TY - GEN A1 - Budnik, J. A1 - Betz, T. A1 - Fromm, A. A1 - Gerdes, A. A1 - Gerlach, J. A1 - Götz, M. A1 - Hintzen, W. A1 - Hüttl, R. A1 - Kämpfer, W. A1 - König, A. A1 - Kühner, S. A1 - Lohaus, L. A1 - Meng, Birgit A1 - Neumann, T. A1 - Patzer, M. A1 - Schaab, A. A1 - Schauerte, J. A1 - Siebert, B. A1 - Stephan, D. A1 - Tebbe, H. A1 - Wagner, J.-P. ED - Siebert, B. T1 - Chemischer Angriff auf Betonbauwerke - Bewertung des Angriffsgrads und geeignete Schutzprinzipien N2 - In verschiedenen Bereichen des Betonbaus ist Beton einem chemischen Angriff von außen ausgesetzt, der die Dauerhaftigkeit des betreffenden Bauteils bzw. des gesamten Bauwerks beeinträchtigen kann. Für einen chemischen Angriff in natürlichen Böden und Grundwässern bestehen normative Vorgaben in DIN 4030-1 [R10] bzw. DIN 1045-2 [R19], um den Angriffsgrad anhand der Art und Konzentration der angreifenden Stoffe in Expositionsklassen XA1 (schwach angreifend) bis XA3 (stark angreifend) einzustufen. Hinsichtlich weiterer maßgeblicher Einflussfaktoren wird an dieser Stelle nicht näher differenziert, ob und inwieweit die Regelungen für Böden und Grundwässer auch auf andere Bereiche mit chemischem Angriff auf Beton zu übertragen sind, ist stets im Einzelfall zu überprüfen. Ebenfalls sind die zu treffenden Maßnahmen über die Vorgaben der DIN EN 206-1/DIN 1045-2 [R19] hinaus anwendungsspezifisch festzulegen. Der Hauptausschuss Baustofftechnik (HABT) des DBV hat daher den Arbeitskreis "Chemischer Angriff auf Beton" beauftragt, dieses Merkblatt zu erarbeiten, das Hilfestellung bei der Bewertung einer projektspezifischen chemischen Angriffssituation auf Beton sowie bei der Planung und Ausführung von Schutzprinzipien leisten soll. KW - Beton KW - Betonangriff KW - Dauerhaftigkeit KW - Säureangriff KW - Sulfatangriff PY - 2014 SP - 1 EP - 101 PB - Eigenverlag Deutscher Beton- und Bautechnik-Verein e. V. CY - Berlin AN - OPUS4-44662 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schneider, M. A1 - Meng, Birgit T1 - Ressourcenschonung bei der Zementherstellung am Beispiel des Einsatzes von Hüttensand PY - 2002 SN - 3-7640-0426-6 SP - 10 EP - 14 PB - Verlag Bau + Technik CY - Düsseldorf AN - OPUS4-2069 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kühne, Hans-Carsten A1 - Maultzsch, Matthias A1 - Wolff, L. A1 - Meng, Birgit A1 - Raupach, M. ED - Maultzsch, M. T1 - Long-term performance of surface protection systems for concrete T2 - 11th International Congress on Polymers in Concrete (ICPIC `04) CY - Berlin, Germany DA - 2004-06-02 KW - Surface protection system KW - Concrete KW - Weathering KW - Water uptake KW - Freezethaw resistance KW - Chloride ingress KW - Carbonation KW - Hydrophobic treatment PY - 2004 SN - 3-00-013706-8 SP - 417 EP - 428 PB - BAM CY - Berlin AN - OPUS4-3602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, R. A1 - Fa, X. A1 - Yang, J. A1 - Cheng, Z. A1 - Ansari, A. A. A1 - Ou, Jun A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Preparation of core–shell structured NaYF4:Yb3+/ Tm3+@NaYF4:Yb3+/Er3+ nanoparticles with high sensitivity, low resolution and good reliability and application of their fluorescence temperature properties N2 - A series of NaYF4:Yb3+/Tm3+@NaYF4:Yb3+/Er3+ nanoparticles doped with Tm3+ and Er3+ were successfully prepared by the solvothermal method. Under 980 nm laser excitation, intense upconversion emission peaks of Tm3+ and Er3+ were observed for all samples. By doping Tm3+ and Er3+ with core–shell partitioning, not only a significant increase in fluorescence intensity could be achieved, but also simultaneous temperature measurements on multiple thermocouple energy levels could be realised. In addition, the temperature sensing performance of different thermocouple energy levels was also investigated, and it was found that the 3 F3 → 3 H6 and 1 G4 → 3 F4 thermocouple energy level pairs of Tm3+ were the best, with maximum absolute sensitivity and maximum relative sensitivity of up to 0.0250 K−1 and 2.155% K−1 respectively, higher than the sensitivity of other thermocouple energy levels. It has a temperature resolution of less than 0.0139 K, which is lower than that of most materials available today. By using this material as a probe to build a fiber optic temperature sensor platform, it was found to have reliable temperature measurement performance. KW - Flourescence KW - Optical probe KW - Sensor KW - Dye KW - Temperature KW - Nano KW - Particle KW - Upconversion KW - Lanthanide KW - Qantum yield KW - Quality assurance KW - Monitoring KW - Infrastructure PY - 2022 DO - https://doi.org/10.1039/d1ce01729b VL - 24 IS - 9 SP - 1752 EP - 1763 PB - RSC Publishing AN - OPUS4-54416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, T. A1 - Wang, J. A1 - Cheng, Z. A1 - Yang, J. A1 - Qiao, X. A1 - Wen, J. A1 - Resch-Genger, Ute A1 - Ou, J. T1 - Fluorescence temperature sensing of NaYF4:Yb3+/Tm3+@NaGdF4:Nd3+/Yb3+ nanoparticles at low and high temperatures N2 - NaYF4:Yb3+/Tm3+@NaGdF4:Nd3+/Yb3+ upconversion nanoparticles (UCNPs) were prepared using a solvothermal method, and the effects of key factors such as the content of sensitiser Nd 3+ and Yb3+ on their luminescence properties were investigated. The nanoparticles are homogeneous in size and well dispersed. Under 808 nm excitation, it can produce strong upconversion fluorescence. At the same time, the nanoparticles have good temperature-sensing properties at the thermally coupled energy levels of 700 nm and 646 nm for Tm3+. Using its fluorescence intensity ratio (FIR), accurate temperature measurements can be performed, and it has been found that it exhibits different temperature sensing properties in low and high-temperature regions. The maximum relative sensitivity was found to be 0.88% K-1 and 1.89% K-1 for the lowtemperature region of 285 K-345 K and the high-temperature region of 345 K-495 K. The nanoparticles were applied to the internal temperature measurement of lithium batteries and the actual high-temperature environment, respectively, and were found to have good temperature measurementt performance. KW - Fluorescence KW - Sensor KW - Temperature KW - Ratiometric KW - Lanthanide KW - Quantum yield KW - Integrating sphere spectroscopy KW - Absolute fluorescence KW - Quality assurance KW - Nano KW - Particle KW - Application KW - Upconversion nanoparticle PY - 2022 DO - https://doi.org/10.1088/1361-6528/ac84e4 SN - 1361-6528 VL - 33 IS - 34 SP - 1 EP - 15 PB - IOP Publishing CY - Bristol AN - OPUS4-55454 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, R. A1 - Fa, X. A1 - Yang, J. A1 - Cheng, Z. A1 - Qiao, X. A1 - Ou, J. A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Core−Shell NaYF4:Yb3+/Tm3+@NaGdF4:Ce3+/Eu3+ Nanoparticles for Upconversion and Downconversion Dual-Mode Fluorescence-Based Temperature Sensing N2 - NaYF4 as the core and NaGdF4 as the outer layer were used to obtain NaYF4:Yb3+/Tm3+@NaYF4:Ce3+/Eu3+ nanoparticles. Physical and morphological investigations indicated that the obtained nanoparticles were prepared in a hexagonal shape, with the NaGdF4 shell layer uniformly encapsulated on the NaYF4 core. Strong Tm3+ upconversion emission peaks were observed for a 980-nm-laser-excited sample, while strong Eu3+ downconversion emission peaks were observed for a 254-nm-laser-excited sample. By zonal doping of Tm3+ and Eu3+, their fluorescence intensity can be significantly increased; more importantly, simultaneous temperature measurements with dual-mode upconversion/downconversion can be achieved. The temperature measurement properties of the dual mode were also investigated, and it was discovered that the upconversion 3F3 → 3H6 and 1G4 → 3F4 thermocouple energy levels gave the best temperature measurements with maximum absolute and relative sensitivities of 0.0877 K−1 and 1.95% K−1, respectively, which are better than the current temperature measurement sensitivities of most rare-earth-based materials. This material was prepared as fiber-optic temperature-sensing probes to detect the temperature in the environment in real time and was found to perform excellently for temperature measurement. KW - Upconversion nanoparticle KW - Lanthanide KW - Sensing; temperature KW - Photophysics PY - 2022 DO - https://doi.org/10.1021/acsanm.2c01611 VL - 5 IS - 7 SP - 9266 EP - 9276 PB - American Chemical Society AN - OPUS4-55363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, T. A1 - Wang, J. A1 - Cheng, Z. A1 - Liu, Y. A1 - Qiao, X. A1 - Wen, J. A1 - Resch-Genger, Ute A1 - Long, W. A1 - Ou, J. T1 - NaYF4:Yb3+/Tm3+@NaYF4:Yb3+ Upconversion Nanoparticles for Optical Temperature Monitoring and Self-Heating in Photothermal Therapy N2 - The core−shell NaYF4:Yb3+/Tm3+@NaYF4:Yb3+ upconversion nanoparticles were successfully prepared by a solvothermal method, and a layer of mesoporous silica (mSiO2) was successfully coated on the periphery of the core−shell nanoparticles to transform their surface from lipophilic to hydrophilic, further expanding their applications in biological tissues. The physical phase, morphology, structure, and fluorescence properties were characterized by X-ray diffraction (XRD), field emission transmission electron microscopy (TEM), Fourier infrared spectroscopy (FT-IR), ζ potential analysis, and fluorescence spectroscopy. It was found that the material has a hexagonal structure with good hydrophilicity and emits intense fluorescence under 980 nm pump laser excitation. The non-contact temperature sensing performance of nanoparticles was evaluated by analyzing the upconversion fluorescence of Tm3+ (1G4 → 3F4 and 3F3 → 3H6) in the temperature range of 284−344 K. The absolute and relative sensitivities were found to be 0.0067 K−1 and 1.08 % K−1, respectively, with high-temperature measurement reliability and good temperature cycling performance. More importantly, its temperature measurement in phosphate-buffered saline (PBS) solution is accurate. In addition, the temperature of the cells can be increased by adjusting the laser power density and laser irradiation time. Therefore, an optical temperature sensing platform was built to realize the application of real-time monitoring of cancer cell temperature and the dual function of photothermal therapy. KW - Sensor KW - Temperature KW - Lanthanide KW - Tag KW - Fluorescence KW - Nanoparticles KW - Synthesis KW - Environment KW - Monitoring KW - Sensing KW - Nano KW - Life sciences KW - Upconversion PY - 2023 DO - https://doi.org/10.1021/acsanm.2c05110 VL - 6 IS - 1 SP - 759 EP - 771 PB - ACS Publications AN - OPUS4-57081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, T. A1 - Wang, J. A1 - Cheng, Z. A1 - Li, Z. A1 - Qiao, X. A1 - Wen, J. A1 - Resch-Genger, Ute A1 - Long, W. A1 - Ou, Jun T1 - Preparation of NaYF4: Yb3+/Tm3+@NaYF4@β-CD upconversion nanoparticles and application of their fluorescence temperature sensing properties N2 - The NaYF4: Yb3+/Tm3+@NaYF4@β-CD upconversion nanoparticles were successfully prepared by the solvothermal method, and the samples were pure hexagonal phase with good crystallinity and homogeneous size, asevidenced by XRD and TEM analysis. The FT-IR analysis shows that β-CD is successfully encapsulated on the surface of NaYF4: Yb3+/Tm3+@NaYF4 nanoparticles. The fluorescence intensity 3and lifetime were significantly increased after coating the inert layer on the surface of core nanoparticles. After further surface modification of β-CD, the fluorescence intensity and fluorescence lifetime were reduced, but the overall fluorescence was stronger. Temperature measurements using the fluorescence intensity ratio technique were found to have relatively low reliability and absolute sensitivity for temperature measurements using thermally coupled energy levels. However, the reliability of temperature measurements using non-thermally coupled energy levels is significantly higher and the absolute sensitivity is much higher than for measurements at thermally coupled levels. Since the maximum absolute sensitivity, maximum relative sensitivity and minimum temperature resolution are determined to be 0.1179 K-1, 2.19 %K􀀀 1 and 0.00019 K, respectively, NaYF4: Yb3+/Tm3+@NaYF4@β-CD upconversion nanoparticles are expected to be widely used in the biomedical field due to their feasibility, reliability, non-toxicity and harmlessness. KW - Upconversion KW - Surface modification KW - Fluorescence intensity ratio KW - Thermally coupled levels KW - Non-thermally coupled levels PY - 2023 DO - https://doi.org/10.1016/j.optmat.2022.113389 SN - 0925-3467 VL - 136 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-57105 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cheng, Z. A1 - Meng, M. A1 - Qiao, X. A1 - Liu, Y. A1 - Resch-Genger, Ute A1 - Ou, J. T1 - The synthesis of Er3+/Yb3+/K+ triple-doped NaYF4 phosphors and its high sensitivity optical thermometers at low power N2 - Optical Thermometry is popular among researchers because of its non-contact, high sensitivity, and fast measurement properties. In the present experiment, Er3+/Yb3+/K+ co-doped NaYF4 nanoparticles with different K+ concentrations were synthesized by solvothermal method, and the samples showed bright upconversion green emission under the excitation of a 980 nm laser. The powder X-ray diffractometer and transmission electron microscope were used to characterize the crystal structure and its surface morphology, respectively. The spectral characteristics of nanoparticles with K+ doping concentration from 10% to 30% (Molar ratio) were investigated by fluorescence spectroscopy, and it was observed that the fluorescence intensity reached the maximum at the K+ concentration of 20%, after which the intensity weakened when the K+ content continued to increase. According to the dependence between the luminescence intensity of the sample and the laser power density and fluorescence lifetime, the intrinsic mechanism was carefully investigated. Temperature-dependent spectra of the samples were recorded in the temperature range of 315–495 K, and the maximum values of absolute sensitivity (Sa) and relative sensitivity (Sr) were measured at 0.0041 K−1 (455 K) and 0.9220%K−1 (315 K). The experimental results show that K+/Er3+/Yb3+ triple-doped NaYF4 green fluorescent nanoparticles (GFNs) have good prospects for applications in display devices, temperature sensing, and other fields. KW - K+ doped KW - Upconversion luminescence KW - Optical temperature sensing KW - Thermal coupling energy level PY - 2023 DO - https://doi.org/10.1016/j.jallcom.2022.168299 VL - 937 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-57106 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Przondziono, R. A1 - Timothy, J.J. A1 - Nguyen, M. A1 - Weise, Frank A1 - Breitenbücher, R. A1 - Meschke, G. A1 - Meng, Birgit T1 - Vorschädigungen in Beton infolge zyklischer Beanspruchungen und deren Auswirkung auf Transportprozesse im Hinblick auf eine schädigende AKR N2 - Auf Grundlage der Zielsetzung der Forschergruppe 1498 beschäftigt sich dieser Beitrag mit den Auswirkungen einer zyklischen mechanischen Belastung im Vierpunktbiegeversuch auf das Transportverhalten in Betongefüge. Hierzu wurde zunächst die Degradation des Mikrogefüges mittels Ultraschallmessungen sowie rissmikroskopischen Untersuchungen an Dünnschliffen charakterisiert. Mit dem Ziel der numerischen Modellbildung wurden Untersuchungen zum Wassereindringverhalten durchgeführt. Es wurden u. a. das Wassereindringverhalten über die Zeit und der Einfluss von Vorschädigungen experimentell geprüft. Basierend auf den gewonnenen Erkenntnissen zu den Einzelprozessen des Ionentransports in poröses Gefüge wurde ein mikromechanisches Mehrskalenmodell entwickelt, welches es ermöglicht, die Wirkung der Vorschädigung auf gekoppelte Feuchte- und Ionentransportprozesse vorherzusagen. Das Modell berücksichtigt die Topologie und räumliche Verteilung der Mikrorisse und deren Einfluss auf die Ionendiffusivität. Die numerische Simulation liefert bei anisotroper Verteilung der Mikrorisse eine erhöhte Alkali-Eindringtiefe. ---------------------------------------------------------------------------------------------------------------------------------- According to the goals of the research group 1498, this paper deals with the effects of cyclic flexural loading in a four-point bending test on the fluid transport processes within a concrete structure. Therefore, the degradation of the microstructure is characterized through ultrasonic wave measurements as well as microscopic crack analysis. In order to numerically model these processes, experiments on the penetration behavior of water into the concrete were carried out. The penetration behavior over time as well as the influence of degradation on the water transport were investigated. To predict the influence of concrete degradation on alkali diffusivity, a multi-scale continuum micromechanics model is incorporated into the numerical model, which accounts for the topology and the three-dimensional distribution of microcracks. As expected, the numerical simulation predicts larger alkali-penetration in pre-damaged concrete. Regarding the micro-crack distribution, an anisotropic distribution of micro-cracks tangential to the direction of the alkali and water flux increases their penetration depth. KW - Alkali-Kieselsäure-Reaktion KW - Baustoffe KW - Degradation KW - Ionentransport KW - Mikromechanik KW - Modellierung KW - Straßenbeton KW - Transportprozesse KW - Vorschädigung KW - zyklische Belastung KW - Korrosion KW - Versuche KW - Fahrbahn KW - Cyclic loading KW - Transport process KW - Schädigende AKR KW - ASR damage PY - 2015 DO - https://doi.org/10.1002/best.201400095 SN - 0005-9900 SN - 1437-1006 VL - 110 IS - 1 SP - 3 EP - 12 PB - Ernst CY - Berlin AN - OPUS4-33039 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Budnik, J. A1 - Betz, T. A1 - Brameshuber, W. A1 - Fromm, A. A1 - Gerdes, A. A1 - Gerlach, J. A1 - Götz, M. A1 - Hart, R. A1 - Heese, C. A1 - Hintzen, W. A1 - Hüttl, R. A1 - Kämpfer, W. A1 - König, A. A1 - Kühner, S. A1 - Lohaus, L. A1 - Meng, Birgit A1 - Neumann, T. A1 - Remus, R. A1 - Schaab, A. A1 - Schäffel, P. A1 - Schauerte, J. A1 - Schönborn, A. A1 - Siebert, B. A1 - Stephan, D. A1 - Tebbe, H. A1 - Wagner, J.-P. ED - Siebert, B. T1 - Chemischer Angriff auf Beton - Empfehlungen zur Prüfung und Bewertung N2 - ln den letzten Jahren wurden diverse Prüfverfahren und Methoden entwickelt, um die Leistungsfähigkeit von Beton bzw. Bindemittel hinsichtlich des Widerstands gegenüber betonaggressiven Einwirkungen beurteilen zu können. Ein wesentliches Ziel von Prüfverfahren zur Beurteilung der Dauerhaftigkeit von Baustoffen ist, die im Laufe der Nutzungsdauer zu erwartenden Einwirkungen auf den Baustoff realitätsnah abzubilden. Dazu sind die Prüfparameter auf die im jeweiligen Anwendungsbereich vorherrschenden Umgebungs- und Randbedingungen anzupassen. Daneben sind auch die Bewertungskriterien individuell unter Berücksichtigung der im Einzelfall geforderten Nutzungsdauer eines Bauwerks festzulegen. Eine systematische Zuordnung von adäquaten Prüfverfahren bzw. Prüfparametem und Bewertungskriterien für die verschiedenen Anwendungsbereiche im Betonbau, in denen betonaggressive Einwirkungen auftreten, ist mit Ausnahme von Einzelfällen bislang nicht vorhanden. Daneben stellt sich in der Praxis immer wieder das Problem, das Angriffspotenzial der Umgebung eines Bauwerks (prüftechnisch) zu erfassen und zu bewerten. Der Hauptausschuss Baustofftechnik des DBV hat daher den Arbeitskreis „Chemischer Angriff auf Beton“ beauftragt, dieses Merkblatt zu erarbeiten, das auf Basis von einschlägigen Erfahrungen der Baupraxis und wissenschaftlichen Erkenntnissen Grundsätze und bewährte Methoden zur Beurteilung der Einwirkungs- und Widerstandsseite beim chemischen Angriff auf Beton aufzeigt und diesbezüglich Hinweise für verschiedene Anwendungsbereiche im Betonbau liefert. KW - Beton KW - Betonangriff KW - Dauerhaftigkeit KW - Säureangriff PY - 2017 SP - 1 EP - 65 PB - Eigenverlag Deutscher Beton- und Bautechnik-Verein e. V. CY - Berlin AN - OPUS4-44663 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tan, M. A1 - Monks, Melissa-Jane A1 - Huang, D. A1 - Meng, Y. A1 - Chen, X. A1 - Zhou, Y A1 - Lom, S.-F. A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Chen, G. T1 - Efficient sub-15 nm cubic-phase core/Shell upconversion nanoparticles as reporters for ensemble and single particle studies† N2 - Single particle imaging of upconversion nanoparticles (UCNPs) has typically been realized using hexagonal (β) phase lanthanide-doped sodium yttrium fluoride (NaYF4) materials, the upconversion luminescence (UCL) of which saturates at power densities (P) of several hundred W cm−2 under 980 nm nearinfrared (NIR) excitation. Cubic (α) phase UCNPs have been mostly neglected because of their commonly observed lower UCL efficiency at comparable P in ensemble level studies. Here, we describe a set of sub-15 nm ytterbium-enriched α-NaYbF4:Er3+@CaF2 core/shell UCNPs doped with varying Er3+ concentrations (5–25%), studied over a wide P range of ∼8–105 W cm−2, which emit intense UCL even at a low P of 10 W cm−2 and also saturate at relatively low P. The highest upconversion quantum yield (ΦUC) and the highest particle brightness were obtained for an Er3+ dopant concentration of 12%, reaching the highest ΦUC of 0.77% at a saturation power density (Psat) of 110 W cm−2. These 12%Er3+-doped core/shell UCNPs were also the brightest UCNPs among this series under microscopic conditions at high P of ∼102–105 W cm−2 as demonstrated by imaging studies at the single particle level. Our results underline the potential applicability of the described sub-15 nm cubic-phase core/shell UCNPs for ensemble- and single particle- level bioimaging. KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - Surface chemistry KW - Single particle KW - Brightness PY - 2020 DO - https://doi.org/10.1039/d0nr02172e VL - 12 IS - 19 SP - 10592 EP - 10599 PB - Nanoscale AN - OPUS4-50908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krütt, Enno A1 - Wallau, Wilma A1 - Meng, Birgit A1 - Greim, M. A1 - Pirskawetz, Stephan T1 - Automatisierte AKR-Prüfung im 60 °C-Betonversuch T1 - Automated ASR Concrete Prism Testing at 60 degrees C N2 - Der 60 °C-Betonversuch ist eine in Deutschland und international verbreitete Methode um die Empfindlichkeit von Gesteinskörnungen und Betonen hinsichtlich einer Alkali-Kieselsäure Reaktion (AKR) zu prüfen. Dieser Beitrag stellt eine neuentwickelte automatisierte Variante der Prüfmethode in einem Minireaktor vor. Dabei werden die Dehnungen von Betonprismen nicht, wie beim konventionellen Test manuell, sondern automatisch in entsprechend ausgerüsteten Prüfbehältern gemessen. Neben einer Reduzierung des Messaufwands bringt die automatisierte Prüfung im Minireaktor weitere Vorteile. Die Dehnungssignale werden, anders als bei der konventionellen Messung, quasi-kontinuierlich aufgezeichnet und bilden das Expansionsverhalten der Prismen detailliert ab. Außerdem bleiben Unterbrechungen der AKR-provozierenden Lagerung aus, die bei der konventionellen Prüfung notwendig sind. Im Beitrag werden die automatisierte und konventionelle Prüfung anhand der Dehnungen von Prismen zweier Gesteinskörnungen verglichen. In Übereinstimmung mit vorhergehenden Untersuchungen sind im Minireaktor gemessene Dehnungen systematisch kleiner als manuell gemessene. Als mögliche Ursache werden Unterschiede im Auslaugverhalten experimentell untersucht. Zur Überprüfung der Einstufung der zwei Gesteinskörnungen erfolgen außerdem Referenzprüfungen in der Nebelkammerlagerung bei 40 °C. N2 - The Concrete Prism Test at 60 °C (60 °C-CPT) is a common method to evaluate the susceptibility of concrete and aggregates to the Alkali-Silica Reaction (ASR). This paper presents a new device for an automated version of the 60 °C-CPT. The system monitors the expansion of concrete prism automatically. Compared to the conventional test method, effort and time consumption are notably reduced. The nearly continuous recording of expansion signals allows for studying of ASR-mechanisms in more detail than the conventional test. In addition, the interruptions of ASR-provoking storage, necessary for manual measurements, are avoided. The presented study compares results of conventional and automated testing of two types of aggregate. In accordance with previous findings, continuously stored prisms generally expand less than the conventionally tested prisms. To find a possible explanation, differences in leaching of alkali from the concrete prisms were quantified. For verifying the alkali-reactivity of the two aggregates, they were also classified in the fog chamber test at 40 °C, the German reference method. KW - Baustoffe KW - AKR KW - 60 °C-Betonversuch KW - Automatische Dehnungsmessung KW - Auslaugung KW - Building Materials KW - ASR KW - Concrete Prism Test at 60 °C KW - Automated expansion measurement KW - Leaching of alkalis PY - 2019 DO - https://doi.org/10.1002/best.201900040 SN - 1437-1006 SN - 0005-9900 VL - 114. Jahrgang IS - 12 SP - 911 EP - 918 PB - Ernst & Sohn AN - OPUS4-50062 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, R. A1 - Zhenlong, F. A1 - Yang, J. A1 - Ansari, A. A1 - Ou, Jun A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Retracted article: Effect of Ca2+ doping on the upconversion luminescence properties of NaYF4:Yb3+/Tm3+ nanoparticles and study of its temperature measurement performance N2 - A solvothermal method was used to prepare a series of Yb3+/Tm3+/Ca2+ co-doped NaYF4 nanoparticles with different Ca2+ contents. Strong upconversion blue fluorescence could be observed under 980 nm laser excitation of the samples. The effect of different Ca2+ contents on the luminescence intensity was investigated, and it was found that the UV-vis upconversion luminescence increased and then decreased with an increasing Ca2+ concentration during the increase of the Ca2+ content from 0 mol% to 25 mol%, reaching the strongest fluorescence at 15 mol%, which was up to about 28 times stronger than that without Ca2+ doping. Furthermore, the mechanism was investigated, and it was found that the doping of Ca2+ disrupted the symmetry of the crystal field, resulting in a significant enhancement of the overall fluorescence. Applied to fluorescence intensity ratio thermometry, the absolute and relative sensitivities are as high as 0.0418 K−1 and 2.31% K−1, respectively, with a minimum temperature resolution of 0.0129 K. KW - Sensor KW - Temperature KW - Lanthanide KW - Luminescence KW - Nanoparticles KW - Upconversion KW - Advanced materials PY - 2022 DO - https://doi.org/10.1039/D2CE00562J SN - 1466-8033 VL - 24 IS - 27 SP - 4887 EP - 4898 PB - Royal Society of Chemistry CY - London AN - OPUS4-56952 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ruyle, B. A1 - Pickard, H. A1 - Schultes, L. A1 - Fredriksson, F. A1 - Heffernan, A. A1 - Knappe, D. A1 - Lord, H. A1 - Meng, P. A1 - Mills, M. A1 - Ndungu, K. A1 - Roesch, Philipp A1 - Rundberget, J.T. A1 - Tettenhorst, D. A1 - Van Buren, J. A1 - Vogel, Christian A1 - Westerman, D. A1 - Yeung, L. A1 - Sunderland, E. T1 - Interlaboratory Comparison of Extractable Organofluorine Measurements in Groundwater and Eel (Anguilla rostrata): Recommendations for Methods Standardization N2 - Research on per- and polyfluoroalkyl substances (PFAS) frequently incorporates organofluorine measurements, particularly because they could support a class-based approach to regulation. However, standardized methods for organofluorine analysis in a broad suite of matrices are currently unavailable, including a method for extractable organofluorine (EOF) measured using combustion ion chromatography (CIC). Here, we report the results of an international interlaboratory comparison. Seven laboratories representing academia, government, and the private sector measured paired EOF and PFAS concentrations in groundwater and eel (Anguilla rostrata) from a site contaminated by aqueous film-forming foam. Among all laboratories, targeted PFAS could not explain all EOF in groundwater but accounted for most EOF in eel. EOF results from all laboratories for at least one replicate extract fell within one standard deviation of the interlaboratory mean for groundwater and five out of seven laboratories for eel. PFAS spike mixture recoveries for EOF measurements in groundwater and eel were close to the criterion (±30%) for standardized targeted PFAS methods. Instrumental operation of the CIC such as replicate sample injections was a major source of measurement uncertainty. Blank contamination and incomplete inorganic fluorine removal may introduce additional uncertainties. To elucidate the presence of unknown organofluorine using paired EOF and PFAS measurements, we recommend that analysts carefully consider confounding methodological uncertainties such as differences in precision between measurements, data processing steps such as blank subtraction and replicate analyses, and the relative recoveries of PFAS and other fluorine compounds. KW - Extractable organic fluorine KW - Per- and Polyfluoroalkyl substances (PFAS) KW - Combustion ion chromatography (CIC) PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-587726 DO - https://doi.org/10.1021/acs.est.3c04560 SN - 0013-936X VL - 57 IS - 48 SP - 20159 EP - 20168 PB - American Chemical Society (ACS) AN - OPUS4-58772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Meng, M. A1 - Zhang, R. A1 - Cheng, Z. A1 - Fa, X. A1 - Yang, J. A1 - Ansari, A. A. A1 - Ou, Jun A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Retraction: Effect of Ca2+ doping on the upconversion luminescence properties of NaYF4:Yb3+/Tm3+ nanoparticles and study of its temperature measurement performance N2 - Retraction of "Effect of Ca2+ doping on the upconversion luminescence properties of NaYF4:Yb3+/Tm3+ nanoparticles and study of its temperature measurement performance" by Mingzhou Meng et al., CrystEngComm, 2022, 24, 4887–4898, https://doi.org/10.1039/D2CE00562J. The Royal Society of Chemistry, with the agreement of the authors, hereby wholly retracts this CrystEngComm article due to concerns with the reliability of the data. PY - 2023 DO - https://doi.org/10.1039/d3ce90111d SN - 1466-8033 VL - 25 IS - 33 SP - 4768 PB - Royal Society of Chemistry CY - London AN - OPUS4-58494 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Hauer, B. A1 - Pierkes, R. A1 - Schäfer, S. A1 - Seidel, M. A1 - Herbst, Tristan A1 - Rübner, Katrin A1 - Meng, Birgit T1 - Verbundforschungsvorhaben 'Nachhaltig Bauen mit Beton' - Potenziale des Sekundärstoffeinsatzes im Betonbau - Teilprojekt B N2 - Die Nutzung und Weiterverarbeitung von Sekundärstoffen kann in der Baustoffherstellung einen Beitrag zum nachhaltigen Bauen leisten. Im Rahmen des Teilprojekts B wurde die Bewertung dieser Potenziale anhand von Beispielen ausgebaut und verifiziert. Die Basis dieser Bewertungsgrundlage ist die Erfüllung der grundlegenden technischen Anforderungen (ökobilanzielle Indikatoren, vergleichende ökobilanzielle Betrachtung). Im Teilprojekt E geht es um die Freisetzung umweltrelevanter Stoffe aus zementgebundenen Baustoffen. Überprüft werden sollte die Übereinstimmung zwischen Laborergebnissen, Modellierungen und realen Grundwasserkonzentrationen. Es wurden Schlitzwände errichtet, die in den Grundwasserleiter einbinden und umweltrelevante Parameter bestimmt. Grundsätzlich hat sich selbst bei Großbaustellen nur eine geringe Beeinflussung der Grundwasserqualität durch Beton ergeben. KW - Sekundärstoff KW - Zement KW - Beton KW - Nachhaltigkeit KW - Bewertung KW - Recycling KW - Betonbrechsand KW - Müllverbrennungsasche KW - Kesselsand KW - Ökobilanz PY - 2011 SN - 978-3-410-65094-2 SN - 0171-7197 IS - 584 SP - 1 EP - 151 PB - Beuth CY - Berlin AN - OPUS4-25982 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Sonebi, M. A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Diouri, A. ED - Khachani, N. ED - Alami Talbi, M. ED - Ait Brahim, L. ED - Bahi, L. T1 - Rheology modifying admixtures: The key to innovation in concrete technology - a general overview and implications for Africa N2 - Innovative admixture technology has significantly widened up the ränge of possibilities of concrete engineers. For many decades the water to cement ratio (w/c) was the major influencing factor for the performance of concrete. Due to the need to adjust a consistency, which still allowed reasonable workability, the w/c was typically significantly higher than technologically reasonable. Rheology modifying admixtures Support adjusting the concrete consistency largely independent of the w/c. It was only after the invention of the first superplasticizers that modern concrete technology significantly evolved in terms of flowability, strength, and durability, and only due to the steady evolution of the technology modern innovations, such as Self-Compacting Concrete, Ultra-High-Performance Concrete, or Engineered Cementitious Composites were made possible. Today’s superplasticizers are extremely versatile and can be adjusted to individual technological specifications. However, the other side of the coin of versatility is that cementitious Systems incorporating superplasticizers have become more sensitive against environmental influences, such as the environmental temperature, which may cause unwanted effects or demand for supplementary admixture use such as stabilizing admixtures. Hence, concrete mixture composition with admixtures demands for a high level of expertise and offen there is lack of awareness about the mode of Operation of rheology modifying admixtures among concrete technologists. The paper gives a comprehensive overview about rheology modifying admixtures such as superplasticizers or stabilizing agents, and how they can be used depending upon the application in the most favourable way. Based on experiences with the sub-Saharan African concreting boundary conditions, which exhibit many challenges in terms of environmental boundary conditions and construction site logistics, conclusions are finally drawn, how admixtures can be used in the most beneficial way to improve the concrete casting Situation. T2 - CMSS 2013 - International congress on materials & structural stability - Building up sustainable materials & constructions CY - Rabat, Morocco DA - 27.11.2013 KW - Rheology KW - Superplasticizers KW - Stabilising agents PY - 2013 SN - 978-9954-32-689-3 SP - 1 EP - 6 AN - OPUS4-30040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Sonebi, M. A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Rheology modifying admixtures: The key to innovation in concrete technology - a general overview and implications for Africa N2 - Innovative admixture technology has significantly widened up the ränge of possibilities of concrete engineers. For many decades the water to cement ratio (w/c) was the major influencing factor for the performance of concrete. Due to the need to adjust a consistency, which still allowed reasonable workability, the w/c was typically significantly higher than technologically reasonable. Rheology modifying admixtures Support adjusting the concrete consistency largely independent of the w/c. It was only after the invention of the first superplasticizers that modern concrete technology significantly evolved in terms of flowability, strength, and durability, and only due to the steady evolution of the technology modern innovations, such as Self-Compacting Concrete, Ultra-High-Performance Concrete, or Engineered Cementitious Composites were made possible. Today’s superplasticizers are extremely versatile and can be adjusted to individual technologicalspecifications. However, the other side of the coin of versatility is that cementitious Systems incorporating superplasticizers have become more sensitive against environmental influences, such as the environmental temperature, which may cause unwanted effects or demand for supplementary admixture use such as stabilizing admixtures. Hence, concrete mixture composition with admixtures demands for a high level of expertise and offen there is lack of awareness about the mode of Operation of rheology modifying admixtures among concrete technologists. The paper gives a comprehensive overview about rheology modifying admixtures such as superplasticizers or stabilizing agents, and how they can be used depending upon the application in the most favourable way. Based on experiences with the sub-Saharan African concreting boundary conditions, which exhibit many challenges in terms of environmental boundary conditions and construction site logistics, conclusions are finally drawn, how admixtures can be used in the most beneficial way to improve the concrete casting Situation. KW - Rheology KW - Admixtures KW - Concrete KW - Superplasticizers KW - Polycarboxylate ether KW - Viscosity modifying agents PY - 2013 SN - 2224-3224 SN - 2225-0956 VL - 5 SP - 115 EP - 120 PB - International Institute for Conservation of Historic and Artistic Works CY - New York, NY, USA AN - OPUS4-30948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Giebson, C. A1 - Voland, Katja A1 - Ludwig, H.-M. A1 - Meng, Birgit T1 - Untersuchungen zur Alkali-Kieselsäure-Reaktion in vorgeschädigten Fahrbahndeckenbetonen N2 - In Betonbauteilen unter gleichzeitiger zyklischer Beanspruchung und externer Alkalizufuhr ist die Gefahr von Schäden infolge oder unter Mitwirkung einer Alkali-Kieselsäure-Reaktion (AKR) besonders hoch. Dies betrifft insbesondere Fahrbahndecken, bedingt durch den zunehmenden Schwerlastverkehr und den winterlichen Auftrag des Enteisungsmittels NaCl. Speziell die Rolle einer mechanischen Vorschädigung des Betons infolge der Verkehrsbeanspruchungen auf den Ablauf einer AKR ist dabei aber noch nicht in ausreichendem Umfang geklärt. Ein Teil der dazu seit 2012 durchgeführten Untersuchungen im Rahmen der DFG-Forschergruppe 1498 soll im Folgenden vorgestellt werden. Es zeigte sich, dass eine AKR in definiert mechanisch vorgeschädigten Betonprobekörpern mit alkalireaktiven Gesteinskörnungen und unter äußerer Alkalizufuhr vor allem früher beginnt als in äquivalenten Probekörpern ohne Vorschädigung. Grund dafür ist das schnellere und tiefere Eindringen von Wasser und insbesondere gelöstem NaCl in den Beton, wodurch Na-Ionen als Reaktionspartner für eine AKR früher und langfristig auch in größerer Menge verfügbar sind.------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ In concrete elements, simultaneously subjected to cyclic loadings and external alkalis, the risk for damages caused by or under participation of an alkali-silica reaction (ASR) is particularly high. This concerns especially concrete pavements due to the increasing heavy load traffic and the wintry application of NaCl deicer. Notably the role of a mechanical pre-damage of concrete caused by traffic loadings on the course of the ASR is largely unclear. A part of the investigations that has been conducted since 2012 into this issue within the scope of the DFG (German research foundation) funded research group 1498 shall be introduced in the following. It was evident that an ASR in defined mechanically pre-damaged concrete prisms with alkali-reactive aggregates and under an external supply of alkalis started earlier than in equal prisms without a pre-damage. The reason for this is the faster and deeper ingress of water and particularly of dissolved NaCl into the concrete, by what Na ions as reaction partner for an ASR are available earlier and, in the long-term, in greater amounts too. KW - Alkali-Kieselsäure-Reaktion KW - AKR KW - Äußere Alkalizufuhr KW - Fahrbahndeckenbetone KW - Mechanische Vorschädigung KW - Versuche KW - Korrosion KW - Baustoff PY - 2015 DO - https://doi.org/10.1002/best.201400094 SN - 0005-9900 SN - 1437-1006 VL - 110 IS - 1 SP - 13 EP - 21 PB - Ernst CY - Berlin AN - OPUS4-32431 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Giebson, C. A1 - Voland, K. A1 - Ludwig, H.-M. A1 - Meng, Birgit T1 - Alkali-silica reaction performance testing of concrete considering external alkalis and preexisting microcrack N2 - In concrete elements, simultaneously subjected to cyclic loadings and external alkalis, the risk for damage caused by or under participation of an alkali-silica reaction (ASR) is particularly high. This is of particular concern for concrete pavements due to the increasing heavy vehicle traffic and the application of sodium chloride (NaCl) de-icer during winter. Since 2004, the climate simulation concrete prism test (CS-CPT) has been used successfully to evaluate job mixtures for pavements by considering the impact of alkali-containing de-icers. However, the role of mechanical predamage on ASR is largely unclear. In a joint research project, the CS-CPT has been used to investigate the influence of preexisting microcracks on ASR. It was evident that an ASR initiated earlier in the predamaged concrete prisms due to the more rapid ingress of NaCl solution through the microcracks. KW - Alkali-silica reaction KW - Climate simulation concrete prism test KW - External alkalis KW - Laser-induced breakdown spectroscopy KW - Microcracks KW - Pavement concrete PY - 2017 DO - https://doi.org/10.1002/suco.201600173 SN - 1464-4177 SN - 1751-7648 VL - 18 IS - 4 SP - 528 EP - 538 PB - Ernst & Sohn AN - OPUS4-42574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schlegel, M.C. A1 - Stroh, Julia A1 - Malaga, K. A1 - Meng, Birgit A1 - Panne, Ulrich A1 - Emmerling, Franziska T1 - Pathway of a damaging mechanism - Analyzing chloride attack by synchrotron based X-ray diffraction N2 - Typically, the changes of the phase compositions due to the chemical attack are studied in-situ only by chemical analysis or microscopy. In this study, the chloride transport and binding in the cement matrix in different cementitious materials was analyzed by synchrotron based X-ray diffraction (SyXRD) and energy dispersive X-ray spectroscopy (EDX). Sample materials consisting of cement paste were embedded in high concentrated sodium chloride solution over different time spans. Afterwards, the phase and chemical compositions were determined. The high spatial resolution and the information about the chloride distribution offer a detailed view of chloride binding in the cement matrix and allow the conclusions about the degradation mechanisms. The results are discussed related to the influence of different supplementary cementitious materials on the damaging mechanism. KW - Portland cement KW - In-situ KW - X-Ray diffraction KW - EDX KW - Durability KW - Chloride attack PY - 2015 DO - https://doi.org/10.1016/j.solidstatesciences.2015.03.021 SN - 1293-2558 SN - 1873-3085 VL - 44 SP - 45 EP - 54 PB - Elsevier Masson SAS CY - Amsterdam AN - OPUS4-33171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -