-LB/M process. T2 - ISAM 2025 – 6th International Symposium on Additive Manufacturing CY - Dresden, Germany DA - 21.05.2025 KW - Additive manufacturing KW - Image processing KW - In-situ monitoring KW - Powder bed fusion PY - 2025 AN - OPUS4-63231 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kaplan, F. A1 - Steinbock, O. A1 - Saloga, K. A1 - Ebell, Gino A1 - Schmidt, S. T1 - Überwachung der Brücke am Altstädter Bahnhof T1 - Monitoring of the bridge at the Altstadter Bahnhof in Brandenburg a. d. Havel N2 - Die B 1-Brücke am Altstädter Bahnhof war der wichtigste Verkehrsknotenpunkt in Brandenburg an der Havel. Im Dezember 2019 wurden die überführte Bundesstraße und die Straßenbahnlinie für den Verkehr gesperrt. Grund für die Sperrung war eine einsetzende Rissbildung in den Längsträgerstegen in Verbindung mit Hohlstellen, die letztlich auf gerissene Spanndrähte zurückgeführt werden. Um eine Sperrung der hoch frequentierten unterführten Verkehrswege zu verhindern, wurde ein umfangreiches Überwachungskonzept erforderlich. Wesentlicher Bestandteil dieses Konzepts war ein auf der Schallemissionsanalyse basierendes Monitoringsystem, mit dessen Hilfe Spanndrahtbrüche aufgezeichnet und lokalisiert werden konnten. Auf Grundlage der so gewonnenen Ergebnisse konnten Schwerpunkte für die Bauwerksprüfung abgeleitet werden. In diesem Bericht werden die gewonnenen Erkenntnisse zum messtechnisch erfassten Schadensfortschritt und den damit verbundenen visuell festgestellten Schäden beschrieben. Dabei werden die Besonderheit des verbauten konzentrierten Spannglieds (Spannblockverfahren nach TGL 173-33) und des Spannstahls in Bezug auf die Schadensbilder dargestellt. Die gewonnenen Erkenntnisse sollten bei der Beurteilung anderer Bauwerke mit vergleichbarer Bauart berücksichtigt werden. KW - Korrosion KW - Spannstahl KW - Spannungsrisskorrosion PY - 2022 DO - https://doi.org/10.1002/bate.202200008 SN - 0932-8351 VL - 99 IS - 3 SP - 222 EP - 230 PB - Ernst & Sohn AN - OPUS4-54485 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pallasch, Sebastian M. A1 - Bhosale, Manik A1 - Smales, Glen Jacob A1 - Schmidt, Caroline A1 - Riedel, Sibylle A1 - Zhao-Karger, Zhirong A1 - Esser, Birgit A1 - Dumele, Oliver T1 - Porous Azatruxene Covalent Organic Frameworks for Anion Insertion in Battery Cells N2 - Covalent organic frameworks (COFs) containing well-defined redox-active groups have become competitive materials for next-generation batteries. Although high potentials and rate performance can be expected, only a few examples of p-type COFs have been reported for charge storage to date with even fewer examples on the use of COFs in multivalent ion batteries. Herein, we report the synthesis of a p-type highly porous and crystalline azatruxene-based COF and its application as a positive electrode material in Li- and Mg-based batteries. When this material is used in Li-based half cells as a COF/carbon nanotube (CNT) electrode, a discharge potential of 3.9 V is obtained with discharge capacities of up to 70 mAh g−1 at a 2 C rate. In Mg batteries using a tetrakis(hexafluoroisopropyloxy)borate electrolyte, cycling proceeds with an averge discharge voltage of 2.9 V. Even at a fast current rate of 5 C, the capacity retention amounts to 84% over 1000 cycles. KW - COFs PY - 2024 DO - https://doi.org/10.1021/jacs.4c04044 VL - 146 IS - 25 SP - 17318 EP - 17324 PB - Journal of the American Chemical Society AN - OPUS4-60419 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stajanca, Pavol A1 - Chruscicki, Sebastian A1 - Homann, Tobias A1 - Seifert, Stefan A1 - Schmidt, Dirk A1 - Habib, Abdel Karim T1 - Detection of leak-induced pipeline vibrations using fiber-optic distributed acoustic sensing N2 - In the presented work, the potential of fiber-optic distributed acoustic sensing (DAS) for detection of small gas pipeline leaks (<1%) is investigated. Helical wrapping of the sensing fiber directly around the pipeline is used to increase the system sensitivity for detection of weak leak-induced vibrations. DAS measurements are supplemented with reference accelerometer data to facilitate analysis and interpretation of recorded vibration signals. The results reveal that a DAS system using direct fiber application approach is capable of detecting pipeline natural vibrations excited by the broadband noise generated by the leaking medium. In the performed experiment, pipeline vibration modes with acceleration magnitudes down to single ug were detected. Simple leak detection approach based on spectral integration of time-averaged DAS signals in frequency domain was proposed. Potential benefits and limitations of the presented monitoring Approach were discussed with respect to its practical applicability. We demonstrated that the approached is potentially capable of detection and localization of gas pipeline leaks with leak rates down to 0.1% of the pipeline flow volume and might be of interest for monitoring of short- and medium-length gas pipelines. KW - Distributed acoustic sensing KW - DAS KW - Distributed vibration sensing KW - DVS KW - Fiber-optic sensors KW - Pipeline monitoring KW - Leak detection KW - Pipeline vibrations PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-457953 UR - http://www.mdpi.com/1424-8220/18/9/2841 DO - https://doi.org/10.3390/s18092841 SN - 1424-8220 VL - 18 IS - 9 SP - 2841, 1 EP - 18 PB - MDPI AN - OPUS4-45795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Sebastian T1 - Charakterisierung eines technischen LAS-Produktes T2 - Tag der Chemie 2008 CY - Berlin, Germany DA - 2008-04-23 PY - 2008 AN - OPUS4-17492 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eichelbaum, M. A1 - Kneipp, Janina A1 - Schmidt, B.E. A1 - Panne, Ulrich A1 - Rademann, K. T1 - SERS and Multiphoton-Induced Luminescence of Gold Micro- and Nanostructures Fabricated by NIR Femtosecond-Laser Irradiation KW - Gold KW - Luminescence KW - Multiphoton fabrication KW - Sol-gel processes KW - Surface-enhanced Raman scattering PY - 2008 DO - https://doi.org/10.1002/cphc.200800417 SN - 1439-4235 SN - 1439-7641 VL - 9 IS - 15 SP - 2163 EP - 2167 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-18233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Sebastian T1 - Charakterisierung eines technischen LAS-Produktes T2 - ANAKON 2009 CY - Berlin, Germany DA - 2009-03-17 PY - 2009 AN - OPUS4-18725 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Jonathan T1 - Visual surface structure analysis of high-resolution images from visual in-situ process monitoring in laser powder bed fusion N2 - Parameter studies are a common step in selecting process parameters for powder bed fusion of metals with laser beam (PBF-LB/M). Density cubes manufactured with varied process parameters exhibit distinguishable surface structures visible to the human eye. Industrial visual in-situ monitoring systems for PBF-LB/M currently have limited resolution and are incapable of reliably capturing differences in the surface structures. For this work, a 65 MPixel high resolution monochrome camera is integrated in an industrial PBF-LB/M machine together with a high intensity led bar. Post-exposure images are taken to analyze differences in light reflection on the specimen’s surface. The grey level co-occurrence matrix is used to quantify the in-situ measured visual surface structure of nickel-based super alloy IN939 density cubes. The properties of the grey level co-occurrence matrix correlate to the energy input and resulting porosity of specimens. Low energy samples with lack of fusion flaws show an increased contrast in the grey level co-occurrence matrix compared to specimens with an optimal energy input. The potential of high-resolution images as reference data in in-situ process monitoring in PBF-LB/M is discussed. T2 - 77th IIW Annual Assembly and International Conference CY - Rhodos, Greece DA - 06.07.2024 KW - Additive manufacturing KW - Powder bed fusion KW - In-situ monitoring KW - Image processing KW - Lack of fusion PY - 2024 AN - OPUS4-60688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lüth, Peter A1 - Uhlig, S. A1 - Frost, K. A1 - Malow, Marcus A1 - Michael-Schulz, Heike A1 - Schmidt, Martin A1 - Zakel, Sabine T1 - CEQAT-DGHS interlaboratory tests for chemical safety: Validation of laboratory test methods by determining the measurement uncertainty and probability of incorrect classification including so-called “Shark profiles” N2 - Laboratory test results are of vital importance for correctly classifying and labelling chemicals as “hazardous” as defined in the UN Globally Harmonized System (GHS) / EC CLP Regulation or as “dangerous goods” as defined in the UN Recommendations on the Transport of Dangerous Goods. Interlaboratory tests play a decisive role in assessing the reliability of laboratory test results. Interlaboratory tests performed over the last 10 years have examined different laboratory test methods. After analysing the results of these interlaboratory tests, the following conclusions can be drawn: 1. There is a need for improvement and validation for all laboratory test methods examined. 2. To avoid any discrepancy concerning the classification and labelling of chemicals, the use of validated laboratory test methods should be state of the art, with the results accompanied by the measurement uncertainty and (if applicable) the probability of incorrect classification. This paper addresses the probability of correct/incorrect classification (for example, as dangerous goods) on the basis of the measurement deviation obtained from interlaboratory tests performed by the Centre for quality assurance for testing of dangerous goods and hazardous substances (CEQAT-DGHS) to validate laboratory test methods. This paper outlines typical results (e.g. so-called “Shark profiles” – the probability of incorrect classification as a function of the true value estimated from interlaboratory test data) as well as general conclusions and steps to be taken to guarantee that laboratory test results are fit for purpose and of high quality. T2 - 13th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions (ISHPMIE 2020) CY - Brunswick, Germany DA - 27.07.2020 KW - Dangerous goods KW - Hazardous substances KW - Interlaboratory test KW - Test method KW - Validation KW - Quality assurance KW - Measurement uncertainty KW - Incorrect classification KW - Shark profiles PY - 2021 DO - https://doi.org/10.1016/j.jlp.2021.104532 SN - 0950-4230/ VL - 72 SP - 104532 PB - Elsevier Ltd. AN - OPUS4-52751 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kast, Hermann A1 - Haid, August A1 - Goetze, A1 - Selle, Hermann A1 - Metz, Ludwig A1 - Koenen, Heinrich A1 - Schmidt, T1 - Eisenbahnverkehrsordnung - Prüfung und Gruppierung explosionsgefährlicher Gegenstände PY - 1929 SN - 0368-1785 VL - VI SP - 74 EP - 76 PB - Verl. Chemie CY - Berlin AN - OPUS4-42527 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Richard A1 - Grätz, Rainer A1 - Mair, Georg W. T1 - Die BAM als notifizierte Stelle - die Anerkennung europäischer Richtlinien mittels moderner QM-Werkzeuge T2 - BAM-Kolloquium CY - Berlin, Germany DA - 2002-05-15 PY - 2002 AN - OPUS4-6012 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schmidt, Jürgen T1 - Über eine Verteilungsfunktion mit Parametern für Median, Spannweite, Schiefe und Wölbung; Konzept und Anwendung N2 - Ein graphisch-rechnerisches Verfahren zur Beschreibung natürlicher Verteilungen. Besondere Merkmale zum Unterschied zu bekannten Verteilungsfunktionen sind dabei die Verwendung des Median anstelle des Erwartungswertes als Parameter, die mittlere Verteilungsdichten anstelle der Verteilungsdichte als Operationselement Lind die Möglichkeit der Extrapolation in die Ausläufer von Verteilungen. T3 - BAM Forschungsberichtreihe - 202 PY - 1994 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-2480 SN - 978-3-89429-481-7 SN - 0938-5533 VL - 202 SP - 1 EP - 52 PB - Wirtschaftsverlag NW CY - Bremerhaven AN - OPUS4-248 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Klamrowski, Günter A1 - Neustupny, Paul A1 - Deppe, Hans-Joachim A1 - Schmidt, Klaus A1 - Hundt, Jürgen T1 - Untersuchungen zur Dauerhaftigkeit von Faserzementen N2 - Unter Berücksichtigung des räumlichen Verformungsverhaltens von vollständig wassergesättigtem Material wurde eine Methode entwickelt, die als Beurteilungskriterium den Festigkeitsverlust infolge der Beanspruchung verwendet und das in der BAM für Holzwerkstoffe entwickelte Kurzzeitbewitterungsverfahren (XENOTEST 1200) auf Faserzemente anwendet, um zu klären, ob es für die Einschätzung des Langzeitverhaltens von Faserzement geeignet ist. T3 - BAM Forschungsberichtreihe - 156 PY - 1989 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-2943 SN - 978-3-88314-887-3 SN - 0938-5533 VL - 156 SP - 1 EP - 182 PB - Wirtschaftsverlag NW CY - Bremerhaven AN - OPUS4-294 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Deppe, Hans-Joachim A1 - Schmidt, Klaus T1 - Untersuchungen zur Beurteilung von Brettschichtverleimungen für den Holzleimbau N2 - Versuche mit Brettschichtverleimungen unterschiedlicher Qualitäten, Dauerstandsversuche im Wechselklima an besonderen Kreuzscherproben. Weiter wurden 19 handelsübliche PF- Leime untersucht. T3 - BAM Forschungsberichtreihe - 136 PY - 1987 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-3146 SN - 978-3-88314-636-6 SN - 0938-5533 VL - 136 SP - 1 EP - 66 PB - Wirtschaftsverlag NW CY - Bremerhaven AN - OPUS4-314 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schmidt, R. A1 - Klingenberg, G. A1 - Woydt, Mathias T1 - New lubrication concepts for environmental friendly machines N2 - The use of alternative oils for the lubrication of automobile engines has a potential of ecological and technical advantages. It requires the detailed knowledge of several thermophysical and viscometric properties in a large temperature range (mapping). Therefore, the following properties of up to twenty-eight different oils have been measured in the temperature range from 22 °C to 150 °C: density, heat capacity, thermal conductivity, viscosity at ambient pressure, viscosity under shear rates above 10 6 s-1, and the viscosity at elevated pressures (maximum 100 MPa). The last two have been measured with a substantially improved and a newly developed apparatus, respectively. The pressure- viscosity coefficient has been measured on four hydrocarbon-based, factory-fill oils, a paraffin oil and twenty-three alternative oils. Nine of the alternative oils are based partly or completely on esters, the other fourteen on polyglycols, two of them additionally on water. T3 - BAM Forschungsberichtreihe - 277 KW - Polyglycol KW - Ester KW - PAG KW - PPG KW - Factory fill KW - Hydrocarbon KW - Bio-no-tox oils KW - Engine oil KW - Bio-oils KW - EAL KW - Eco-lubricants KW - Heat capacity PY - 2006 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-1748 SN - 978-3-86509-528-3 SN - 0938-5533 VL - 277 SP - 1 EP - 59 PB - Wirtschaftsverlag NW CY - Bremerhaven AN - OPUS4-174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schannor, Mathias A1 - Oelze, Marcus A1 - Traub, Heike A1 - He, Yubei A1 - Schmidt, Robin A1 - Heidemann, Luisa A1 - Savic, Lynn Jeanette A1 - Vogl, Jochen A1 - Meermann, Björn T1 - Advancing Biomarker Research: In Situ Cu Isotope Analysis in Liver Tumors by LA-MC-ICP-MS N2 - Stable metal isotopes have received increasing attention as medical biomarkers due to their potential to detect changes in metal metabolism related to diseases. In particular, copper stable isotopes are a powerful tool to identify isotopic variation between tumors and healthy tissue, suggesting application in cancer diagnosis. However, potential mechanisms causing isotope fractionation, such as redox- or bond-forming reactions and interactions of metals during transmembrane import and export, are less well understood. Here, we established an in situ method using laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) to advance our understanding of the underlying processes responsible for isotope fractionation between normal and diseased tissues. Gelatin-based bracketing standards and quality control reference materials, crucial for laser ablation analysis, were developed to allow correction for instrumentally induced isotope fractionation during LA-MC-ICP-MS analysis. Using such matrix-matched standards, the method achieved intermediate precisions for delta values of better than 0.15 ‰ (2 s) for inorganic reference materials and of better than 0.17 ‰ (2 s) for biological reference materials. The developed routine was tested on rabbit VX2 liver tumor samples, a model system resembling human hepatocellular carcinoma (HCC) used to study liver cancer. In situ Cu isotope compositions between healthy (𝛿65/63NIST976(Cu) = −1.5 ‰ to 0.2 ‰) and tumorous (𝛿65/63NIST976(Cu) = 0.0 ‰ to 1.3 ‰) liver tissue show distinct differences in their isotope ratios. The observed isotopic dichotomy is consistent with previous solution-based MC-ICP-MS work, showing enrichment of heavy 65Cu in cancer biopsies relative to healthy tissue. KW - Biomarker KW - Laser Ablation KW - Reference Material PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626865 DO - https://doi.org/10.1021/acs.analchem.4c05626 SN - 1520-6882 VL - 97 IS - 8 SP - 4425 EP - 4432 PB - American Chemical Society (ACS) AN - OPUS4-62686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dirk, Schmidt A1 - Kreißig, Michael A1 - Gutte, Frank A1 - Th., Heidermann T1 - Ergebnisse beim Test von Flammendurchschlagsicherungen bei stabilen Detonationen bei atmosphärischen und nicht atmosphärischen Bedingungen N2 - Im Zuge der Umstellung auf grüne Energie, etwa bei der Nutzung von Wasserstoff und Ammoniak, gewinnen Flammendurchschlagsicherungen (FDS) weiter an Bedeutung für den Explosionsschutz. Flammendurchschlagsicherungen sind Armaturen, die in Rohrleitungen eingebaut werden, um das Fortschreiten von Explosionen und den Durchtritt von Flammen zwischen Anlagenteilen zu verhindern. Sie kommen vor allem in chemischen Anlagen, bei der Lagerung und dem Transport von Treibstoffen sowie an Tankstellen zum Einsatz und sind dort oft die einzige wirksame Maßnahme des konstruktiven Explosionsschutzes für brennbare Gase und Flüssigkeiten. Mit zunehmenden Betriebsdrücken und Temperaturen in modernen Industrieprozessen steigen die Anforderungen an FDS, die deshalb an die jeweiligen maximalen Betriebsbedingungen angepasst werden müssen. Im Rahmen eines Forschungsvorhabens wurden grundlegende Untersuchungen für ein neues Prüfverfahren durchgeführt, dass die veränderten Einsatzbedingungen der FDS einbezieht. KW - Flammendurchschlagsicherungen KW - Rohrleitungen KW - IIB3 und IIC Gasgemische KW - Detonationen KW - Nicht atmosphärische Bedingungen PY - 2025 SN - 2191-0073 VL - 15. IS - 07-08 SP - 25 EP - 30 PB - VDI Fachmedien GmbH und Co. KG CY - Düsseldorf AN - OPUS4-63989 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Jonathan T1 - High-resolution in-situ image analysis in laser powder bed fusion N2 - Visual images captured - in-situ - in laser powder bed fusion (PBF-LB/M) provide valuable insights into process dynamics. This poster presents methods for analyzing high-resolution images with a spatial resolution of 17 µm/pixel and a size of 9344 × 7000 pixels. In the context of identifying microstructural anomalies, the relationship between the contrast values derived from the grey-level co-occurrence matrix (GLCM) of post-exposure images and ex situ measurements of surface roughness, porosity, and melt pool depth is illustrated. Furthermore, a workflow to detect process anomalies in post recoating images using an edge device is presented. T2 - BAM Advisory Council Meeting CY - Berlin, Germany DA - 25.06.2025 KW - Additive manufacturing KW - High resolution camera KW - Image processing KW - In situ monitoring KW - Powder bed fusion PY - 2025 AN - OPUS4-63990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - BOOK A1 - Maiwald, Michael A1 - Bassler, M. A1 - Deilmann, M. A1 - Ens, W. A1 - Frenzel, F. A1 - Gerlach, M. A1 - Großmann, J. A1 - Grümbel, F. A1 - Heisterkamp, M. A1 - Kaiser, U. A1 - Lambrecht, A. A1 - Ohlenkamp, R. A1 - Pötter, T. A1 - Pyka, P. A1 - Roos, E. A1 - Schmidt, A. A1 - Schünemann, U. A1 - Theuer, M. A1 - Tukle, A. A1 - Weber, N. T1 - Technologie-Roadmap „Prozess-Sensoren 2027+“ N2 - Die Technologie-Roadmap „Prozess-Sensoren 2027+“ ist eine Weiterentwicklung vorgängiger Technologie-Roadmaps. Im Zentrum dieser Roadmaps stehen Sensoren zur Erfassung von physikalischen und chemischen Messgrößen mittels spezifischer und unspezifischer Messverfahren, die zur Steuerung und dem besseren Verständnis von Prozessen dienen. Die Roadmap fasst die gemeinsame Technologie- und Marktsicht von Anwendern, Herstellern und Forschungseinrichtungen im Bereich Prozess-Sensorik in der verfahrenstechnischen Industrie zusammen. Sie beschreibt die wesentlichen Trends im Bereich Prozess-Sensorik und künftige Handlungsbedarfe für Hersteller, Anwender sowie für Einrichtungen der Forschung und Lehre. Für die aktuellen und zukünftigen Anforderungen an Prozess-Sensoren werden 19 Thesen formuliert. Die Thesen basieren auf den Thesen der vorangegangenen Roadmaps, wobei die aus heutiger Sicht erforderlichen Anpassungen, Ergänzungen und teilweise auch Streichungen vorgenommen wurden. Die Thesen sind in 5 Themencluster eingeordnet. Digitalisierung und Nachhaltigkeit sind übergreifende Kernthemen der künftigen Entwicklung. KW - Technologie-Roadmap Prozess-Sensoren KW - Prozessindustrie KW - Prozessanalytik KW - Sensorik KW - Digitalisierung KW - NAMUR PY - 2021 SP - 1 EP - 63 AN - OPUS4-53741 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Becker, D. A1 - Konnertz, Nora A1 - Böhning, Martin A1 - Schmidt, J. A1 - Thomas, A. T1 - Light-switchable polymers of intrinsic microporosity N2 - The interest in (micro)porous systems is greater than ever before with microporous polymers finding application in areas such as gas storage/separation and catalysis. In contrast to the vast majority of publications on microporous polymers seeking ever higher values for surface area or uptake capacity for a particular gas, this work presents a means to render a microporous system responsive to electromagnetic stimuli. The incorporation of a diarylethene (DAE) derivative in the backbone of a polymer of intrinsic microporosity (PIM) produces a microporous system that exhibits photochromism as proven by UV–vis absorption and NMR studies. In the resulting DAE-PIM, surface area is not a fixed unalterable property but can be influenced by the external and nondestructive stimulus light in a reversible manner. Furthermore, in combination with Matrimid, free-standing membranes can be produced that display light-switchable diffusivity and permeability for carbon dioxide and oxygen. In this way, material scientists are offered the potential to employ only one system that can assume several states with different properties for each. KW - Gaspermeation KW - Diffusion KW - Polymer intrinsischer Mikroporosität KW - UV-VIS PY - 2016 DO - https://doi.org/10.1021/acs.chemmater.6b02619 SN - 0897-4756 VL - 28 IS - 23 SP - 8523 EP - 8529 PB - ACS CY - Whashington,DC AN - OPUS4-38735 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Ferrero, Fabio A1 - Malow, Marcus A1 - Schmidt, Martin A1 - Krause, Ulrich T1 - Leitfaden zur Brandvermeidung bei der Lagerung von Biomasse N2 - Die Menge an genutztem, verarbeitetem und gelagertem Holz steigt von Jahr zu Jahr. In der Folge konnte in den letzten fünf Jahren eine deutlich gestiegene Zahl von Bränden in Holzlagern und -halden festgestellt werden. Viele dieser Brände sind durch Selbstentzündung des Materials verursacht worden. Sind die Ursachen der Selbstentzündung bekannt, kann die Brandentstehung durch geeignete Maßnahmen vermieden werden. Die Fachgruppe II.2 „Reaktionsfähige Stoffe und Stoffsysteme“ der Bundesanstalt für Materialforschung und -prüfung hat in diesem Leitfaden das Thema aufgegriffen und die derzeit vorliegenden Erkenntnisse zusammenfassend dargestellt. Ziel des Leitfadens ist es, die Grundlagen der Selbstentzündung von Biomasse am Beispiel von Holz in übersichtlicher Form darzustellen und daraus praktische Hinweise zur Vermeidung der Selbstentzündung von Holzhalden abzuleiten, um so einen Weg für einen sicheren und nachhaltigen Umgang mit diesem Rohstoff zu ebnen. Dem Leitfaden liegen Ergebnisse des Forschungsvorhabens „Brandvermeidung bei der Lagerung von biogenen Brennstoffen“ zugrunde. Das Projekt wurde innerhalb der Fördermaßnahme „klimazwei – Forschung für den Klimaschutz und Schutz vor Klimawirkungen“ des Bundesministeriums für Bildung und Forschung finanziell gefördert (Förderkennzeichen 01LS05079). Für diese Förderung möchten die Autoren sich bedanken. T3 - BAM Forschungsberichtreihe - 284 PY - 2009 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-1678 SN - 978-3-9812354-1-8 SN - 0938-5533 VL - 284 SP - 1 EP - 22 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-167 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Merz, Benjamin A1 - Schmidt, Jonathan A1 - Poka, Konstantin A1 - Mohr, Gunther A1 - Polte, Julian A1 - Hilgenberg, Kai T1 - Impact of illumination technique on the detectability of irregularities in high-resolution images of visual in-situ process monitoring in Laser Powder Bed Fusion N2 - The layerwise geometry build-up of additive manufacturing (AM) enables the possibility of in-situ process monitoring. The objective is the detection of irregularities during the build cycle, ensuring component quality and process stability. Focus of this work is the visual in-situ monitoring of the process of powder bed fusion with laser beam of metals (PBF-LB/M). Current state of the art visual monitoring systems for PBF-LB/M are limited by low resolution, allowing the detection of gross flaws. In this work a 65 Mpixel high-resolution monochrome camera is integrated into a commercial PBF-LB/M machine enabling a spatial resolution of approx. 17.2 µm/Pixel. The observed inhomogeneities are clustered into directly detectable irregularities, and indirectly detectable irregularities that can be inferred from the surface. In parallel, two different illumination techniques are realized in the process chamber and compared. The impact of the distinct illumination technique, direct light and dark field, on the identification of irregularities is evaluated. KW - Powder bed fusion with laser beam of metals KW - In-situ monitoring KW - High-resolution camera KW - Illumination technique PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610929 DO - https://doi.org/10.1016/j.procir.2024.08.079 SN - 2212-8271 VL - 124 SP - 98 EP - 103 PB - Elsevier B.V. AN - OPUS4-61092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Einfluss von Rohrleitungsverzweigungen auf die Wirksamkeit von Deflagrationsrohrsicherungen N2 - Die Ergebnisse der experimentellen Untersuchungen zeigen einen deutlichen Einfluss der Rohrleitungsverzweigungen auf die ablaufenden Deflagrationen (Explosionsdruck und Flammenausbreitungsgeschwindigkeit) in der Rohrleitung. Eine erste numerische Simulation der beobachteten Abläufe in der Verzweigung, zeigt bereits eine rechte gute Übereinstimmung mit den experimentellen Daten. T2 - 14. Kolloquium zur chemischen und physikalischen Sicherheitstechnik (BAM-PTB-Kolloquium) CY - Berlin, Germany DA - 14.06.2016 KW - Deflagrationsrohrsicherungen KW - Verzweigte Rohrleitungen PY - 2016 AN - OPUS4-37175 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Habib, Abdel Karim A1 - Schalau, Bernd A1 - Schmidt, Dirk T1 - Simulation und experimentelle Untersuchungen der Schwergasausbreitung N2 - Aufgrund gestiegener Rechnerleistung finden heutzutage numerische Strömungssimulationen aus dem Bereich der CFD (Computational Fluid Dynamics) immer mehr Eingang in die Sicherheitstechnik. Bisherige Berechnungsverfahren zur Schwergasausbreitung basieren zum Teil auf empirischen Annahmen und sind in ihrem Anwendungsbereich eingeschränkt. Die zugrunde liegenden Formeln und Theorien erlauben außerdem meist nur eindimensionale Aussagen bezüglich der Konzentrationsverteilung in der Umgebung. Anhand von Literaturdaten und eigenen Freifeldversuchen zur Schwergasausbreitung soll die Leistungsfähigkeit von CFD-Berechnungen hinsichtlich ihres Kosten/Nutzen-Verhältnisses sowie im Vergleich zu herkömmlichen Modellen bewertet werden. Während die eigenen Freifeldversuche hauptsächlich zur Validierung der numerischen Simulationen dienen, können anhand der in der Literatur veröffentlichten Daten Vergleiche mit z. B. der VDI-Richtlinie 3783, Blatt 2 durchgeführt werden. KW - Schwergas KW - Ausbreitung KW - Simulation PY - 2013 SN - 0030-834X VL - 123 IS - 3 SP - 14 EP - 18 PB - Wirtschaftsverl. NW CY - Bremerhaven AN - OPUS4-29585 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habib, Abdel Karim A1 - Schalau, Bernd A1 - Schmidt, Dirk ED - Beyer, M. ED - Stolz, T. T1 - Simulation und experimentelle Untersuchungen der Schwergasausbreitung T2 - 13. BAM-PTB-Kolloquium zur chemischen und physikalischen Sicherheitstechnik CY - Braunschweig, Germany DA - 2013-06-18 KW - Schwergas KW - Ausbreitung KW - Simulation PY - 2013 SN - 978-3-95606-062-5 SN - 1868-5838 SP - 1 EP - 7 AN - OPUS4-29584 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Habib, Abdel Karim A1 - Bonow, G. A1 - Kroll, A. A1 - Hegenberg, J. A1 - Schmidt, L. A1 - Barz, T. A1 - Schulz, D. T1 - Forschungsprojekt RoboGasInspector: Gaslecksuche mit autonomen mobilen Robotern N2 - Im Rahmen des Förderprogramms AUTONOMIK des Bundesministeriums für Wirtschaft und Technologie wurde in einem Konsortium aus neun Projektpartnern der Prototyp eines autonomen mobilen Roboters zur Gaslecksuche in ausgedehnten Industrieanlagen entwickelt. Anhand verschiedenartiger Sensorik zur Selbstlokalisation und Navigation wurde die autonome Beweglichkeit des Systems für beliebige Anlagen realisiert, mit der Option anhand von Teleoperation manuell in den Prozess einzugreifen. Ausgestattet mit Video- und Gasfernmesstechnik ist der Roboter imstande, Inspektionsaufgaben in Industrieanlagen durchzuführen, ohne in mögliche Gefahrenbereiche direkt einfahren zu müssen und ohne, dass ein Mensch vor Ort anwesend ist. Der Roboter kann zur routinemäßigen Inspektion von Anlagen oder zur gezielten Untersuchung spezifischer Anlagenteile eingesetzt werden. Dank der verwendeten Fernmesstechnik können auch Anlagenteile inspiziert werden, die aufgrund ihrer beschränkten Zugänglichkeit mittels herkömmlicher Messtechnik nur schwer zu inspizieren sind. KW - Lecksuche KW - Roboter KW - Gasausbreitung KW - Simulation PY - 2013 SN - 2191-0073 VL - 3 IS - 5 SP - 10 EP - 15 PB - Springer-VDI-Verl. CY - Düsseldorf AN - OPUS4-29586 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habib, Abdel Karim A1 - Schalau, Bernd A1 - Schmidt, Dirk ED - Pierucci, S. ED - Klemes, J.J. ED - De Rademaeker, E. ED - Fabiano, B. ED - Buratti, S.S. T1 - Comparing different methods for calculating the gas dispersion N2 - When handling flammable and/or toxic liquids or gases, the gas dispersion following a release of substance is a scenario to be considered in the risk assessment to determine the lower flammability distance (LFD) and toxicity thresholds. In this work a comparison of different gas dispersion tools of varying complexity ranging from a simple Gaussian model over a boundary layer model (BLM) and a Lagrangian model to CFD (in this case ANSYS CFX v14) is presented. The BLM covers the special case of liquid releases with formation of a pool. It does not only solve the gas dispersion but also calculates the evaporating mass flow out of the pool. The simulation values are compared to each other and to experimental data resulting mainly from our own open air experiments covering the near field and carried out on the Test Site Technical Safety of BAM (BAM-TTS) for different release types (pool evaporation, gas release) and topologies. Other validation data were taken from literature and cover large scale experiments in the range of several 100 m. T2 - 14th International symposium on loss prevention and safety promotion in the process industries CY - Florence, Italy DA - 12.05.2013 KW - Gas dispersion KW - Simulation PY - 2013 SN - 978-88-95608-22-8 SN - 1974-9791 N1 - Serientitel: Chemical engineering transactions – Series title: Chemical engineering transactions IS - 31 SP - 1 EP - 6 PB - AIDIC, Associazione Italiana di Ingegneria Chimica CY - Milano AN - OPUS4-29587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Habib, Abdel Karim A1 - Schalau, Bernd A1 - Schmidt, Dirk T1 - Comparing tools of varying complexity for calculating the gas dispersion N2 - When handling flammable and/or toxic liquids or gases, the gas dispersion following a release of substance is a scenario to be considered in the risk assessment to determine the lower flammability distance (LFD) and toxicity thresholds. In this work a comparison of different gas dispersion tools of varying complexity ranging from a simple Gaussian model over a boundary layer model (BLM) and a Lagrangian model to CFD (in this case ANSYS CFX v14) is presented. The BLM covers the special case of liquid releases with formation of a pool. It does not only solve the gas dispersion but also calculates the evaporating mass flow out of the pool. The simulation values are compared to each other and to experimental data resulting mainly from our own open air experiments covering the near field and carried out on the Test Site Technical Safety of BAM (BAM-TTS) for different release types (pool evaporation, gas release) and topologies. Other validation data were taken from literature and cover large scale experiments in the range of several 100 m. KW - Gas dispersion KW - Modeling KW - CFD KW - Hazard assessment KW - Gauss KW - Lagrange PY - 2014 DO - https://doi.org/10.1016/j.psep.2014.02.014 SN - 0957-5820 SN - 1744-3598 SP - 1 EP - 6(?) PB - Elsevier CY - Amsterdam AN - OPUS4-30529 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Methoden zur Quantifizierung von Risiken verfahrenstechnischer Anlagen T2 - ProcessNet-Arbeitsausschuss "Risikomanagement" CY - Frankfurt am Main, Germany DA - 2007-03-20 PY - 2007 AN - OPUS4-14604 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schmidt, Dirk A1 - Schalau, Bernd A1 - Acikalin, Hatice Aydan A1 - Habib, Abdel Karim T1 - Vergleich von Methoden zur Quantifizierung von Risiken verfahrenstechnischer Anlagen T2 - 8. Fachtagung "Anlagen-, Arbeits- und Umweltsicherheit" CY - Köthen, Deutschland DA - 2006-11-09 KW - Risiko KW - QRA KW - Purple Book KW - ARAMIS KW - LOPA KW - Fehlerbaum KW - Gefährdungsermittlung KW - Auswirkungsbetrachtungen KW - Häufigkeiten KW - Datenbank PY - 2006 SN - 3-936415-48-X SP - 1 EP - 14(?) PB - VDI, Hallescher Bezirksverein CY - Halle AN - OPUS4-12745 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Vergleich von Methoden zur Quantifizierung von Risiken verfahrenstechnischer Anlagen T2 - 8. Fachtagung Anlagen-, Arbeits- und Umweltsicherheit CY - Köthen, Germany DA - 2006-11-09 PY - 2006 AN - OPUS4-13749 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Möglichkeiten zur Qualifizierung von Risiken verfahrenstechnischeer Anlagen T2 - Erfahrungsaustausch für amtlich anerkannte Sachverständige der Anlagenüberwachung der Industrie CY - Königswinter, Germany DA - 2007-03-20 PY - 2007 AN - OPUS4-14611 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Jonathan A1 - Merz, Benjamin A1 - Poka, Konstantin A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Surface structure analysis using visual high-resolution in situ process monitoring in laser powder bed fusion N2 - Parameter studies are a common step in selecting process parameters for laser powder bed fusion of metals (PBF-LB/M). Density cubes are commonly used for this purpose. Density cubes manufactured with varied process parameters can exhibit distinguishable surface structures visible to the human eye. The layer-wise process enables such surface structures to be detected during manufacturing. However, industrial visual in situ monitoring systems for PBF-LB/M currently have limited resolution and are incapable of reliably capturing small differences in the surface structures. In this work, a 65 MPixel high-resolution monochrome camera was integrated into an industrial PBF-LB/M machine together with a high-intensity LED (light-emitting diode) bar. Post-exposure images were taken to analyse differences in light reflection of fused areas. It is revealed that the grey-level co-occurrence matrix can be used to quantify the visual surface structure of nickel-based superalloy Inconel®939 density cubes per layer. The properties of the grey-level co-occurrence matrix correlate to the energy input and the resulting porosity of density cubes. Low-energy samples containing lack of fusion flaws show an increased contrast in the grey-level co-occurrence matrix compared to specimens with optimal energy input. The potential of high-resolution images for quality assurance via in situ process monitoring in PBF-LB/M is further discussed. KW - Additive manufacturing KW - Powder bed fusion KW - In situ monitoring KW - Image processing KW - High resolution camera PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626685 DO - https://doi.org/10.1007/s40194-025-01955-1 SN - 1878-6669 SP - 1 EP - 15 PB - Springer Science and Business Media LLC AN - OPUS4-62668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Dutschke, Andreas A1 - Lohrer, Christian A1 - Seeger, Stefan A1 - Kurth, Lutz A1 - Schmidt, Martin A1 - Kaiser, Michael A1 - Stattaus, Kim A1 - Panne, Ulrich T1 - Determination of reaction products during a large firework display in Germany T2 - 11th International symposium on fireworks CY - Puerto Vallarta, México DA - 2009-04-20 KW - Firework display KW - Reaction products KW - Particles KW - Sound pressure PY - 2009 SN - 978-0-9734123-8-3 SP - 50 EP - 63 AN - OPUS4-19383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schalau, Bernd A1 - Schmidt, Dirk T1 - Kritische Bewertung der Einflussfaktoren einer QRA am Beispiel einer Flüssiggaslageranlage T2 - Arbeitskreis Sicherheitsmanagement Berlin Brandenburg CY - Berlin, Germany DA - 2006-05-19 PY - 2006 AN - OPUS4-12364 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sprachmann, J. A1 - Wachsmuth, T. A1 - Bhosale, M. A1 - Burmeister, D. A1 - Smales, Glen Jacob A1 - Schmidt, M. A1 - Kochovski, Z. A1 - Grabicki, N. A1 - Wessling, R. A1 - List-Kratochvil, E. J. W. A1 - Esser, B. A1 - Dumele, O. T1 - Antiaromatic Covalent Organic Frameworks Based on Dibenzopentalenes N2 - Despite their inherent instability, 4n π systems have recently received significant attention due to their unique optical and electronic properties. In dibenzopentalene (DBP), benzanellation stabilizes the highly antiaromatic pentalene core, without compromising its amphoteric redox behavior or small HOMO−LUMO energy gap. However, incorporating such molecules in organic devices as discrete small molecules or amorphous polymers can limit the performance (e.g., due to solubility in the battery electrolyte solution or low internal surface area). Covalent organic frameworks (COFs), on the contrary, are highly ordered, porous, and crystalline materials that can provide a platform to align molecules with specific properties in a well-defined, ordered environment. We synthesized the first antiaromatic framework materials and obtained a series of three highly crystalline and porous COFs based on DBP. Potential applications of such antiaromatic bulk materials were explored: COF films show a conductivity of 4 × 10−8 S cm−1 upon doping and exhibit photoconductivity upon irradiation with visible light. Application as positive electrode materials in Li-organic batteries demonstrates a significant enhancement of performance when the antiaromaticity of the DBP unit in the COF is exploited in its redox activity with a discharge capacity of 26 mA h g−1 at a potential of 3.9 V vs. Li/Li+ . This work showcases antiaromaticity as a new design principle for functional framework materials. KW - SAXS KW - MOUSE KW - Covalent Organic Frameworks KW - Batteries PY - 2023 DO - https://doi.org/10.1021/jacs.2c10501 SP - 1 EP - 12 PB - ACS Publications AN - OPUS4-56958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Ramírez, A. A1 - Crasselt, C. A1 - Schmidt, W. A1 - Resch-Genger, Ute T1 - Utilizing optical spectroscopy and 2',7'-difluorofluorescein to characterize the early stages of cement hydration N2 - The increasingly sophisticated nature of modern, more environmentally friendly cementitious binders requires a better understanding and control particularly of the complex, dynamic processes involved in the early phase of cement hydration. In-situ monitoring of properties of a constantly changing system over a defined period of time calls for simple, sensitive, fast, and preferably also non-invasive methods like optical spectroscopy KW - Flourescence KW - Optical probe KW - Sensor KW - Dye KW - Flourescin KW - Photophysics KW - PH KW - Quantum yield KW - Quality assurance KW - Mechanism KW - Cement KW - Concrete KW - Building material KW - Hydration KW - Process monitoring PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-537176 DO - https://doi.org/10.1088/2050-6120/ac2da0 SN - 2050-6120 VL - 10 IS - 1 SP - 2 EP - 13 PB - IOP Science AN - OPUS4-53717 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rödiger, S. A1 - Liebsch, C. A1 - Schmidt, C. A1 - Lehmann, W. A1 - Resch-Genger, Ute A1 - Schedler, U. A1 - Schierack, P. T1 - Nucleic acid detection based on the use of microbeads: a review N2 - Microbead-based technologies represent elegant and versatile approaches for highly parallelized quantitative multiparameter assays. They also form the basis of various techniques for detection and quantification of nucleic acids and proteins. Nucleic acid-based methods include hybridization assays, solid-phase PCR, sequencing, and trapping assays. Microbead assays have been improved in the past decades and are now important tools in routine and point-of-care diagnostics as well as in life science. Its advances include low costs, low workload, high speed and high-throughput automation. The potential of microbead-based assays therefore is apparent, and commercial applications can be found in the detection and discrimination of single nucleotide polymorphism, of pathogens, and in trapping assays. This review provides an overview on microbead-based platforms for biosensing with a main focus on nucleic acid detection (including amplification strategies and on selected probe systems using fluorescent labeling). Specific sections cover chemical properties of microbeads, the coupling of targets onto solid surfaces, microbead probe systems (mainly oligonucleotide probes), microbead detection schemes (with subsections on suspension arrays, microfluidic devices, and immobilized microbeads), quantification of nucleic acids, PCR in solution and the detection of amplicons, and methods for solid-phase amplification. We discuss selected trends such as microbead-coupled amplification, heterogeneous and homogenous DNA hybridization assays, real-time assays, melting curve analysis, and digital microbead assays. We finally discuss the relevance and trends of the methods in terms of high-level multiplexed analysis and their potential in diagnosis and personalized medicine. Contains 211 references. KW - Microbead KW - Microbead array KW - PCR KW - Microfluidic KW - Real-time KW - Multiplex PY - 2014 DO - https://doi.org/10.1007/s00604-014-1243-4 SN - 0026-3672 SN - 1436-5073 VL - 181 IS - 11-12 SP - 1151 EP - 1168 PB - Springer CY - Wien AN - OPUS4-31183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ramirez, Alejandra A1 - Pauli, Jutta A1 - Crasselt, C. A1 - Simon, S. A1 - Schmidt, W. A1 - Resch-Genger, Ute T1 - The effect of a polycarboxylate ether on C3A / CaSO4.2H2O passivation monitored by optical spectroscopy N2 - Polycarboxylate ethers (PCEs) are widely used in construction, but the exact nature of their interaction with cement is still debated. Aiming at a better understanding of the role of tricalcium Aluminate (C3A) in cement hydration, we assessed the potential of optical spectroscopy in combination with a water-soluble fluorescent organic reporter dye (S0586) to monitor the early hydration of C3A in the presence of 26 wt% CaSO4.2H2O (C3A26G-S) with and without PCE. As optical methods, steady-state fluorescence and diffuse reflectance (UV–VisDR) spectroscopy were employed. Phase characterization and particle size distribution were performed with in-situ X-ray diffraction (in-situ XRD) and dynamic light scattering (DLS). Our results show that fluorescence and UV–VisDR spectroscopy can be used to monitor the formation of metastable phases by the disaggregation of the dye S0586 in a cement paste as well as changes in ettringite formation. Addition of PCE slowed down the disaggregation of the dye as reflected by the corresponding changes of the dyes absorption and fluorescence. This prolonged induction period is a well-known side effect of PCEs and agrees with previous reported calorimetric studies and the Inhibition of gypsum dissolution observed by in-situ XRD. This demonstrates that fluorescence and UV–VisDR spectroscopy together with a suitable optical probe can provide deeper insights into the influence of PCE on C3A-gypsum hydration which could be e.g., utilized as screening method for comparing the influences of different types of PCEs. KW - Fluorescence KW - Cement KW - Nano KW - Particle KW - Optical spectroscopy KW - PCE KW - XRD KW - Calorimetry KW - Monitoring KW - Diffuse KW - Reflection KW - Phase KW - Dye KW - Optical probe KW - Cyanine KW - Sensor KW - Method KW - Analysis PY - 2020 DO - https://doi.org/10.1016/j.conbuildmat.2020.121856 VL - 270 SP - 121856 PB - Elsevier Ltd. AN - OPUS4-52118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Y. A1 - Ulbricht, Alexander A1 - Schmidt, F. A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Schwitalla, A.D. T1 - Micro-CT analysis and mechanical properties of low dimensional CFR-PEEK specimens additively manufactured by material extrusion N2 - Material extrusion of thermoplastic polymers enables the realization of complex specific designs with high performance composites. The present study aims at evaluating the mechanical properties of carbon fiberreinforced semi-crystalline thermoplastic polymer polyether ether ketone (CFR-PEEK) manufactured by material extrusion and correlating them with results obtained by micro-CT. Samples in the shape of small bars were provided by Kumovis (Munich, Germany). The determination of surface roughness and density was followed by three-point bending tests. To reveal the pore distribution as well as the fusion quality of CFR PEEK when applied with external forces, micro-CT scans were performed with an X-ray microscope before and after the mechanical test to localize the sites where the fracture is generated. The density of CFR-PEEK bars indicated that they had superior mechanical properties compared with our previous study on unfilled 3D printed PEEK (bending modulus: (5.4 ± 0.5) GPa vs. (1.05 ± 0.05) GPa to (1.48 ± 0.10) GPa; bending strength: (167 ± 11) MPa vs. (51 ± 15) to (193 ± 7) MPa). Micro-CT analyses revealed the local 3D-distribution of voids. Voids of 30 μm diameter are nearly spherical and make up the main part of the total porosity. The larger the voids, the more they deviate from a spherical shape. Significant lack-of-fusion voids are located between the deposited filaments. By growing and merging, they act as seeds for the forming fracture line in the region of the flexural specimens where the maximum local tensile stresses occurred under bending load. Our work provides a detailed analysis of printed PEEK with fiber additive and relates this with mechanical properties. KW - CFR-PEEK KW - Material extrusion (MEX) KW - FFF KW - Surface topography KW - Bending property KW - Micro-CT PY - 2023 DO - https://doi.org/10.1016/j.jmbbm.2023.106085 SN - 1751-6161 VL - 146 SP - 1 EP - 9 PB - Elsevier Ltd. AN - OPUS4-58112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Lück, S. A1 - Schmidt, V. A1 - Grothausmann, R. A1 - Hilger, A. A1 - Manke, I. T1 - Missing wedge computed tomography by iterative algorithm DIRECTT N2 - A strategy to mitigate typical reconstruction artefacts in missing wedge computed tomography is presented. These artefacts appear as elongations of reconstructed details along the mean direction (i.e. the symmetry centre of the projections). Although absent in standard computed tomography applications, they are most prominent in advanced electron tomography and also in special topics of X-ray and Neutron tomography under restricted geometric boundary conditions. We investigate the Performance of the DIRECTT (Direct Iterative Reconstruction of Computed Tomography Trajectories) algorithm to reduce the directional artefacts in standard procedures. In order to be sensitive to the anisotropic nature of missing wedge artefacts, we investigate isotropic substructures of metal foam as well as circular disc models. Comparison is drawn to filtered backprojection and algebraic techniques. Reference is made to reconstructions of complete data sets. For the purpose of assessing the reconstruction Quality, Fourier transforms are employed to visualize the missing wedge directly. Deficient reconstructions of disc models are evaluated by a length-weighted boundary orientations. The DIRECTT results are assessd at different signal-to-noise ratios by means of local and integral evaluation Parameters. KW - Tomography KW - Algorithm KW - Reconstruction KW - Computed tomography KW - Electron tomography KW - Image morphology KW - Iterative reconstruction KW - Missing wedge PY - 2016 DO - https://doi.org/10.1111/jmi.12313 SN - 1365-2818 VL - 261 IS - 1 SP - 36 EP - 45 PB - Wiley CY - Hoboken, New Jersey, USA AN - OPUS4-35801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rauchegger, Christian A1 - Schröder, Volkmar A1 - Lohse, Volkmar A1 - Schmidt, Dirk A1 - Thévenin, D. T1 - Release and dispersion of heavy gases - experimental results and numerical simulations N2 - Heavy gases in large quantities are used worldwide in various industries. Past incidents, such as the liquefied gas disaster in Viareggio (2009) have shown that these materials are difficult to handle in a safe manner. According to the German Hazardous Incident Ordinance (StörfallVO 2000 - 12. BImSchV) plant operators with 'extended responsibilities' must produce a report in which they verify that, in the event of an unintentional gas release, the surrounding area will not be aversely affected. The essential elements of this report include calculations of both releasedmass flow and gas dispersion. Using models such as the VDI guideline 3783 (state of the art in Germany) plant operators are able to predict the characteristics of likely gas dispersions. Within the framework of the reported experimental trials, the release process of heavy gases from standard gas cylinders was investigated. Using the results of this investigation a calculation methodology has been developed which is able to predict the mass flow of a gas-phase release. As input parameters only the geometry of the gas cylinder, the material properties of the respective fluid as well as the environmental parameters such as velocity of approach and air temperature are required. In the course of modeling various approaches for nucleate boiling have been tested for their applicability. Both the calculation methodology and a comparison between the calculated and experimental results will be presented. Within the same framework of experimental trials, the dispersion process of the aforementioned heavy gases was also investigated. The dispersed gas cloud in this case was considered as originating from a continuous point source under ambient conditions. For the various Trials concentrations both in the heavy gas (≥ 1 vol.-%) and in the neutral gas field (≤ 3000 ppm) were measured. In the immediate area of the release the length, width and height of the heavy gas cloud were evaluated. The experimental results, comparison calculations and the measurement techniques will be presented. T2 - 8th Global congress on process safety (GCPS) CY - Houston, TX, USA DA - 01.04.2012 KW - Heavy gases KW - Gas releases KW - Gas Dispersion KW - VDI Guideline 3783 PY - 2012 UR - https://www.researchgate.net/publication/267345315_Release_and_Dispersion_of_Heavy_Gases_-_Experimental_Results_and_Numerical_Simulations SN - 978-0-8169-1071-7 IS - Paper 104aq SP - 1 EP - 16 AN - OPUS4-25772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raute, Julius A1 - Schmidt, Jonathan A1 - Jokisch, Torsten A1 - Biegler, Max A1 - Rethmeier, Michael T1 - Prozessführung und erreichbare Nahtqualitäten: Elektronenstrahlschweißen von additiv gefertigtem Inconel 939 N2 - Additive Fertigungstechnologien wie das Laser-Pulverbett-Verfahren bieten großes Potenzial für die Fertigung von Neu und Ersatzteilen für stationäre Gasturbinen aus Nickelsuperlegierungen wie Inconel 939 (IN939). Um die Integration in bestehende Baugruppen zu ermöglichen und Bauraumbeschränkungen zu überwinden, muss die Prozesskette der additiven Fertigung um geeignete Fügetechniken erweitert werden. Die vorliegende Arbeit beschäftigt sich daher mit dem Schweißen von Inconel 939. Hierbei werden Bleche aus Gussmaterial und der additiven Herstellung mittels Laser im Pulverbett beim Elektronenstrahlschweißen verglichen. Im Fokus der Untersuchung stehen die erreichbare Nahtqualität im Hinblick auf geometrische Unregelmäßigkeiten sowie innere Defekte in Form von Mikrorissen in der Wärmeeinflusszone. Bei der Auswertung der geschweißten Proben zeigen sich keine Unterschiede in der Ausbildung der Nahtform zwischen dem additiv gefertigten Material und dem Gusswerkstoff. Für beide Materialien ließ sich bei hohen Vorschubgeschwindigkeiten von 20 mm/s die höchste Bewertungsgruppe für Strahlgeschweißte Nähte nach DIN EN ISO 13919-1 erreichen. Unabhängig von der Herstellungsart zeigen beide Materialien eine Zunahme der Rissneigung mit steigendem Vorschub. Das Material aus der additiven Herstellung weist aufgrund seiner Mikrostruktur insgesamt jedoch deutlich weniger Mikrorisse auf, was Potenzial für die Anwendung in der Praxis eröffnet. KW - Elektronenstrahlschweißen KW - PBF-LB/M KW - Inconell939 PY - 2025 UR - https://www.schweissenundschneiden.de/artikel/prozessfuehrung-und-erreichbare-naht-qualitaeten-elektronenstrahlschweissen-von-additiv-gefertigtem-inconel-939 DO - https://doi.org/10.53192/SUS202510 VL - 77 IS - 10 SP - 2 EP - 8 PB - DVS Media Verlag CY - Eltville am Rhein, Deutschland AN - OPUS4-64300 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas A1 - Hilger, A. A1 - Manke, I. A1 - Lück, S. A1 - Schmidt, V. A1 - Grothausmann, R. T1 - Reduzierung von Missing-Wedge-Artefakten der CT mit DIRECTT N2 - Typische 'Missing Wedge'(MW)-Artefakte in Rekonstruktionen der Computertomografie können mit dem iterativen DIRECTT-Algorithmus (Direkte iterative Rekonstruktion computertomografischer Trajektorien) unterdrückt werden. Die durch fehlende Projektionswinkel bedingten MW-Restriktionen betreffen bisher nur Sonderapplikationen der Röntgen- und Neutronentomografie, müssen in der Nanometer auflösenden Elektronentomografie jedoch als Standard akzeptiert werden. Die MW-Artefakte werden besonders effektiv mit einer spezifischen DIRECTT-Prozedur partiell diskreter Zwischenlösungen beseitigt. Für die Beurteilung der Abbildungsqualität werden Rekonstruktionen von vollständigen und unvollständigen Mess- und Modell-Datensätzen erzeugt und mit Ergebnissen anderer Algorithmen (gefilterte Rückprojektion (FBP) und ART-Methoden) verglichen. Die Fourier-Transformierten der Rekonstruktionen demonstrieren die erfolgreiche Ergänzung der fehlenden Information im MW-Bereich. Die quantitative Bewertung der lokalen Rekonstruktionsqualität mit Methoden der räumlichen Statistik ergibt auch für unterschiedliche Signal-Rausch-Verhältnisse signifikante Vorteile gegenüber FBP und ART. KW - Computertomographie (CT) KW - Rekonstruktionsalgorithmus KW - DIRECTT KW - Missing wedge KW - Statistische Bewertung KW - Elektronentomographie KW - Iterative Rekonstruktion PY - 2014 UR - http://www.hanser-elibrary.com/doi/pdf/10.3139/120.110612 SN - 0025-5300 VL - 56 IS - 9 SP - 716 EP - 721 PB - Hanser CY - München AN - OPUS4-31377 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tötzke, C. A1 - Manke, I. A1 - Gaiselmann, G. A1 - Bohner, J. A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Hentschel, Manfred P. A1 - Schmidt, V. A1 - Banhart, J. A1 - Lehnert, W. T1 - A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers N2 - We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell. KW - PEM fuel cell KW - Gas diffusion layer (GDL) KW - Compression device KW - X-ray tomography KW - Synchrotron KW - Tortuosity PY - 2015 DO - https://doi.org/10.1063/1.4918291 SN - 0034-6748 SN - 1089-7623 VL - 86 IS - 4 SP - 043702-1 EP - 043702-6 PB - American Institute of Physics CY - Melville, NY, USA AN - OPUS4-33081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Jonathan T1 - High resolution visual in-situ process monitoring in SONRISA N2 - The LuFo Project "SONRISA" presented an update on its objectives for the coming years to Working Group 3 – In-Situ Process Monitoring – during the EASA/FAA Additive Manufacturing Workshop 2025. As part of this update, BAM provided a brief overview of its prior work in high-resolution visual in-situ process monitoring for PBF-LB/M, which will be integrated into the project. The presentation included a comparison between the BAM system and the OEM in-situ monitoring system “EOSTATE PowderBed” and an outline of the correlation between texture contrast and the occurrence of lack-of-fusion anomalies in high resolution after exposure images.g. T2 - EASA–FAA AM Workshop 2025 CY - Cologne, Germany DA - 21.10.2025 KW - Additive manufacturing KW - High resolution camera KW - Lack of fusion PY - 2025 AN - OPUS4-64456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, R. T1 - SEM or TEM for the characterization of nanoparticles? N2 - Scanning Electron Microscopy (SEM) or Transmission Electron Microscopy (TEM) ? This is a question, nowadays discussed in EM labs of research and industry involved in the characterization and metrology of nanoparticles. The Scanning principle is adapted to TEM, the Transmission mode is adapted to Ultra High Resolution SEM. Can modern SEM replace TEM, reach atomic resolution even without Cs corrector or nm lateral resolution for X-ray Spectroscopy (EDX)? Due to the development of a New Cold Field Emission (NCFE) electron source Hitachi SEMs SU9000 and SU8200 can deliver routinely sub-nm image resolution and EDX mappings at very high count rates and a lateral EDX resolution of a few nm. A TiO2 sample provided by BAM was analysed at 30 kV using low kV STEM – simultaneously with the Through-the-lens (TTL) SE detector, the Bright Field transmission and Dark Field transmission signals. By this method a pixel-precise information of the particle’s surface using SE, its chemical nature using DF-STEM and its crystalline structure using Bright Field signal is given in one 40sec scan. The advantage of this observation mode compared to Ultra Low Voltage imaging is outlined. T2 - 7. NRW Nano-Konferenz CY - Münster, Germany DA - 07.12.2016 KW - SEM KW - TEM KW - Nanoparticles PY - 2016 AN - OPUS4-38936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Wang, K. ED - Shah, S.P. ED - Khayat, K. T1 - Casting process improvement by optimization of mixture composition and high range water reducing agent modification N2 - Since its invention in the early 1990’s, self-consolidating concrete has never become well established in the ready-mix sectors worldwide. The reason for this can be mainly found in the fact that the sophisticated compositions are sensitive against changing environments. This lack of robustness can be attributed to the interaction between cement hydration reaction and high range water reducing agent (HRWRA). Understanding the relevant mechanisms that control the initial flow performance as well as the flow retention helps optimizing SCC mixtures that perform either steadily in one specific environment or that perform largely similarly at steadily changing environments. This paper depicts how HRWRAs interact with clinker and hydration phases and discusses the important role of the charge density of a polycarboxylic HRWRA in the way the rheology is affected. Based on rheometric results and observations of the Vicat setting times, it is shown that increasing charge densities of the HRWRA and decreasing water to powder ratios (w/p) reduce the flow retention and have lesser retarding effect on the setting. Based on the discussion, optimization procedures for the mixture composition and the HRWRA modification are suggested to achieve optimized performance for varying environmental situations or highest robustness for specific conditions. T2 - SCC 2013 - 5th North American conference on the design and use of self-consolidating concrete CY - Chicago, IL, USA DA - 12.05.2013 KW - Polycarboxylate KW - Cement hydration KW - Adsorption KW - Mixture composition KW - Environmental conditions PY - 2013 SP - 1 EP - 10 AN - OPUS4-28581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Becker, S. A1 - Lu, Z. A1 - Leinitz, Sarah A1 - Schmidt, Wolfram A1 - Stephan, D. A1 - von Klitzing, R. ED - Mechtcherine, V. ED - Khayat, K. ED - Secrieru, E. T1 - Particle Interactions in Silica Systems in Presence of Superplasticizer N2 - The flowability of cement paste is of great importance in today’s construction industry and is influenced by additives such as superplasticizers (SP). One type of SPs are polycarboxylate ether type SPs. These additives electrostatically bind with the negatively charged carboxylic groups at the backbone to the positively charged clinker phases. To model positively charged clinker phases with adsorbed SP, silicon Wafers are pre-coated with cationic polyethylenimine (PEI) and SP is adsorbed onto the coated surface (Si/PEI/SP). Two different polycarboxylate ether type (PCE) SP are compared – one for ready-mix concrete and one for precast concrete. In this preliminary study the interaction forces between Si/PEI/SP surface and a silica microsphere (colloidal probe) are investigated under mild physico-chemical conditions (pH *6, ion concentration <10−5 M) using Colloidal Probe Atomic Force Microscopy (CP-AFM). The interaction force between the model surfaces is attractive for low concentration of SP. The force changes from attractive to repulsive by increasing amount of SP. The force upon approach reveals a biexponential behavior. The exponential decay at large and short surface separations are attributed to electrostatic and steric interactions, respectively. The steric forces of the SP for ready-mix concrete show a steeper onset than the SP for precast concrete. The quantification of these interaction forces will be compared to rheological measurements of similar systems. Furthermore, the parameters will be changed to better approach the conditions in real systems, i.e. higher pH and ionic strength. This helps to understand how the forces on the nanoscale influence the macroscopic rheology. KW - Interfacial forces KW - Silica beads KW - Superplasticizer KW - AFM PY - 2019 SN - 978-3-030-22565-0 DO - https://doi.org/10.1007/978-3-030-22566-7 SN - 2211-0844 VL - 23 SP - 571 EP - 579 PB - Springer ET - 1 AN - OPUS4-49183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Barthel, Maria A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Betontechnologische Ansätze zur Vermeidung innerstädtischer Hitzeinseln N2 - Die Versiegelung von Oberflächen, Bebauung und die Ausweitung städtischer Gebiete führen weltweit besonders in sonnenreichen Regionen zu innerstädtischen Hitzeinseln. Diese Flächen wirken als Wärmespeicher, so dass an Sonnentagen eine Temperaturdifferenz bis zu 10 K zwischen Stadt und umliegendem Land entstehen kann. Verstärkt wird dieser sogenannte Urban Heat Island Effect (UHIE) durch die meist direkte Abführung des anfallenden Regenwassers in die Kanalisation, wodurch eine Kühlung durch stetige Verdunstung unterbunden ist, Mit steigender Urbanisierung wächst auch die Bedeutung dieses Phänomens. Innerstädtische Hitzeinseln ziehen direkte wirtschaftliche und soziale Folgen nach sich, da hohe Temperaturen eine teure Klimatisierung der Städte bedingen. So entsteht ein erhöhter Verbrauch an Ressourcen sowie zusätzliche Abwärme. Das Wohlbefinden und die Gesundheit der Bevölkerung verschlechtern sich bei sehr hohen Temperaturen, was zu sinkender Leistungsfähigkeit und sogar zu einer erhöhten Sterberate führen kann. T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 12.09.2012 PY - 2012 SN - 978-3-00-034075-8 VL - 2 IS - 3.07 SP - 2-0042 EP - 2-0050 AN - OPUS4-26545 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Potentials for savings in the production of self-compacting and high strength concrete for precast concrete elements N2 - Over the course of the last decades, concrete construction has significantly changed from mass application towards sophisticated more innovative, future oriented, and performance based materials technology. Today concrete no longer consists of cement, water, and aggregates, but can be enhanced significantly by using supplementary additions and chemical admixtures. Advancements in admixtures eventually facilitated the development of new concrete types such as self-compacting concrete (SCC) and high performance concrete (HPC) by uncoupling the workability from the water-cement ratio (w/c). While for traditional concrete types the major mixture parameter for the workability and strength were the w/c and the grading of the aggregates, for SCC and HPC the performance parameters are more complicated and the performance depends highly on the powder components. This makes the system more sophisticated and in parallel more prone to scatter during the production. The complexity and difficulty to predict the effects of changes in the process and mixture makes it very difficult to identify the right potentials for savings. T2 - ICCX Central Europe CY - Ossa, Poland DA - 11.02.2016 KW - Rheology KW - Self-compacting concrete KW - High strength concrete KW - Packing density KW - Superplasticizers PY - 2016 SP - 18 EP - 20 AN - OPUS4-36883 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Einfluss der Verarbeitungstemperatur auf die Eigenschaften von SVB bei Verwendung von Fließmittel und weiteren Zusatzmitteln N2 - Nachdem vor ca. 20 Jahren in Japan die Entwicklung der selbstverdichtenden Betone begann, dauerte es weitere 10 Jahre, bis diese Entwicklung auch Europa erreichte. Obwohl im Fertigteilsektor bereits deutlich mehr SVB zum Einsatz kommt als im Transportbetonbereich, bleiben die Produktionsmengen hinter dem zurück, was die Potenziale und Chancen dieser Technologie eigentlich erwarten ließen. Eine Ursache für die geringe Marktverbreitung sind die stark schwankenden und teilweise nur schwer beherrschbaren Frischbetoneigenschaften dieser Betone. KW - SVB KW - SCC KW - Zusatzmittel KW - Rheologie KW - Fließmittel Betontechnologie KW - Frischbetoneigenschaften PY - 2007 SN - 0373-4331 IS - 12 SP - 40 EP - 49 PB - Bauverl. BV CY - Gütersloh AN - OPUS4-16444 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Vasilic, Ksenija A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Stark, J. T1 - Experimental and numerical studies on calibration of a rotational rheometer for cementitious materials T2 - 17. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 2009-09-23 PY - 2009 SN - 978-3-00-027265-3 VL - 1 SP - 1-1135 - 1-1140 CY - Weimar AN - OPUS4-20300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Ramge, Peter A1 - Kühne, Hans-Carsten T1 - Efecto de las condiciones de almacenamiento del cemento en las propiedades de procesamiento y endurecimiento del hormigón / As consequências das condicoes de armazenamento do cimento nas qualidades do processamento e endurecimento do concreto PY - 2009 SN - 0373-4331 SN - 1865-6528 N1 - Sprachen: Spanisch/Portugiesisch - Languages: Spanish/Portuguese VL - 3 SP - 2 EP - 9 PB - Bauverl. CY - Gütersloh AN - OPUS4-20239 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Challenges of the African Environmental Conditions for Concrete Mixture Compostion T2 - Workshop "Cement and Concrete for Africa", BAM CY - Berlin, Germany DA - 2011-08-17 PY - 2011 AN - OPUS4-24726 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Alexander, Mark A1 - John, Vanderley T1 - Education for sustainable use of cement based materials N2 - Structural design and application have always been linked to the compressive strength of concrete as the main relevant criterion. This was justifiable in the past, where concrete consisted of water, ordinary Portland cement and aggregates, but this concept is no longer relevant for modern and more sustainable cement and concrete. Despite these new developments, existing standards, guidelines and academic curricula have not been much updated and are still used worldwide. There is a need to change this situation by proper education of the users. This overview describes the challenges that arise at a user Level from the higher complexity of modern concrete, and defines needs and requirements for enhanced applicability of sustainable concrete concepts. Furthermore, recommendations are given on how better concrete practice can be communicated to all the involved parties, from civil and design engineers to constructors and site-appliers on the construction site. KW - Cement KW - Concrete KW - Sustainability KW - Environment KW - Carbon footprint KW - Education KW - Climate PY - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0008884616307189?via%3Dihub DO - https://doi.org/10.1016/j.cemconres.2017.08.009 SN - 0008-8846 SN - 1873-3948 VL - 114 SP - 103 EP - 114 PB - Elsevier AN - OPUS4-47673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kühne, Hans-Carsten A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Uzoegbo, H. C. T1 - Building practice and concrete infrastructure development in eastern and southern Africa N2 - The construction sector has traditionally been a source of employment in African regions. However, due to policy changes, cut backs in public investments as well as a fall in the number of employments in the private sector have been observed in many countries. Furthermore a shift from registered companies to informal contractors could be noticed. Many contractors offer services they do not provide permanently or for which the required equipment has to be borrowed. A study that was published in 2000 about the situation in Tanzania pointed out that only ca. 15% of the enterprises that offer concrete works own a concrete mixer. The building practice with concrete varies widely over the African continent. Whereas the level of technology and the infrastructure for cement and concrete in South Africa is elaborate, in East Africa and particularly those that were heavily suffering from civil war during the nineties of the last century, the availability of cement and concrete is poor and these materials are far from being everyday building practice. Most of the population relies on indigenous forms of construction requiring wood obtained from felling of forest trees and ultimately contributing to de-forestation. Informal settlements in South-Africa and Kenya are literal evidence where originally green natural vegetation has been turned into artificial desert-like landscapes. PY - 2011 SN - 1437-9023 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 3 SP - 32 EP - 37 PB - ad-media-Verl. CY - Köln AN - OPUS4-25360 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - EN 206:2014: Cusum method or mean value criterion? / EN 206:2014: Kusum-Verfahren oder Mittelwertkriterium? N2 - Für die Anforderungen an Beton für Gebäude und higenieurbauwerke gilt seil Juli 2014 die EN 206:2.014 anstelle der EN 206-1:2000. In diesem Zusammenhang werden .sogenannte Kontrollkarten für den Konfonnltätsniiehweis zugclassen. Die EN 2.06:2.014 bezeichnet die Verwendung ilcs Mittelwertkritcriuins als Methode B und die Verwen düng von Kontrollkarten als Methode C. Kontrollkarten auf Basis von kumulativen Summen (Kiisum) sind sehr effektive Methoden zur Produktionsstcuerung. Die Anwendung wird In BS 5703-2:2001 geregelt. In England. Südafrika und Australien sind Kusum-Kontrollkartensystcme int Alltag der Betonherstcller etabliert, allerdings dient deren Anwendung nicht dem konkreten Konfbrmitätsnachweis, sondern der Abstimmung einer stabilen und zugleich wirtschafllichcn Produktion. Eine Einführung von Kusum-basierten Kontrollkarten für die Konformitätsbewertung wirft insofern die berechtigte Frage auf, ob das Nachweissystem gleichwertig mit dem bewährten Mittelwertkriterium ist. Im vorliegenden Artikel sollen zunächst kurz die Funktionsweise und die Vorteile von Kusum-Kontrollkarien dargcstclll werden, bevor eine vergleichende Bewertung von Kusum-Mcthode und Mittclwcrtkriterium dun hgelührl wird. KW - EN 206:2014 KW - Cusum method KW - Mean value criterion PY - 2014 SN - 0373-4331 SN - 1865-6528 N1 - Sprachen: Deutsch/Englisch - Languages: German/English VL - 80 IS - 12 SP - 24 EP - 31 PB - Bauverl. CY - Gütersloh AN - OPUS4-33576 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Paul, S.C. A1 - Pirskawetz, Stephan A1 - Van Zijl, G.P.A.G. A1 - Schmidt, Wolfram T1 - Acoustic emission for characterising the crack propagation in strain-hardening cement-based composites (SHCC) N2 - This paper presents the analysis of crack propagation in strain-hardening cement-based composite (SHCC) under tensile and flexural load by using acoustic emission (AE). AE is a non-destructive technique to monitor the development of structural damage due to external forces. The main objective of this research was to characterise the cracking behaviour in SHCC in direct tensile and flexural tests by using AE. A better understanding of the development of microcracks in SHCC will lead to a better understanding of pseudo strain-hardening behaviour of SHCC and its general performance. ARAMIS optical deformation analysis was also used in direct tensile tests to observe crack propagation in SHCC materials. For the direct tensile tests, SHCC specimens were prepared with polyvinyl alcohol (PVA) fibre with three different volume percentages (1%, 1.85% and 2.5%). For the flexural test beam specimens, only a fibre dosage of 1.85% was applied. It was found that the application of AE in SHCC can be a good option to analyse the crack growth in the specimens under increasing load, the location of the cracks and most importantly the identification of matrix cracking and fibre rupture or slippage. KW - Acoustic emission KW - Crack Detection (B) KW - Microcracking (B) KW - Fibre Reinforcement (E) KW - Tensile Properties (C) PY - 2015 DO - https://doi.org/10.1016/j.cemconres.2014.12.003 SN - 0008-8846 SN - 1873-3948 VL - 69 SP - 19 EP - 24 PB - Pergamon Press CY - New York, NY AN - OPUS4-33579 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Mota, Berta A1 - Ramirez Caro, Alejandra T1 - Einfluss der gesteinskörnung auf die Rheologie von Beton N2 - Die meisten Einflüsse auf die Rheologie von Beton wirken auf sehr kleinen Skalenebenen. Einflussgrößen im Millimeter oder Zentimeterbereich sind im Wesentlichen auf den Sand und die Gesteinskörnung beschränkt. Letztere machen aber in den meisten Betonen 50 %-70 % des Gesamtvolumens aus, was bei Untersuchungen zur Steuerung der Verarbeitungseigenschaften von Beton häufig vernachlässigt wird. Während Betonzusatzmittel und Zusatzstoffe bei geeigneter Wahl die Rheologie sehr gezielt beeinflussen können, eignen sich Sand und Gesteinskörnung weniger gut zur Steuerung der Rheologie, aber sie tragen zur Rheologie des Gesamtsystems bei. Hierbei können Effekte aus Sand und Gesteinskörnung die Effekte von Zusatzmitteln und Zusatzstoffen überlagern und im ungünstigsten Falle sogar nahezu unwirksam machen. Deshalb sollten Ergebnisse zur Verarbeitbarkeit von Bindemittelsystemen nur mit großer Sorgfalt auf Beton übertragen werden. Es ist wichtig, den Einfluss des Sandes und der Gesteinskörnung besser zu verstehen, um diese so abzustimmen, dass sie Effekte aus Fließmitteln positiv ergänzen anstatt diesen entgegenzuwirken. Durch eine gezielte Abstimmung lassen sich Kosten wirksam sparen. KW - Gesteinskörnung KW - Rheologie KW - Fließgrenze KW - Viskosität KW - Beton PY - 2018 VL - 3 SP - 42 EP - 51 PB - ad-media GmbH CY - Köln AN - OPUS4-47044 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Leinitz, Sarah A1 - Kühne, Hans-Carsten ED - Ludwig, H.-M. T1 - Einfluss der Partikelvolumenfraktion auf die Rheologie und die Effektivität von Polysaccharid-Stabilisierern in Gegenwart von Polycarboxylatether-Fließmitteln N2 - Zur Untersuchung der Wirkungsweise von ST ohne und in Gegenwart von FM wurden Untersuchungen an Zementleimen mit unterschiedlichen Φρ und variierten St-Modifikationen durchgeführt. Folgendes kann zusammengefasst werden: Mit zunehmendem Φρ nimmt der Einfluss aller beobachteten ST auf To und Πpl gegenüber dem wässrigen System ab. Bei hohem Φρ reduzieren alle ST Πpl. Diutan Gum und die hochmodifizierte Stärke können aber ein erhöhtes -r0 bewirken. In Gegenwart von FM werden ST insbesondere bei höheren FM-Dosierungen wirksam mit Bezug auf erhöhtes Πpl. Erhöhtes t0 erzielten nur ST-DG und ST-npg. Setzfließmaßversuche konnten darüber hinaus zeigen, dass Stärken besonders effektiv wirken, wenn der Feststoffgehalt sehr hoch ist, während Diutan Gum eine höhere Wirksamkeit aufweist, wenn höhere Wassergehalte im System sind. Die Wirkungsweise von ST ist sehr stark von p und der Gegenwart von FM abhängig. Die Ergebnisse zeigen. dass für Stärken die Modifikation eine sehr große Rolle spielen kann und dass weitere Untersuchungen zeigen müssen, inwieweit ST auf bestimmte Anwendungen maßgeschneidert werden können. T2 - 19. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 16.09.2015 KW - Fließmittel KW - Stabilisierer KW - Polycarboxylatether KW - Polysaccharide KW - Rheologie PY - 2015 SN - 978-3-00-050225-5 VL - 1 SP - 1-1263 EP - 1-1270 AN - OPUS4-34869 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - The African-European SPIN Network - Linking Experts to Foster Innovation in Cement and Concrete T2 - Workshop Cement and Concrete Technology at the University of the Witwaterand CY - Johannesburg, South Africa DA - 2012-09-07 PY - 2012 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-26728 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Grünewald, S. A1 - Ferrara, L. A1 - Dehn, F. T1 - Design of concrete for high flowability: progress report of fib task group 4.3 N2 - Flowable concretes can differ significantly from traditional vibrated concrete. Concrete types like self-compacting concrete (SCC), ultra high performance concrete (UHPC) and high performance fibre reinforced cementitious composites (HPFRCCs) require novel mix design approaches. This has consequences for the production and the performance in the hardened state. Mix designs for flowable concretes can incorporate a wide variety of innovative admixtures or components: e.g. superplasticisers increase the flowability and allow for significant reduction of the water content, shrinkage compensating admixtures or superabsorbent polymers support sound and damage free curing processes, viscosity modifying admixtures enhance the robustness, and new fibre types allow for sophisticated and tailored structural performance. The new Model Code has limitations regarding the application of flowable concrete, e.g. thresholds for the minimum aggregate size and the maximum strength. Provisions are added to include fibres for structural design. fib Task Group 4.3 aims at facilitating the use of innovative flowable materials for designing concrete structures and considers three aspects of flowable concrete: material properties, production effects and structural boundary conditions and performance. This paper reports about the progress of fib TG 4.3 related to the mix design of flowable concrete and discusses the present state-of-the-art concerning admixtures and robustness. T2 - fib Symposium (Proceedings) - Concrete - Innovation and design CY - Copenhagen, Denmark DA - 18.05.2015 KW - Admixtures KW - Fib model code KW - Fibres KW - Flowable concrete KW - Mix design KW - Robustness PY - 2015 SP - 1 EP - 10 AN - OPUS4-33800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram T1 - Wirkungsweise verschiedener Fließmittel N2 - In den vergangenen Jahrzehnten hat sich die Betonbauweise beträchtlich von einer Massenanwendung hin zu einer innovativeren, zukunfts- und leistungsorientierten Werkstofftechnologie weiterentwickelt. Heutzutage besteht Beton nicht mehr länger nur aus Zement, Wasser und Gesteinskörnungen, sondern kann unter Anwendung von Zusatzstoffen und chemischen Zusatzmitteln erheblich verbessert werden. Gleichzeitig beschränken die Betonspezifikationen sich nicht mehr auf den Elastizitätsmodul und Druckfestigkeit, sondern Beton kann ebenfalls zur Erfüllung zahlreicher Anwendungskriterien wie Dauerhaftigkeit, Verarbeitbarkeit, Ästhetik, Brandverhalten und vieler anderer mehr beitragen. Gleichzeitig ist jedoch die Zusammensetzung von Beton wegen der Vielzahl an interagierenden Mischungskomponenten komplizierter geworden. Das Verständnis der Auswirkungen der veränderten Mischungskomponenten ist eine Herausforderung, aber auch der Schlüssel zu einer innovativen Betontechnologie. PY - 2015 SN - 1439-7706 VL - 3 SP - 2 EP - 6 PB - ad-media-Verl. CY - Köln AN - OPUS4-33727 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram T1 - Mode of action of different superplasticisers N2 - Over the course of the last decades, concrete construction has significantly changed from mass application towards sophisticated more innovative, future oriented, and performance based materials technology. Today concrete no longer consists of cement, water, and aggregates, but can be enhanced significantly by using supplementary additions and chemical admixtures. At the same time the concrete specifications are no longer limited to Young’s modulus and compressive strength, but concrete may need to be designed for a multiple of application criteria such as durability, workability, optics, fire behaviour, and many more. However at the same time, the composition of concrete has become more complex due to the higher number of mutually interacting mixture constituents. Understanding the effects of changed mixture constituents is challenging but a good understanding is the key to innovative concrete technology. PY - 2015 SN - 1437-9023 IS - 3 SP - 2 EP - 6 PB - ad-media-Verl. CY - Köln AN - OPUS4-33581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram ED - Amziane, Sofiane ED - Sonebi, M. ED - Charlet, K. T1 - Mode of operation of polysaccharide stabilising agent in cement based systems and interactions with superplasticisers N2 - Polysaccharides are incorporated into cement based systems in order to modify the rheological properties. Typically cellulose ethers, sphingan gums or starch ethers are applied. Depending upon their chemistry, molecular architecture, and adsorption tendency, polysaccharides interact differently with the entire cementitious system. Some stabilising agents like diutan gum mainly affect the cementitious paste; other stabilising agents like starch tend to interact with the sand fraction and even with the coarse aggregates. Cellulose shows more divers performances. Often stabilising admixtures like polysaccharides are used, when sophisticated rheological properties are adjusted. Therefore, polysaccharides are often used in combination with superplasticisers. This can cause interactions, particularly when the stabilising agent shows a strong tendency to adsorb on particle surfaces. Adsorptive stabilising agents may reduce the amount of adsorbed superplasticisers, thus affecting both viscosity and yield stress, while non-adsorptive stabilising agents mainly affect the plastic viscosity independently of the superplasticiser. Due to the strong influence of superplasticisers on the yield stress, influences of the stabilising agent on the yield stress retreat into the background, so that their major effect is an increase of the viscosity. The paper provides a comprehensive overview of how different polysaccharide superplasticisers affect cementitious flowable systems and points out the challenges of the combined use of polysaccharides and superplasticisers. Based on rheometric experiments and Observations of the hydration process, time dependent effects on the workability as well as of the hydration of cement are presented. T2 - ICBBM 2015 - 1st International conference on bio-based building materials CY - Clermont-Ferrand, France DA - 22.06.2015 KW - Corrosion potential KW - Chloride migration KW - Electrical resistivity KW - Water absorption KW - Freeze-thaw PY - 2015 SN - 978-2-35158-154-4 N1 - Serientitel: Rilem proceedings – Series title: Rilem proceedings IS - PRO 99 SP - 100 EP - 106 AN - OPUS4-33582 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Efficiency of high performance concrete types incorporating bio-materials like rice husk ashes, cassava starch, lignosulfonate and sisal fibres T2 - ICBBM - 1st International Conference on Bio-Based Building Materials CY - Clermont-Ferrand, France DA - 2015-06-21 PY - 2015 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-33559 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Supplementary cementitious materials for sustainable and economic binders - European solutions compared to African solutions T2 - PACE-PTS Public Symposium on Cement and Concrete-related Issues for the African Market CY - Dar es Saalam, Tanzania DA - 2015-02-26 PY - 2015 AN - OPUS4-33562 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Mode of operation of polysaccharide stabilising agents in cement based systems and interactions with superplasticisers T2 - ICBBM - 1st International Conference on Bio-Based Materials CY - Clermont-Ferrand, France DA - 2015-06-21 PY - 2015 AN - OPUS4-33560 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Parameters that affect the workability of fresh concrete from nano- to centimetrescale T2 - 2015 SEMINAR SERIES No. 4 School of Civil & Environmental Engineering - University of the Witwatersand CY - Johannesburg, South Africa DA - 2015-05-14 PY - 2015 AN - OPUS4-33563 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Quality Control in Concrete Production - Introduction of control chart systems and the new concept according to EN 206 T2 - Public Seminar at the University of Dar es Salaam CY - Dar es Salaam, Tansania DA - 2014-10-28 PY - 2014 AN - OPUS4-32332 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram T1 - Steuerung der Mischung N2 - Seit den 1980er Jahren hat sich die Auswahl der zur Modifizierung des Verhaltens und der Leistungsfähigkeit von Beton erhältlichen Zusätzen erheblich verbreitet. Für viele Anwendungen ist die Steuerung der Rheologie PY - 2015 SN - 0014-7699 IS - 5 SP - 50 EP - 55 PB - Vincentz CY - Hannover AN - OPUS4-33577 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Frisch- und Festbetonprüfungen - ausgewählte Hinweise aus der Prüfpraxis T2 - Fachtagung "Prüfen und Erhalten von Stahlbeton" CY - Berlin, Deutschland DA - 2014-10-09 PY - 2014 AN - OPUS4-31688 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Sustainable cement extenders and SCMs T2 - Totally Concrete Expo CY - Johannesburg, South Africa DA - 2015-05-12 PY - 2015 AN - OPUS4-33564 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schmidt, Wolfram A1 - Leinitz, Sarah A1 - Mota, Berta A1 - Crasselt, Claudia ED - Liu, Jiaping ED - Wang, Ziming ED - Holland, Terence ED - Huang, Jing ED - Plank, Johann T1 - Influence of the aqueous phase of cement paste on the rheology in the presence of PCE N2 - The paper presents rheometric results and hydration curves for cementitious systems based on cement mixed with different aqueous phases at solid volume fraction of  = 0.45. The varied aqueous phases were deionized water, limewater, the filter residue of a cement paste mixed at w/c = 2.0, and the filtrate of cement paste at solid volume fraction of 0.45. Each cementitious system provided different amounts and sizes of particles formed in the aqueous phase. The pastes were observed with and without polycarboxylate ether based superplasticizer. It was observed that the presence of particles causes higher PCE saturation dosages to achieve a minimum value, but the minimum value is only affected in the case of large particles. In all cases with and without PCE, the presence of small particles causes increased plastic viscosity. In addition, with decreased number and size of hydrates in the aqueous phase the hydration was retarded, which was specifically pronounced in the presence of PCE KW - Aqueous phase of cement paste KW - Polycarboxylate ether KW - Rheology KW - Yield stress KW - Plastic viscosity KW - Heat of hydration KW - Syngenite KW - Solid volume fraction PY - 2018 SN - 978-1-64195-029-9 SP - SP-329-34, 428 EP - 443 PB - American Concrete Institute CY - Farmington Hill, Michigan AN - OPUS4-47107 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Correlation between setting, heat evolution, and deformations of cementitious binder systems depending on type and amount of superplasticizer N2 - Today polycarboxylate ether based superplasticizer (PCE) is commonly used in concrete technology when high flow properties and water reduction are specified. The ionic strength of the polymers’ backbones determines the adsorption behaviour of polymers on clinker and early hydration products. The amount of required polymers for specified flow properties and the performance over the time of casting is thus determined by the molecular structure of the superplasticizer. The time depending consumption of polycarboxylate ether polymers strongly affects the reaction of aluminates and sulphate ions as well as the hydration process in general. Hence, the choice of polymers for particular flow properties greatly affects the very early properties of cementitious materials such as setting, heat evolution and autogenous deformations. In order to better understand how PCEs influence the early properties, mixes from cement, limestone filler, viscosity modifying agent and water were varied with a high and a low charge density superplasticizer in differing amounts. Results are presented from measurements with an automatic Vicat device, an isothermal heat flow calorimeter, and shrinkage cones. Tests were conducted at 5, 20, and 30 °C. It is shown that in presence of PCE the final set correlates well with the inflexion point of the heat flow curve, which emphasises the interrelation between C-S-H formation and setting. No such clear correlation can be found for the initial set, which is attributed to the fact that the initial set is rather a rheological than a structural phenomenon, so that other effects overlap with C-S-H formation. The results demonstrate that for a given polymer concentration low charge density polymers yield earlier setting than high charge polymers. However, this influence is overridden by the influence of the total amount of polymers in a cementitious system. Since PCE is typically added according to rheological specifications, and low charge PCE typically requires higher amounts of polymers than high charge PCE for comparable flow performance, low charge PCE retards setting more than high charge PCE. The paper furthermore points out that there is no significant influence of the polymer type or amount on the early deformations. Since type and amount strongly affect the hydration, it is demonstrated that early setting causes higher strain after the final set. It is hence concluded that higher PCE solid contents reduce the risk of early cracks that occur at time of setting, when a solid structure has already been formed but without resistance against cracks yet. T2 - 13th International congress on the chemistry of cement CY - Madrid, Spain DA - 03.07.2011 KW - Polycarboxylate superplasticizer KW - Setting KW - Heat evolution KW - Autogenous deformation KW - Self-compacting concrete KW - Calorimetry PY - 2011 SN - 978-84-7292-400-0 SP - 384 EP - 391 AN - OPUS4-24097 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Akindahunsi, A. A. A1 - Schmidt, Wolfram A1 - Uzoegbo, H.C. A1 - Iyuke, S.E. ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - The influence of starches on some properties of concrete N2 - Starches and its derivatives are known to exhibit viscosity modifying characteristics. In an ongoing work, the influence of com and cassava starches on some properties of concrete such as compressive strength, heat of hydration and creep are examined. Various percentages (0.0, 0.5, 1.0, 1.5 and 2 %) of starches by weight of cement were added to concrete mixes prepared in the laboratory. Preliminary results of compressive strengths showed that both starches have some positive impact (e.g. there was 5.3 % increase in strength due to a 1 % addition of com starch by weight of cement in comparison to the control while cassava starch of the same percentage gave 4.9 % increase in strength) at certain percentages of starch addition to concrete at 28 days. The creep and hydration results shows the starch additions compares well and in some instance performs better. T2 - ACCTA - International conference on advances in cement and concrete technology in Africa 2013 CY - Johannesburg, South Africa DA - 28.01.2013 KW - Starches KW - Concrete KW - Compressive strength KW - Heat of hydration KW - Creep PY - 2013 SN - 978-3-9815360-3-4 SP - 637 EP - 645 AN - OPUS4-27756 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Einfluss der Polymerstruktur von Stabilisierern auf die Rheologie von selbstverdichtendem Beton und Mörtel T2 - 20. Kolloquium und Workshop "Rheologische Messungen an mineralischen Baustoffen" CY - Regensburg, Germany DA - 2011-03-01 PY - 2011 AN - OPUS4-23313 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -