TY - CONF A1 - Sonebi, M. A1 - Khatib, J. A1 - Schmidt, Wolfram ED - Diouri, A. ED - Khachani, N. ED - Alami Talbi, M. ED - Ait Brahim, L. ED - Bahi, L. T1 - Influence of the type of viscosity-modifying admixtures and metakaolin on the rheology of grouts N2 - The Viscosity-modifying admixtures (VMAs) contribute to the control of the rheology of grouts and are used to enhance plastic viscosity, cohesion, stability, and resistance to bleeding of cement-based systems. This paper reports the results of an investigation on the effect of type of VMAs, namely two types of diutan gums and a welan gum and metakaolin (MTK), plus a superplasticiser, on the rheology behaviour of cement grouts. All mixes were made with polycarboxylic superplasticiser at 0.6% and 0.9%. The dosages of VMAs were 0.05%, and 0.10%, with a fixed water-to-binder ratio of 0.40. The investigated fresh properties of the grouts included the mini-slump flow, plate cohesion, and rheology parameters: namely yield value and plastic viscosity. The rheological parameters were obtained using a vane viscometer. Control grouts (with and without superplasticiser and VMA) were also tested and compared to mixes containing VMAs. The results indicated that the incorporation of MTK reduced the fluidity and increased the plate cohesion and yield stress, and plastic viscosity due to the higher surface area of MTK. The diutan gum grouts improved the grout fresh properties and rheology compared to the welan gum grouts. T2 - CMSS 2013 - International congress on materials & structural stability - Building up sustainable materials & constructions CY - Rabat, Morocco DA - 27.11.2013 KW - Viscosity modifying agent KW - Metakaolin KW - Diutan gum KW - Welan gum KW - Rheology PY - 2013 SN - 978-9954-32-689-3 SP - 1 EP - 6 AN - OPUS4-30041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kumaran, G.S. A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Florea, M.V.A. A1 - Nibasumba, P. ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - A study on sustainable energy for cement industries in Rwanda N2 - Rwanda is a landlocked country in the East Africa. It is surrounded by Uganda, Tanzania, Congo and Burundi. Rwanda is a fast developing country and it spends most of its revenues to import fossil fuels from either through Mombasa Port in Kenya or Dar es Salaam port in Tanzania because the energy production in Rwanda is not sufficient for its development. Transporting the fuels from these ports, add on to the cost of all materials, cement industry being no exception. There are three cement companies in Rwanda. The cement industries could not run in full production due to the shortage of fuel. Moreover, Rwanda is importing all the construction materials such as steel, roofing materials, etc from its neighbouring countries. This increases the cost of construction and the common man find difficult to own a house. In order to sustain the energy needs of Rwanda, different sources of energies should be focused. They are Peat, Geothermal, Methane gas, solar, wind, waste materials and Municipal wastes. Without affecting the environment, there is an urgent need to find a solution on sustainable energy in Rwanda. This paper discusses about the possible sources of energy in Rwanda which will improve the energy sustainability and turn the economy of Rwanda. T2 - ACCTA - International conference on advances in cement and concrete technology in Africa 2013 CY - Johannesburg, South Africa DA - 28.01.2013 KW - Biomass KW - Cement production KW - Peat KW - Energy sustainability PY - 2013 SN - 978-3-9815360-3-4 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. SP - 1169 EP - 1175 AN - OPUS4-27766 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Patrick A1 - Gluth, Gregor A1 - Schmidt, Wolfram A1 - Astorg, Adéle A1 - Kühne, Hans-Carsten A1 - Brouwers, H.J.H. T1 - Rheological properties of microsilica and sodium aluminate based one-part geopolymers compared to ordinary Portland cement N2 - One-part (“just-add-water”) geopolymers are a new dass of mineral binders that are produced without the use of alkaline activating Solutions. Compared to conventional geopolymers, i. e. those activated by highly alkaline Solutions, much less is known about the one-part geopolymers ’ microstructure and with regard to their rheology. In this work, the rheology of one-part geopolymers, produced from microsilica and sodium aluminate, with several SiO-flACOiratios and two different water/binder-ratios (w/b) were investigated qualitatively with a viscometer (mortar measuring cellj. Absolute values of plastic viscosity and yield stress were determined with a double gap measuring cell. In addition spread flow tests were conducted. The aim was to classify the early behavior of geopolymer pastes and to compare it to ordinary Portland cement (CEM 142.5 R) pastes. At moderate to high shear rates, the measured flow curves cotdd be fltted well by the Bingham model. With increasing silica content the yield stress increased. Up to a certain SiOi/Al2O3-ratio viscosity also increased with increasing silica content; however, at higher silica/alumina-ratios the viscosity decreased again. Higher w/b-ratios caused lower yield stresses and viscosities. Compared to Portland cement pastes, most of the considered geopolymers were signiflcantly stiffer. The results were further Interpreted in terms of pore solution viscosity and volume-based water to binder ratios (w/b) of the geopolymer pastes. T2 - 5th International Conference Non-Traditional Cement & Concrete CY - Brno, Czech Republic DA - 16.06.2014 KW - Alkali-activated binders KW - One-part geopolymers KW - Rheology PY - 2014 SN - 978-80-214-4867-4 SP - 71 EP - 74 AN - OPUS4-31159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Lu, Z. A1 - Becker, S. A1 - Leinitz, Sarah A1 - von Klitzing, R. A1 - Schmidt, Wolfram A1 - Stephan, D. ED - Mechtcherine, V. ED - Khayat, K. ED - Secrieru, E. T1 - Rheological properties of silica beads in the presence of different polymers and electrolyte N2 - Properties of interstitial liquid phase in cement paste, including the species and concentrations of polymers and ion etc., play an important role for the rheological properties of cementitious materials. In order to better understand their effect, an inert model substance, spherical silica beads (SBs) with defined surface and granulometry were used in the presence of electrolytes (CaCl2) and/or different polymers, including polycarboxylate superplasticizer (PCE) and polyethylene glycol (PEG). It was found the presence of Ca2+ greatly increases the viscosity and yield stress of silica beads paste (SBP), which is proportional to the [Ca2+]. For the effect of PCE, the addition of PCE is beneficial to the flowability of SBP, but a high dosage of PCE leads to a reversal effect. Furthermore, the yield stress firstly increases and then decreases with increasing [Ca2+] under the same dosage of PCE. The addition of PEG always increases the yield stress of SBP, regardless of the ion concentration and the presence or not of PCE. KW - Rheological properties KW - Ions KW - Superplasticizer KW - Silica beads PY - 2019 SN - 978-3-030-22565-0 SN - 978-3-030-22566-7 DO - https://doi.org/10.1007/978-3-030-22566-7_72 SN - 2211-0844 VL - 23 SP - 619 EP - 627 PB - Springer ET - 1 AN - OPUS4-49185 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Steve A1 - Schmidt, Wolfram A1 - Pirskawetz, Stephan A1 - Rogge, Andreas ED - Khayat, Kamal Henry T1 - Fire spalling of self-compacting concrete mixtures with different limestone powder contents N2 - Self-compacting concrete typically contains a higher content of powder materials than normal concrete. Furthermore it is assumed that the use of superplasticizers yields a more homogenous microstructure in the hardened paste. Both aspects generate a very dense microstructure, which can be assumed to cause material behaviour that differs from than normal concrete when it is exposed to elevated temperatures. However, the paste volumes in SCC can vary significantly based on the mixture composition. At a low paste volumes SCC can be very similar to normal concrete at hardened state while it can vary greatly at higher paste volumes. Since the high temperature behaviour of concrete is strongly affected by the different physical behaviour of the paste and the aggregates, it is likely that the high temperature behaviour is consequently strongly affected by the ratio of these mixture components. In the present study different SCC mixtures were observed with similar mechanical properties, but with significantly differing paste to aggregate ratios. Based on observations of the heat evolution at the fire exposed surface and at different depths inside the specimens as well as based on photogrammetric observations of the spalled dimensions, the results indicate that with increasing paste volumes the heat conductivity is reduced and as a result concrete with higher paste to aggregate ratios shows less spalling. T2 - 8th RILEM Symposium on Self-Compacting Concrete CY - Washington, USA DA - 15.05.2016 KW - Spalling KW - High temperature behaviour KW - Fire exposure KW - Mixture composition KW - Photogrammetry PY - 2016 SN - 978-2-35158-157-5 SP - 353 EP - 363 PB - RILEM Publications S.A.R.L. CY - Paris, France AN - OPUS4-36873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Kanjee, J. A1 - Motukwa, G. A1 - Olonade, K. A1 - Dodoo, A. T1 - A snapshot review of future‑oriented standards for cement, admixtures, and concrete: How Africa can spearhead the implementation of green urban construction materials N2 - The existing cement and concrete standards are not capable of making full use of the current technology capacity due to strong focus on conventional concrete and thus they are not fit for the current and future challenges of construction industry. The paper highlights shortcomings with regard to the implementation of the existing standards. It can be seen that future-oriented standards are generally required to contribute to a lower-carbon footprint of the industry. These changes are significantly more relevant in sub-Saharan Africa, due to the rapidly increasing urbanisation challenge and the enormous potentials to develop lower-carbon technologies than elsewhere in the world. KW - Future‑oriented standards KW - Green urban construction KW - Cement PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582563 DO - https://doi.org/10.1557/s43580-023-00563-9 SN - 2731-5894 VL - 4 IS - 8 SP - 557 EP - 565 PB - Springer International Publishing CY - Springer Nature Switzerland, Cham AN - OPUS4-58256 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Z. A1 - Becker, S. A1 - Leinitz, Sarah A1 - Schmidt, Wolfram A1 - von Klitzing, R. A1 - Stephan, D. T1 - Interaction of Different Charged Polymers with Potassium Ions and Their Effect on the Yield Stress of Highly Concentrated Glass Bead Suspensions N2 - The interaction of different charged polymers, namely anionic polycarboxylate superplasticizer (PCE) and neutral polyethylene glycol (PEG) with potassium ions, and their effect on the yield stress of highly concentrated glass bead suspension (GBS), were studied under different concentrations of potassium ions ([K+]). It was found that, compared to the neutral PEG, the negatively charged PCE can be adsorbed on glass beads (GB), and then decreases the yield stress of GBS. The increasing concentration of free polymer in the interstitial liquid phase with the increased polymer dosage leads to the higher yield stress of GBS, which may be caused by the higher Depletion force. In addition, this effect is also related to the charge density of the polymer and the [K+] in the solution. Along with the increase in [K+], the yield stress of GBS increases significantly with the addition of PCE, but this cannot be observed with PEG, which indicates that potassium ions can interact with negatively charged PCE instead of the neutral PEG. At last, the interparticle Forces between two single GB with adsorbed PCE in solutions containing [K+] and PCE were measured by colloidal probe atomic force microscopy to better understand the interaction of the charged polymer with counterions. KW - Yield stress KW - Free polymer KW - Charge density KW - Depletion force KW - Potassium ions PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506015 DO - https://doi.org/10.3390/ma13071490 SN - 1996-1944 VL - 13 IS - 7 SP - 1490, 1 EP - 1490, 16 PB - MDPI AN - OPUS4-50601 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, K. A1 - Mezhov, Alexander A1 - Schmidt, Wolfram T1 - Chemical and thixotropic contribution to the structural build-up of cementitious materials N2 - The structural build-up of fresh cement paste is often considered as a purely thixotropic phenomenon in literature even though cementitious materials undergo a non-reversible hydration process that can have an influence on the structuration process. In the current paper a method is proposed to validate the impact of the non-reversible structural build-up. It is shown that fresh cement paste samples lose their structural gain almost completely due to thixotropy while the structural build-up due to hydration can be observed but occurs in a significantly lower order of magnitude over the course of the first hours of hydration. In addition, it is shown, that the chemical component of the structural build-up accelerates with the onset of the acceleration period of hydration, while its contribution in the entire structural build-up remains constant. KW - Thixotropy KW - Structural build-up KW - Penetration test KW - Rheological properties PY - 2022 DO - https://doi.org/10.1016/j.conbuildmat.2022.128307 SN - 0950-0618 VL - 345 IS - 128307 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-58248 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Radlinska, A. A1 - Nmai, C. A1 - Buregyeya, A. A1 - Lai, W.L. A1 - Kou, S. ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - Why does Africa need African concrete? An observation of concrete in Europe, America, and Asia - and conclusions for Africa N2 - Portland cement, as we know it today, has its origin in Great Britain approximately 170 years ago. Since then, concrete technology has spread out to Europe, the United States, and Japan, where it became a key component for rapid industrial development. Europe, the Unites States and many Asian countries today have developed a high level of technology regarding concrete construction. However, each of them has a unique history and as a result, different “concrete philosophy” depending upon the social, environmental and financial boundary conditions, as well as their evolution throughout the years and local construction traditions. As a result, the word concrete may refer to rather different materials in America, Europe, and Asia. Apart from South Africa, most sub-Saharan African countries cannot look back on a similarly long cement and concrete history. Cement and concrete are rather new materials and not yet well established. This gives African engineers the unique opportunity to learn from past mistakes and to develop a concrete technology, which refers to the best available practice. However, in many sub-Saharan African countries, standards and regulations are adopted (preferably from Europe or the US) without consideration of the historical background of these standards. Although this practice helps saving resources for the implementation, it does not necessarily yield the best result in the African environment, and also from an economic point of view it might come back disadvantageously due to unnecessary overdesigning. By comparing the differing states-of-the-art in North America, Europe, and Asia, this paper emphasizes, how regional conditions determine the practice of concrete technology in the sub-Saharan area. It is therefore important for Africa to develop a unique African concrete technology, which is perfectly fitted to the specific local conditions, even if it may vary distinctively from the established practice elsewhere. The paper concludes that African nations should effort into adapting existing principles that have proved to function well rather than adopting existing standards. T2 - ACCTA - International conference on advances in cement and concrete technology in Africa 2013 CY - Johannesburg, South Africa DA - 28.01.2013 KW - Cement KW - Casting environment KW - Concrete KW - Durability KW - Standards PY - 2013 SN - 978-3-9815360-3-4 SP - 1139 EP - 1147 AN - OPUS4-27767 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pott, U. A1 - Crasselt, Claudia A1 - Fobbe, N. A1 - Haist, M. A1 - Heinemann, M. A1 - Hellmann, S. A1 - Ivanov, D. A1 - Jakob, C. A1 - Jansen, D. A1 - Lei, L. A1 - Li, R. A1 - Link, J. A1 - Lowke, D. A1 - Mechtcherine, V. A1 - Neubauer, J. A1 - Nicia, D. A1 - Plank, J. A1 - Reißig, S. A1 - Schäfer, T. A1 - Schilde, C. A1 - Schmidt, Wolfram A1 - Schröfl, C. A1 - Sowoidnich, T. A1 - Strybny, B. A1 - Ukrainczyk, N. A1 - Wolf, J. A1 - Xiao, P. A1 - Stephan, D. T1 - Characterization data of reference materials used for phase II of the priority program DFG SPP 2005 “Opus Fluidum Futurum –Rheology of reactive, multiscale, multiphase construction materials” N2 - A thorough characterization of base materials is the prereq- uisite for further research. In this paper, the characterization data of the reference materials (CEM I 42.5 R, limestone pow- der, calcined clay and a mixture of these three components) used in the second funding phase of the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented under the aspects of chemical and min- eralogical composition as well as physical and chemical properties. The data were collected based on tests performed by up to eleven research groups involved in this cooperative program. KW - Portland cement KW - Limestone powder KW - Calcined clay KW - Sustainable cement KW - DFG SPP 2005 PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569913 DO - https://doi.org/10.1016/j.dib.2023.108902 VL - 47 SP - 1 EP - 19 PB - Elsevier AN - OPUS4-56991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhang, K. A1 - Mezhov, Alexander A1 - Schmidt, Wolfram T1 - Thixotropic and chemical structural build-up of cement pastes with superplasticizer under different storage conditions N2 - Synopsis: The paper presents the results of a study on the influence of agitation on the structural build-up of fresh cement pastes using a penetration test. It first presents results about the influence of the penetrating shape’s geometry on the influence on the cement paste specimen. Then, results are shown for the load-deflection curves depending upon time and agitation before testing. Based on the observation of the force required to penetrate the sample, conclusions on the structural build-up can be made. The observations were made over the course of time with samples that were left at rest and partly agitated before testing at different time steps. The setup allows to identify the contribution of the chemical reaction to the structural build-up process. The presence of superplasticizer obviously reduces the load that cement paste can withstand, while the loss of thixotropy is found notably lower than that of neat cement pates T2 - 13th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Milan, Italy DA - 10.07.2022 KW - Thixotropy KW - Superplasticizer KW - Structural build-up KW - Texture analyzer KW - Penetration test PY - 2022 DO - https://doi.org/10.14359/51736058 VL - 354 SP - 13 EP - 24 PB - ACI Special Publications AN - OPUS4-58324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhang, K. A1 - Schmidt, Wolfram A1 - Mezhov, Alexander T1 - Influence of the hydroxypropylation of starch on its performance as viscosity modifying agent N2 - Synopsis: Starch is a commonly used viscosity modifying agent (VMA). The performance of starch as VMA depends on its origin (e.g. potato, corn, cassava, etc.) and corresponding molecular properties, such as molecular weight, ratio between amylose and amylopectin etc. Depending upon the application, the efficiency of starch can be enhanced by hydroxypropylation. The maximum degree of substitution (DoS) cannot be greater than 3.0, which is the number of hydroxy groups per glucose monomer in the polymer. In the current research three potato starches exhibiting the DoS of 0.4, 0.6 and 0.8 were utilised. The influence of the modified starch on the rheological properties and hydration of cement paste, as well as the viscosity of the pore solution were investigated. Our findings show that the starch with the highest DoS increases the dynamic yield stress the most, while the plastic viscosity is less dependent on the DoS. Additionally, starch with the highest DoS retards hydration to lower degree than other starches. T2 - 13th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Milan, Italy DA - 10.07.2022 KW - Potato starch KW - Rheological KW - Cement hydration KW - Pore solutions PY - 2022 DO - https://doi.org/10.14359/51736074 VL - 354 SP - 209 EP - 218 PB - ACI Special Publications AN - OPUS4-58320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mezhov, Alexander A1 - Schmidt, Wolfram A1 - Zhang, H. A1 - Diesendruck, Ch. E. T1 - The effect of the charge density of a comb polyphosphate superplasticizer on the structural build-up of cement paste N2 - Synopsis: Lately, there has been rising attention to superplasticizers (SP) based on polyphosphate esters. However, the influence of the molecular structure of the polyphosphate polymers on time-dependent properties such as structural build-up has not been examined yet intensively. To investigate this effect, three comb polyphosphate superplasticizers with different charge densities were synthesised by free radical polymerisation. Our findings indicate that SP with the lowest and medium charge densities extend the induction period more strongly than the SP with the highest charge density. The reduction of the structural build-up rate is linearly dependent on the dosage and concentration of the functional group of polyphosphate SP in the cementitious system. This study proposes a mathematical equation expressing the relationship between the structural build-up rate during the induction period and the molecular structure of the polyphosphate SP. T2 - 13th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Milan, Italien DA - 10.07.2022 KW - Admixture KW - Superplasticizer KW - Polyphosphate KW - Structural build-up PY - 2022 DO - https://doi.org/10.14359/51736079 VL - 354 SP - 255 EP - 262 PB - ACI Special Publications AN - OPUS4-58321 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezhov, Alexander A1 - Zhang, K. A1 - Schmidt, Wolfram T1 - Interactions of Biobased Rheology Modifying Agents with Superplasticizer in Cement Paste N2 - Organic admixtures are an indispensable component of modern concrete. Thus, their purposeful application is not only technically and economically viable but in addition an inevitable tool to make concrete more environmentally friendly. In this context, the use of polysaccharides has increasingly gained interest in the built environment as sustainable resource for performance enhancement. However, due to its origin, biopolymers possess a vast variety of molecular structures which can result in incompatibilities with other polymers present in concrete, such as superplasticizers. The present study highlights effects of the joint application of different types of starches and polycarboxylates with respect to their influence on cement hydration and structural build-up of cement pastes. KW - Polysaccharides KW - Superplasticizers KW - Hydration KW - Cement PY - 2022 DO - https://doi.org/10.4028/www.scientific.net/CTA.1.563 SN - 2674-1237 SP - 563 EP - 568 PB - Trans Tech Publications Ltd, Switzerland CY - Basel, Switzerland. AN - OPUS4-58325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Carvello, J. M. F. A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Fiorotti Peixoto, R. A. T1 - Influence of high-charge and low-charge PCE-based superplasticizers on Portland cement pastes containing particle-size designed recycled mineral admixtures N2 - Design : and use of engineered recycled mineral admixtures obtained from industrial and mineral waste are promising strategies to increase the range of materials suitable for use in cement-based composites. In this work, Portland cement-blended pastes containing mineral admixtures designed for improving particle packing were evaluated in the presence of low- and high-charge polycarboxylate-based superplasticizers. The powders were obtained from basic oxygen furnace slag, iron ore tailings, quartz mining tailings, and quartzite mining tailings. The zeta-potentials of the particles were obtained via electrophoretic mobility. The flow properties were evaluated by rheological tests performed in a Couette type rheometer. The hydration kinetics was evaluated by isothermal calorimetry and an adapted method based on the Vicat needle test. The high-charge PCE and the finer mineral admixtures produced more stable blends. Coarser mineral admixtures led to increased flowability and delayed hydration compared to finer ones. Steel slag powders presented the most significant plasticizer effects, but also the largest setting delays and segregation tendency. Quartz-rich superfines reduced the setting delays caused by the superplasticizers. In summary, both superplasticizers were effective in improving flow properties, but the high-charge PCE was effective in preventing segregation in pastes containing mineral admixtures coarser and heavier than cement. KW - Engineered recycled mineral admixtures KW - Rheology KW - PCE-Based superplasticizer KW - Steel slag KW - Mining tailing PY - 2020 DO - https://doi.org/10.1016/j.jobe.2020.101515 VL - 32 SP - 1 EP - 16 PB - Elsevier AN - OPUS4-58395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Govin, A. A1 - Schmidt, Wolfram A1 - Bartholin, M. C. A1 - Grosseau, P. ED - Amziane, Sofiane ED - Sonebi, M. T1 - Effect of Guar Gum Derivatives Combined with Superplasticizers on Properties of Portland Cement-Pastes N2 - Chemical admixtures allow to the create a variety of fresh and hardened state properties in cementitious materials. In the case of self-compacting concrete, plasticizers or superplasticizers are introduced with the aim to decrease the yield stress and the viscosity of the materials. However, in order to prevent segregation and bleeding, and to improve the water retention of cement-based system, stabilizing agents or viscosity agents are often introduced in addition. Among these admixtures, polysaccharides are most commonly used. The aim of this study is to provide an understanding of competitive or synergetic effects induced by the combination of hydroxypropyl guar stabilizing agents (HPG) and superplasticizers on cement pastes. Two polycarboxylate superplasticizers (PCE) exhibiting different charge densities and one HPG were studied. It was found that the combination of HPG with PCE superplasticizer strongly affects the rheological behavior of cement pastes. Despite the presence of HPG, the viscosity of the pastes strongly decreased with increasing dosage of PCE until it became close to the viscosity of a cement paste with PCE only. However, the use of HPG in combination with PCE allows maintaining a significant yield stress in the cement paste compared to PCE alone. The increase in the charge density of the PCE seemed to amplify the drop of the viscosity and to reduce the gain on the yield stress induced by HPG. The results also highlight a delay in the setting-time of the cement paste by adding HPG and PCE. The delay induced by HPG is significantly lower than that generated by PCEs. However, the combination of the both kind of admixtures leads to a slightly shorter setting-time compared to the PCE alone. T2 - 2nd International Conference on Bio-based Building Materials & 1st Conference on ECOlogical valorisation of GRAnular and FIbrous materials CY - Clermont-Ferrand, France DA - 21.06.2017 KW - Guar gum KW - Polysaccharides KW - Superplasticizer KW - Cement KW - Rheology PY - 2017 VL - PRO 119 SP - 55 EP - 61 PB - RILEM Publications S.A.R.L. CY - Paris AN - OPUS4-41038 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cunningham, Patrick A1 - Schmidt, Wolfram T1 - Cement and clinker imports: embodied carbon, carbon costs, and the EU Carbon Border Adjustment Mechanism (CBAM) N2 - When the European Union (EU) Carbon Border Adjustment Mechanism (CBAM) comes into force, importers of Portland cement and clinker will be required to purchase carbon allowances for their goods. Herein, the trade flows into the EU are mapped by country and the equivalent carbon dioxide (CO2-eq) emissions from production is modeled. Using average allowance prices, the additional cost passed to the consumer if carbon allowances had been purchased for imports in the modeled years are estimated. Together, this retrospective analysis provides insights into CBAM and the potential implications of carbon allowances on the cost of imported goods. KW - Carbon border adjustment mechanism KW - Carbon allowances KW - Cost of carbon KW - Cement KW - Impact shifting PY - 2025 UR - https://www.zkg.de/en/artikel/cement-and-clinker-imports-embodied-carbon-carbon-costs-and-the-eu-carbon-border-adjustment-mechanism-cbam-4252088.html SN - 2748-8330 VL - 78 IS - 3 SP - 54 EP - 58 PB - Bauverlag BV GmbH CY - Gutersloh, Germany AN - OPUS4-63333 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Barthel, Maria A1 - Kühne, Hans-Carsten A1 - Schmidt, Wolfram ED - Bager, D. H. ED - Silfwerbrand, J. T1 - Multilayer concrete pavers - solutions for the mitigation of the urban heat island effect N2 - The large scale application of self-cooling concrete pavers is a future-oriented approach to reduce the urban heat island effect in inner-city areas. Making use of evaporation enthalpy, these new pavements counterbalance the absorption of solar radiation and the subsequent transfer of heat to the surrounding environment. The concrete pavers consist of a permeable top-layer and a storage layer. As the different requirements of these layers demand different concrete mixtures they are developed and optimised for their respective functions. This paper presents some results of the concrete mixture design and Solutions that combine a sufficient compressive strength as well as good water transportation properties for the face concrete layer. T2 - fib Symposium Stockholm 2012 'Concrete structures for a sustainable community' CY - Stockholm, Sweden DA - 11.06.2012 KW - Urban heat island effect KW - Concrete multilayer pavers KW - Permeability KW - Fibre concrete PY - 2012 SN - 978-91-980098-1-1 SP - 513 EP - 516 PB - Royal Institute of Technology CY - Stockholm AN - OPUS4-27271 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Eine einfache experimentelle Methode zur qualitativen Bewertung des Einflusses beliebiger Polycarboxylatether-Fließmittel auf die Rheologie/A rapid experimental method to qualitatively assess the influence of arbitrary polycarboxylate ether superplasticizers on the rheology T2 - 22. Kolloquium und Workshop "Rheologische Messungen an mineralischen Baustoffen" CY - Regensburg, Germany DA - 2013-03-06 PY - 2013 AN - OPUS4-29919 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram T1 - Controlling the mix - Rheology is critical to optimising cement-based compositions N2 - Since the 1980s the range of additives available to modify the behaviour and performance of concrete has greatly expanded. For many applications, control of concrete rheology is critical to obtaining the best performance. The impact of different concrete admixtures on rheology and other factors affecting their selection are discussed. PY - 2015 SN - 0930-3847 IS - 5 SP - 24 EP - 28 PB - Vincentz CY - Hannover AN - OPUS4-33679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Robustness improvement of early age properties of SCC by optimised adjustment of mixture composition and admixtures T2 - International Workshop on Self-Compacting Concrete CY - Belfast, Northern Ireland DA - 2011-04-19 PY - 2011 AN - OPUS4-23715 LA - deu 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 - Zum Einfluss der Menge und Modifikation des Fließmittels auf das Erstarren, die Wärmeentwicklung und die frühen Verformungen von Bindemittelleimen N2 - Es wurden Bindemittelleime aus Zement, Kalksteinmehl, Stabilisierer und Wasser mit Polycarboxylatether-Fließmitteln (PCE) unterschiedlicher Ladungsdichte modifiziert. Die Mischungen wurden in einem automatischen Vicat-Gerät, einem isothermen Wärmeflusskalorimeter sowie mit zwei Schwindkegeln bei Temperaturen von 5, 20 und 30 °C analysiert. Begleitend wurden XRD Messungen durchgeführt. Die Ergebnisse zeigen, dass bei Verwendung von PCE das Erstarrungsende unabhängig von der Temperatur oder der PCE-Modifikation sehr gut mit dem Wendepunkt der Wärmeflusskurve korreliert. Eine derartige Korrelation kann nicht für den Erstarrungsbeginn beobachtet werden. Im Wesentlichen bestimmt die Menge an Polymeren im Gesamtsystem unabhängig von der Struktur eines PCEs den zeitlichen Verlauf des Erstarrens. Der zeitliche Verlauf der frühen Verformungen wird weder von der Menge noch von der Art des Fließmittels signifikant beeinflusst. Aufgrund des starken Einflusses der PCE-Menge auf das Erstarren, kann folglich durch geeignete Fließmittelauswahl das Erstarren gezielt an die Verformungen angepasst werden, so dass signifikante Verformungen überwiegend in einem noch plastischen Zustand stattfinden können. T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 12.09.2012 KW - Polycarboxylatether KW - Fließmittel KW - Erstarren KW - Hydratationswärme KW - Schwinden PY - 2012 SN - 978-3-00-034075-8 VL - 2 IS - 3.07 SP - 2-0392 EP - 2-0399 AN - OPUS4-26543 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Olonade, K. A. A1 - Mbugua, R. N. A1 - Lenz, F. J. A1 - Tchetgnia Ngassam, I. T1 - Bio-Based Rheology Modifiers for High Performance Concrete – Possible Modes of Actions and Case Study for Cassava Starch in West Africa N2 - Polymers that help tailoring rheological properties during the casting process have become inevitable constituents for all kinds of high-performance concrete technologies. Due to lacking industries, these typically crude-oil based admixtures are not readily available in many parts of the world, which limits the implementation of more sustainable high-performance construction technologies in these regions. Alternative polymers, which often demand for less processing, can be derived from local plant-based resources. The paper provides experimental data of flow tests of cement pastes with polysaccharides from Triumfetta pendrata A. Rich, acacia gum and cassava without and in the presence of polycarboxylate ether superplasticizer. The flow tests are amended by observations of the zeta potentials and the hydrodynamic diameters in the presence of and without calcium ions in the dispersion medium. The results show that in the presence of and without calcium ions all polysaccharides provide negative zeta potentials, yet, they affect flowability and thixotropy in different ways. Cassava starch, acacia gum, and the gum of Triumfetta pendrata A. Rich qualified well for robustness improvement, strong stiffening, and additive manufacturing, respectively. The reason for the different effects can be found in their average sizes and size distribution. Due to the promising results, a flow chart for local value chains is derived on the example of yet unused cassava wastes, which can be converted in parallel. T2 - 3rd International Conference on the Application of Superabsorbent Polymers CY - Skukuza, South Africa KW - Admixtures KW - Polysaccharides KW - Rheology KW - Thixotropy KW - Concrete PY - 2020 SN - 978-3-030-33341-6 SN - 978-3-030-33342-3 DO - https://doi.org/10.1007/978-3-030-33342-3_17 SP - 158 EP - 166 PB - Springer AN - OPUS4-58404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Robens-Radermacher, Annika A1 - Unger, Jörg F. A1 - Mezhov, Alexander A1 - Schmidt, Wolfram ED - Biondini, F. ED - Frangopo, D. M. T1 - Temperature dependent modelling approach for early age behavior of printable mortars N2 - Structural build-up describes the stability and early-age strength development of fresh mortar used in 3D printing. lt is influenced by several factors, i.e. the composition of the print­ able material, the printing regime, and the ambient conditions. The existing modelling approaches for structural build-up usually define the model parameters for a specific material composition with­ out considering the influence of the ambient conditions. The goal of this contribution is to explicitly include the temperature dependency in the modelling approach. Temperature changes have signifi­ cant impact on the structural build-up process: an increase of the temperature leads to a faster dissol­ ution of cement phases and accelerates hydration. The proposed extended model includes temperature dependency using the Arrhenius theory. The new model parameters are successfully calibrated based on Viskomat measurement data using Bayesian inference. Furthermore, a higher impact of the temperature in the re-flocculation as in the structuration stage is observed. T2 - The Eighth International Symposium on Life-Cycle Civil Engineering (IALCCE 2023) CY - Milano, Italien DA - 02.07.2023 KW - 3D concrete printing KW - Material characterization KW - Structural build-up KW - Thixotropy KW - Model calibration PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582175 SN - 978-1-003-32302-0 DO - https://doi.org/10.1201/9781003323020-146 SN - 978-1-003-32302-0 VL - 1st Edition SP - 1193 EP - 1200 PB - CRC Press AN - OPUS4-58217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ramirez Caro, Alejandra A1 - Pauli, Jutta A1 - Mota, Berta A1 - Simon, Sebastian A1 - Schmidt, Wolfram A1 - Resch-Genger, Ute T1 - C⁠3A passivation with gypsum and hemihydrate monitored by optical spectroscopy N2 - Tricalcium aluminate (C⁠3A) is found with less than 10% wt. of the total composition; however, during hydration, C⁠3A plays an important role in the early hydration of cement in the presence of gypsum as a set retarder. The aim of this investigation is to assess the suitability of optical spectroscopy and a dye-based optical probe to monitor early hydration of C⁠3A in the presence of gypsum and hemihydrate. Optical evaluation was performed using steady-state fluorescence and diffuses reflectance spectroscopy (UV-VisDR). Phase characterization during hydration was done with in-situ X-ray diffraction. UV-VisDR with a cyanine dye probe was used to monitor the formation of metastable phases and was employed together with fluorescence spectroscopy, to follow the Aggregation and disaggregation of the dye during hydration. In conclusion, for the first time, a cyanine dye was identified as a feasible and stable probe to monitor C⁠3A hydration changes in the presence of calcium sulfate. KW - Dye KW - Photoluminescence KW - Fluorescence KW - Reflection spectroscopy KW - Cement KW - Hydration KW - Method development PY - 2020 DO - https://doi.org/10.1016/j.cemconres.2020.106082 VL - 133 SP - 106082 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-50952 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Controlling Rheology - The Key to Individual Concrete Performance Specifikations T2 - European Coatings Conference "Facade coatings and plasters" CY - Düsseldorf, Germany DA - 2013-10-29 PY - 2013 AN - OPUS4-29921 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Tchetgnia Ngassam, Ines Leana A1 - Olonade, K. A. A1 - Mbugua, R. A1 - Kühne, Hans-Carsten T1 - Plant based chemical admixtures – potentials and effects on the performance of cementitious materials N2 - While today, engineers can choose from a wide range of rheology modifying admixtures, in some parts of the world, these are difficult to access, due to their complex processing. However, alternatives can be bio‐based polymers such as polysaccharides from various sources. These are easily accessible all over the world, do not demand for complicated processing, and typically they are more sustainable than many established materials, which are crude oil‐based. The paper presents the effects of acacia gum, cassava starch and the gum of triumfetta pendrata A. Rich on the rheological performance of cementitious systems. It is shown that acacia gum can be as efficient as polycarboxylate based superplasticisers, cassava starch can reduce the yield stress slightly with little effect on the plastic viscosity, and the gum of triumfet ta pendrata A. Rich increases the thixotropy of cement pastes with plasticizing polymers significantly. KW - Polysaccharides KW - Rheology KW - Cement KW - Chemical admixtures KW - Bio-based concrete PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-476748 DO - https://doi.org/10.21809/rilemtechlett.2018.83 VL - 3 SP - 124 EP - 128 PB - RILEM S.A.R.L. CY - Paris AN - OPUS4-47674 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Tchetgnia Ngassam, Ines A1 - Breitschaft, G. A1 - Virchow, S. ED - Diouri, A. ED - Boukhari, A. ED - Ait Brahim, L. ED - Bahi, L. ED - Khachani, N. ED - Saadi, M. ED - Aride, J. ED - Nounah, A. T1 - Challenges of the growing African cement market – environmental issues, regulative framework, and quality infrastructure requirements N2 - The African cement, concrete and construction business is growing at rapid pace. The cement sales are expected to grow rapidly until 2050. The number of newly built cement plants increases dramatically and in addition more cements are being imported from outside the continent, e.g. from Turkey, Pakistan, Indonesia, and China, driven by overcapacities in the countries of origin. This causes a high number of potentials and challenges at the same time. Newly built cement plants can operate directly at best technological state of the art and thus incorporate more sustainable technologies as well as produce new and more sustainable products such as cements blended with sustainable supplementary cementitious materials such as calcined clays, and industrial or agricultural by products. At the same time the new variety of binding agent as well as the international imports, which are driven by price considerations, make the cement market prone to quality scatter. This puts pressure on the quality control regulations and institutions to ensure safety of construction, healthy application, and environmental safety for the population. The paper presents possible solutions to build up the rapidly increasing African cement production more sustainably than in the rest of the world as well as the related challenges and obstacles that need to be overcome. Based on experiences with a series of pan-African cement testing laboratory proficiency schemes conclusions are made on technical, regulative and political level. T2 - 2nd International Congress on Materials & Structural Stability (CMSS-2017) CY - Rabat, Morocco DA - 22.11.2017 KW - Quality Infrastructure KW - Africa KW - Proficiency Testing KW - Cement KW - Admixtures PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-444330 DO - https://doi.org/10.1051/matecconf/201814901014 SN - 2261-236X VL - 149 SP - 01014-1 EP - 01014-8 PB - EDP Sciences CY - Les Ulis AN - OPUS4-44433 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Leinitz, Sarah ED - Diouri, A. ED - Boukhari, A. ED - Ait Brahim, L. ED - Bahi, L. ED - N., Khachani ED - Saadi, M ED - Aride, J. ED - Nounah, A. T1 - Concrete casting robustness improvement due to active rheology N2 - With ongoing innovation in process technology, the challenges of concrete technology are more and more focused on the rheological optimisation for these processes, since improper mixture stability or poor compaction ability negatively affect the concrete homogeneity and quality. However, along with the increasing complexity of today’s concrete mixture compositions, concrete becomes more prone to failure regarding the casting process. Variable properties of the raw materials typically cause changing workability. The reasons can be found among others in scattering water contents, physical or chemical properties of the cement or varying environmental temperatures. Robustness in the delicately adjusted rheology, however, is of utmost importance for modern and future process technology, from sprayed concrete over pumpable concrete towards 3D-printing, with regard to the long-term strength, the function and the durability. Typically, material induced changes cannot be identified easily due to the complex interactions of concrete constituents. Therefore, a precise and prompt counteraction is impossible. However, it is known that the yield stress can be controlled by addition of supplementary superplasticizer or stabilising agent. In combination with computerized process observation tools that can rapidly interpret and react on changes in the rheology, it is therefore thinkable, that only these two admixture types can adjust the rheology steadily and permanently, regardless of the actual root cause for observed macroscopic rheology change. The presentation will firstly give a comprehensive overview of effects at the interface between pore solution, particles and hydrates, which affect the rheology of fresh concrete. Secondly, ways are recommended how the rheology can be actively manipulated before eventually computerized methods are demonstrated that help to actively and rapidly assess and counteract performance scatter during steady casting processes. T2 - 2nd International Congress on Materials & Structural Stability (CMSS-2017) CY - Rabat, Morocco DA - 22.11.2017 KW - Cusum KW - Rheology KW - Control Chart KW - Concrete KW - Robustness PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-444317 DO - https://doi.org/10.1051/matecconf/201814901001 SN - 2261-236X VL - 149 SP - 01001-1 EP - 01001-7 PB - EDP Sciences CY - Les Ulis AN - OPUS4-44431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Superplasticizer and Shrinkage Reducing Admixture Dosages for Microfine Cement in Grout Systems N2 - Grouts have numerous applications including crack repair as maintenance in construction industries. Microfine cements are intensively used for high strength mortar and grout products. They are ideal for injection grouting in structural repair. Such grouts should have suitable rheological properties to be injectable, especially those used in repair and rehabilitation. The use of superplasticizers (SP) in these products is thus becoming increasingly crucial to achieve favorable workability and viscosity properties. A difficulty in such grouts is the plastic shrinkage due to finer particles used. It is thus necessary to determine optimum SP and shrinkage reducing admixture (SRA) dosages for a microfine cement based grout. In this study, a saturation dosage was decided from two Polycarboxylate ether (PCE) based SPs in relation to neat cement using slump flow and rheological parameters. A range of grout mixtures was formulated containing micro silica (MS) and fly ash (FA), and tested for suitable rheological and mechanical parameters. Based on the results, a grout mixture with MS and FA was selected to determine optimum SRA content. According to the results, a SP dosage of 3% by weight of neat cement is sufficient to achieve saturation. The grout material including MS and FA can produce comparable properties to neat cement grout. MS is found to improve compressive strength within the range considered, whereas a higher FA content provides favourable rheological properties. Finally, a SRA dosage of 4%, which could reduce the shrinkage by about 43% after 28d days, is determined for the grout system. T2 - 2nd International Conference on Building Materials and Materials Engineering (ICBMM 2018) CY - University of Lisbon, Portugal DA - 26.09.2018 KW - Grout KW - Microfine Cement KW - Superplasticizer KW - Supplementary Cementitious Materials KW - Shrinkage Reducing Admixture PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-478319 DO - https://doi.org/10.1051/matecconf/201927801001 VL - 278 SP - Article Number 01001 PB - EDP Sciences AN - OPUS4-47831 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias ED - Alexander, M.G. ED - Beushausen, H. ED - Dehn, F. ED - Moyo, P. T1 - Workability and mechanical properties of ultrafine cement based grout for structural rehabilitation: A parametric study on the partial replacement with SCMs N2 - Grouting is a universal repair and strengthening technique, which is constantly used for structural remediation of concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. Having an extremely small particle size of only few microns, ultrafine cements are ideal for grouting applications due to their superior permeability and compressive strength properties of the hardened cement paste compared to that of the less-expensive, but coarser ordinary Portland cements. Supplementary cementitious materials (SCMs) are often used to replace ultrafine cement in order to modify certain properties and to reduce costs. The aim of this experimental study is to investigate the effect of three supplementary materials: microsilica (MS), fly ash (FA), and metakaolin (MK) on the workability, and mechanical properties of an ultrafine cement based grout with a constant water-binder ratio and constant superplasticizer content. Maximum percentages of replacement with ultrafine cement were 6% by volume of cement for MS and 16% for FA, and MK. In general, results suggest that the workability is improved by addition of FA, whereas is reduced, when modified with MS and MK. The compressive strength of grout after cement replacement remains comparable to that of pure cement grout. However, there is a tendency of the MS to positively affect the compressive strength opposite to FA, whereas flexural strength is positively affected by FA. Based on the results, it is evident that grouts with Hägerman cone flow more than 500 mm and compressive strength of more than 90 MPa after 28 days can be produced. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018) CY - Cape Town, South Africa DA - 19.11.2018 KW - Grouting KW - Repair KW - Box-Behnken KW - Supplementary cementitious materials KW - Analysis of variance PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-464769 DO - https://doi.org/10.1051/matecconf/201819907006 SN - 2261-236X VL - 199 SP - 07006-1 EP - 07006-7 PB - MATEC Web of Conferences AN - OPUS4-46476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pirskawetz, Stephan A1 - Schmidt, Wolfram T1 - Analyse von Schallemissionen bei Zugversuchen an hochduktilem Beton N2 - Hochduktiler Beton eröffnet neue Möglichkeiten bei der Instandsetzung von Bauwerken, der Herstellung dünnwandiger Bauelemente oder dem Einsatz von Dämpfungselementen in stoßartig beanspruchten Bauwerken (z.B. in Erdbebengebieten). Die Steigerung der Duktilität kann durch die Zugabe von Kurzfasern erreicht werden. Im Falle einer Rissbildung in der Zementsteinmatrix überbrücken die Fasern den Riss, nehmen die Spannung vollständig auf und stoppen lokal das Risswachstum. Bei weiterer Steigerung der Last reißt die Matrix an anderer Stelle. Auf diese Weise wird die Rissbildung fein verteilt und es werden große Dehnungen erreicht, bevor das Bauteil versagt. Zur Optimierung der Festbetoneigenschaften müssen die Matrixfestigkeit und die Faserart sowie deren Gehalt aufeinander abgestimmt werden. Dabei sind auch die Verarbeitungseigenschaften des Frischbetons zu berücksichtigen. Anhand der Schallemissionen kann die Rissbildung in der Matrix und die Interaktion mit den Fasern analysiert werden. So konnte in ersten Zugversuchen gezeigt werden, dass sich Schallereignisse dem Versagen der Zementsteinmatrix bzw. dem Auszug der Fasern aus der Matrix zuordnen lassen. Damit steht zur Beurteilung des mechanischen Verhaltens von hochduktilem Beton neben der Spannungs-Dehnungs-Linie ein weiteres Verfahren zur Verfügung. T2 - 20. Kolloquium Schallemission - Statusberichte zur Entwicklung und Anwendung der Schallemissionsanalyse CY - Garmisch-Partenkirchen, Germany DA - 18.06.2015 KW - SHCC KW - Hochduktiler Beton KW - Schallemission KW - Zugversuch KW - PVA-Fasern KW - Faserverstärkter Beton PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-331920 SN - 978-3-940283-73-3 IS - DGZfP-BB 153 SP - Vortrag 4, 1 EP - 7 AN - OPUS4-33192 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Potentials for sustainable cement and concrete technologies - Comparison between Africa and Europe N2 - Cement and concrete technologies in Africa provide vast potentials for sustainable future technologies as well as enormous challenges. The main focus of the symposium is to address existing challenges, possible solutions, and future potentials with all participants. This symposium also aims at offering a platform for networking with relevant players in science and industry. T2 - Cement and Concrete Related Issues for the African Market CY - Yaoundé, Cameroon DA - 02.11.2017 KW - Cement KW - Admixtures KW - Rheology KW - Sustainability KW - Environment PY - 2017 AN - OPUS4-43541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Technologische und wirtschaftliche Lösungsansätze für rheologisch optimierte Betone für subsaharische afrikanische Länder T2 - 21. Tagung "Rheologie von Baustoffen" CY - Regensburg, Germany DA - 2012-02-29 PY - 2012 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-25543 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Franco de Carvalho, J. M. A1 - Defàveri, K- A1 - Castro Mendes, J. A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Fiorotti Peixoto, R. A. T1 - Influence of particle size-designed recycled mineral admixtures on the properties of cement-based composites N2 - In this work, engineered recycled mineral admixtures were obtained from four different industrial residues: basic oxygen furnace slag, iron ore tailings, quartz mining tailings and quartzite mining tailings. The grinding performance was evaluated in two different programs and the characterization included chemical and mineralogical composition, particle morphology, and physical properties. Performance evaluations were carried out in blended pastes and mortars, including flow properties, hydration kinetics, soundness, pozzolanic activity, and compressive strength. Coarser-than-cement admixtures allowed better flow performance, greater dimensional stability and more economical production, while finer-thancementn admixtures improved mechanical performance by both filler effect and cementing activity. KW - Engineered recycled mineral admixtures KW - Rheology KW - Hydration kinetics KW - Basic oxygen furnace slag KW - Iron ore tailings KW - Mining tailings PY - 2021 DO - https://doi.org/10.1016/j.conbuildmat.2020.121640 SN - 0950-0618 VL - 272 SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-58255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haist, M. A1 - Link, J. A1 - Nicia, D. A1 - Leinitz, Sarah A1 - Baumert, C. A1 - von Bronk, T. A1 - Cotardo, D. A1 - Eslami Pirharati, M. A1 - Fataei, S. A1 - Garrecht, H. A1 - Gehlen, C. A1 - Hauschildt, I. A1 - Ivanova, I. A1 - Jesinghausen, S. A1 - Klein, C. A1 - Krauss, H.-W. A1 - Lohaus, L. A1 - Lowke, D. A1 - Mazanec, O. A1 - Pawelczyk, S. A1 - Pott, U. A1 - Radebe, N. W. A1 - Riedmiller, J. J. A1 - Schmid, H.-J. A1 - Schmidt, Wolfram A1 - Secrieru, E. A1 - Stephan, D. A1 - Thiedeitz, M. A1 - Wilhelm, M. A1 - Mechtcherine, V. T1 - Interlaboratory study on rheological properties of cement pastes and reference substances: comparability of measurements performed with different rheometers and measurement geometries N2 - This paper presents the results of an interlaboratory study of the rheological properties of cement paste and ultrasound gel as reference substance. The goal was to quantify the comparability and reproducibility of measurements of the Bingham parameters yield stress and plastic viscosity when measured on one specific paste composition and one particular ultrasound gel in different laboratories using different rheometers and measurement geometries. The procedures for both in preparing the cement paste and carrying out the rheological measurements on cement paste and ultrasound gel were carefully defined for all of the study’s participants. Different conversion schemes for comparing the results obtained with the different measurement setups are presented here and critically discussed. The procedure proposed in this paper ensured a reasonable comparability of the results with a coefficient of variation for the yield stress of 27% and for the plastic viscosity of 24%, despite the individual measurement series’ having been performed in different labs with different rheometers and measurement geometries. KW - Rheometry KW - Rheology KW - Interlaboratory test KW - Test setup KW - Testing procedure KW - Cement paste KW - Ultrasound gel PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511220 DO - https://doi.org/10.1617/s11527-020-01477-w SN - 1871-6873 VL - 53 IS - 4 SP - 92 PB - Rilem AN - OPUS4-51122 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 - Baupraxis und Infrastrukturentwicklung im Hinblick auf die Betonindustrie in Ost- und Südafrika N2 - Der Bausektor stellt in Afrika traditionell eine der stabileren Quellen für den Arbeitsmarkt dar. Durch ständige Wechsel in der Politik wurden jedoch in zahlreichen Ländern Einschnitte bei den öffentlichen Investitionen sowie ein Rückgang der Beschäftigtenzahlen im Privatsektor beobachtet. Darüber hinaus konnte eine Verlagerung von offiziell tätigen und registrierten hin zu nicht registrierten Bauunternehmen festgestellt werden. Zahlreiche Bauunternehmen bieten Dienstleistungen an, die sie nicht ständig ausführen oder für die sie sich das erforderliche Gerät leihen müssen. Einer im Jahre 2000 hinsichtlich der Situation in Tansania veröffentlichten Studie zufolge verfügen nur etwa 15 % der Unternehmen, die Betonbauarbeiten anbieten, über einen eigenen Betonmischer. Die auf dem afrikanischen Kontinent angewandten Baupraktiken im Betonbau weichen erheblich voneinander ab. Während Südafrika über eine fortgeschrittene Technologie und eine hoch entwickelte Infrastruktur im Hinblick auf die Zement- und Betonindustrie verfügt, sind Zement und Beton in den ostafrikanischen Ländern, insbesondere in jenen, die in den 90er Jahren des vergangenen Jahrhunderts von schweren Bürgerkriegen erschüttert wurden, kaum verfügbar und zählen keinesfalls zu den in der täglichen Baupraxis verwendeten Baustoffen. Hier wird auf einheimische Baumethoden, bei denen vorwiegend Holz verwendet wird, zurückgegriffen. Dieses wird durch Abholzung gewonnen, was schließlich zur Rodung ganzer Waldgebiete führt. Die ohne entsprechende Planung, Genehmigung und Erschließung errichteten Siedlungen in Südafrika und Kenia veranschaulichen erschreckend, wie einstmals von grüner Vegetation bedeckte Landstriche in künstliche, wüstenartige Landschaften verwandelt wurden. PY - 2011 SN - 1439-7706 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 - OPUS4-25361 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lorenzoni, Renata A1 - Fritsch, Tobias A1 - Kruschwitz, Sabine A1 - Bruno, Giovanni A1 - Schmidt, Wolfram T1 - Mechanical analysis of cement-biochar composites using in-situ X-ray microtomography and digital volume correlation N2 - This study addresses biochar as a potential carbon-sequestering filler in cement and examines its effect on mechanical properties using X-ray computed tomography (XCT) and digital volume correlation (DVC). DVC was reliably used to measure global displacement and has proven to be an effective method for correcting displacement data obtained from mechanical tests conducted without traditional instrumentation, such as extensometer. This made it possible to measure strain and Young’s modulus accurately. The results demonstrate that while 5 vol% biochar replacement had minimal effect on mechanical properties, a 25 vol% biochar replacement caused a 35 % reduction in Young’s modulus and 40 % reduction in the ultimate compressive strength. Additionally, DVC detected strain concentrations and predicted material failure locations even when cracks could not be quantified using XCT alone. Moreover, the study reveals that biochar particles, due to their sharp geometry, increase internal shear strain during uniaxial compression, unlike round phases such as pores. KW - Cementitious materials KW - Biochar KW - Mechanical proprieties KW - In-situ X-ray microtomography KW - Digital volume correlation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638065 DO - https://doi.org/10.1016/j.conbuildmat.2025.142511 SN - 1879-0526 VL - 490 PB - Elsevier Ltd. AN - OPUS4-63806 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Weimann, Christiane A1 - Chaves Weba, Luciana ED - Schmidt, Wolfram ED - Priebe, Nsesheye Susan T1 - Influences of hydration effects on the flow phenomena of concrete with admixtures N2 - Chemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies such as self-compacting concrete. Today, admixture addition has become common practice in concrete technology, but the understanding of their highly complex mode of operation is extremely difficult and demands for understanding of processes within the range between nanometres and centimetres. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamental mechanisms at the interface between particle or hydrate surfaces and the fluid phase at a very early stage of concrete formation, and links these effects to macroscopic flow phenomena. Methods are discussed that appear promising interdisciplinary tools for enhancement of the understanding of the relevant interactions that are responsible for the macroscopic flow of flowable concrete. T2 - 2nd International Conference on Advances in Cement and Concrete Technology in Africa CY - Dar es Salaam, Tanzania DA - 27.01.2016 KW - Cement hydration KW - Polymer adsorption KW - Rheology KW - Superplasticizer KW - Self-compacting concrete PY - 2016 SN - 978-3-9817502-3-2 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. SP - 79 EP - 88 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-36875 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram ED - Schmidt, W. ED - Uzoegbo, H. T1 - Peculiarities of African cement and concrete markets - Challenges and opportunities N2 - The African environment for the construction with concrete differs greatly from the Situation that can be found in Europe, Japan or North America. Europe can look back upon a concrete tradition of more than 150 years. Standardising documents and guidelines exist since more than 100 years, which formed the foundation of modern Standards that are adopted and applied and in many regions of the world. The technological developments in cement production are also strongly influenced by environmental conditions of the Northern hemisphere. In contrast, with the exception of South Africa, in most countries of sub-Saharan Africa, cement production started in the 1950s to 1960s, followed by a period of political and economical disturbances in many countries. As a result, there have not been serious approaches towards customised Solutions for the construction with concrete for the specific boundary conditions of sub-Saharan Africa. In most countries Standards from overseas are applied. Today, most African economies are growing at a rapid pace and construction activities in infrastructure and housing are urgently required to support and keep up the economic verve. Concrete technology will become of major interest in this context, since no other material can be produced similarly efficiently based on raw materials, which can be found largely only locally. In order to produce concrete with high efficiency, the local boundary framework has to be taken into account. Sub-Saharan Africa exhibits special peculiarities that are not covered by the recently applied technological guidelines and Standards. These need to be addressed to in local codes of practice in order to maximise the benefit of concrete technology. T2 - Bauma Africa 2013 - Global issues in concrete construction - Markets, perspectives, technologies CY - Johannesburg, South Africa DA - 18.09.2013 PY - 2013 SP - 25 EP - 28 AN - OPUS4-30032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Toutlemonde, F. ED - et al., T1 - Performance and interactions of admixtures for SCC exposed to different climatic conditions T2 - Fifth International Conference on Concrete under Severe Conditions: Environment and Loading (CONSEC `07) CY - Tours, France DA - 2007-06-04 PY - 2007 SN - 1628-4704 VL - 2 SP - 979 EP - 986 CY - Tours, France AN - OPUS4-15050 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Tchetgnia Ngassam, I. L. A1 - Mbugua, R. A1 - Olonade, K. A. ED - Greim, M. ED - Kusterle, W. ED - Teubert, O. T1 - Natural rheology modifying admixtures for concrete N2 - The possibility to tailor the rheology of concrete eventually opened up the path to new technologies, where design criteria are no longer limited to the compressive strength. Thus, it can be concluded that the capability to control the rheology of concrete can be considered as catalyst for many of today’s concrete innovations. In the same way rheology modifying admixtures will be key to mastering the challenges of the next decades. In many regions of the Southern hemisphere, the effective use of chemical admixtures would significantly contribute to solve problems induced by the challenging climate, but particularly in Africa there is often a lack of local supply and supply infrastructure. In Africa, concrete admixtures are largely shipped or transported from outside the continent. The long distance transportation of chemicals is not very environmentally friendly and the economic consequences are dramatic: the agents are difficult to purchase, expensive, and there is no large variety of products available in the market. Due to the enormous relevance of rheology modifying admixtures, it is worthwhile to recollect that nature provides an enormous variety of chemicals that can be used readily or with low processing and without enormous transportation distances, since these plants are typically regionally abundantly available, cheap, and they are environmental friendly. The paper presents an overview of various options for rheology modifying admixtures, that can be found in Africa, and that may become a real alternative, once their interaction within the complex cementitious system is well understood. T2 - 26. Workshop und Kolloquium "Rheologische Messungen an Baustoffen" CY - Regensburg, Germany DA - 21.02.2017 KW - Concrete KW - Rheology PY - 2017 SN - 978-3-7439-0171-1 SP - 75 EP - 87 PB - tredition GmbH CY - Hamburg AN - OPUS4-40599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dayani, Shahabeddin A1 - Markötter, Henning A1 - Krug von Nidda, Jonas A1 - Schmidt, Anita A1 - Bruno, Giovanni T1 - Quantification of the Deep Discharge Induced Asymmetric Copper Deposition in Lithium‐Ion Cells by Operando Synchrotron X‐Ray Tomography N2 - AbstractLithium‐ion cells connected in series are prone to an electrical safety risk called overdischarge. This paper presents a comprehensive investigation of the overdischarge phenomenon in lithium‐ion cells using operando nondestructive imaging. The study focuses on understanding the behavior of copper dissolution and deposition during overdischarge, which can lead to irreversible capacity loss and internal short‐circuits. By utilizing synchrotron X‐ray computed tomography (SXCT), the concentration of dissolved and deposited copper per surface area is quantified as a function of depth of discharge, confirming previous findings. The results also highlight for the first time a nonuniform distribution pattern for copper deposition on the cathode. This research provides insights for safer battery cell design. KW - Lithium Ion Batteries KW - Deep Discharge KW - Computer Tomography KW - Copper Deposition KW - Litium Ion Cells PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592717 DO - https://doi.org/10.1002/admt.202301246 SP - 1 EP - 7 PB - Wiley AN - OPUS4-59271 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Nils A1 - Dayani, Shahabeddin A1 - Markötter, Henning A1 - Bau, Alexander A1 - Setzchen, Max A1 - Schmidt, Anita A1 - Kowal, Julia A1 - Krug von Nidda, Jonas T1 - High Precision Nail‐Penetration Setup for the Controlled Thermal Runaway Initiation of Lithium‐Ion Cells at Very Low Temperatures N2 - A high precision nail‐penetration (NP) tool for characterizing the mechanically induced thermal‐runaway (TR) of lithium‐ion battery (LIB) cells in a defined range of temperatures down to −140 °C was developed. To understand the cell specific behavior at low temperatures aiming at the determination of safe handling conditions, different scenarios are analyzed. First, accuracy tests of the NP‐tool regarding motion and penetration depth are conducted with cylindrical cells at different temperatures. Thus, postmortem computer tomographic (CT) images are compared to the data measured with the newly integrated 3‐axis force sensor which is further combined with a high‐resolution position sensor. The herein developed setup allows evaluation of the NP‐metrics at an accuracy of ±1 pierced electrode layer without CT‐scans. Further NP examinations at 20 °C of fully charged cylindrical lithium nickel manganese cobalt oxide cells reveal a reproducible minimum damage as a reliable TR‐trigger. Moreover, NP‐tests at low temperature disclose a relation of the short circuit conductivity and TR‐reactions during subsequent rethermalization to room temperature. Finally, the implementation of a novel fixture for a controlled very fast cooling of LIB‐cells during critical damage opens the way to investigate the individual steps during a TR and, thus, to gain important information of the specific TR‐mechanism of different LIB‐cells. KW - Battery Safety KW - High-precision nail penetration KW - Lithium-ion batteries KW - Abuse testing KW - Thermal runaway PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598127 DO - https://doi.org/10.1002/ente.202301379 SN - 2194-4288 SP - 1 EP - 13 PB - Wiley VHC-Verlag AN - OPUS4-59812 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leonhardt, Robert A1 - Böttcher, Nils A1 - Dayani, Shahabeddin A1 - Rieck, Arielle A1 - Markötter, Henning A1 - Schmidt, Anita A1 - Kowal, Julia A1 - Tichter, Tim A1 - Krug von Nidda, Jonas T1 - Exploring the electrochemical and physical stability of lithium-ion cells exposed to liquid nitrogen N2 - The transport and storage of lithium-ion (Li-ion) batteries — damaged or in an undefined state — is a major safety concern for regulatory institutions, transportation companies, and manufacturers. Since (electro)chemical reactivity is exponentially temperature-dependent, cooling such batteries is an obvious measure for increasing their safety. The present study explores the effect of cryogenic freezing on the electrochemical and physical stability of Li-ion cells. For this purpose, three different types of cells were repeatedly exposed to liquid nitrogen (LN2). Before and after each cooling cycle, electrical and electrochemical measurements were conducted to assess the impact of the individual freezing steps. While the electrochemical behavior of the cells did not change significantly upon exposure to LN2 , it became apparent that a non-negligible number of cells suffered from physical changes (swelling) and functional failures. The latter defect was found to be caused by the current interrupt device of the cylindrical cells. This safety mechanism is triggered by the overpressure of expanding nitrogen which enters the cells at cryogenic temperatures. This study underlines that the widely accepted reversibility of LN2 -cooling on a material scale does not allow for a direct extrapolation toward the physical integrity of full cells. Since nitrogen enters the cell at cryogenic temperatures and expands upon rethermalization, it can cause an internal overpressure. This can, in turn, lead to mechanical damage to the cell. Consequently, a more appropriate temperature condition — less extreme than direct LN2 exposure — needs to be found KW - Lithium-ion battery KW - LN2 cooling KW - Battery characterization PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599248 DO - https://doi.org/10.1016/j.est.2024.111650 VL - 89 SP - 1 EP - 7 PB - Elsevier B.V. AN - OPUS4-59924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Nils A1 - Dayani, Shahabeddin A1 - Markötter, Henning A1 - Schmidt, Anita A1 - Kowal, J. A1 - Lu, Y. A1 - Krug von Nidda, Jonas A1 - Bruno, Giovanni T1 - Visualization of stepwise electrode decomposition in a nail penetrated commercial lithium-ion cell using low-temperature synchrotron X-ray computed tomography N2 - The transition towards zero carbon emissions in power generation hinges on the integration of efficient electrical energy storage systems, with lithium-ion batteries (LIBs) positioned as a pivotal technology. While generally safe, deviations in their operational guidelines due to manufacturing defects or misuse can lead to critical safety concerns, notably thermal runaway (TR) events. Internal short circuits (ISCs) are primary initiators of TR within LIBs. For abuse testing, ISCs are often triggered by nail penetration. This study explores the morphological changes and mechanisms underlying ISC-induced TR in LIBs using operando synchrotron X-ray computed tomography (SXCT) at subzero temperatures. A novel cryogenic setup was developed to control a stepwise temperature increase in the damaged sample while monitoring electrochemical characteristics and simultaneously enabling acquisition of high-resolution SXCT images. The findings reveal that conducting nail penetration at minus 80°C prevents immediate TR, enabling detailed analysis of subsequent structural and electrochemical behavior during controlled thawing. Thus, the initiation of TR processes at localized ISC sites has been observed, evidenced by voltage fluctuations and morphological changes, such as cathode material cracking and decomposition. These results underscore the importance of temperature control in mitigating TR risks and provide critical insights into the internal dynamics of LIBs under abusive conditions. The developed cryogenic SXCT methodology offers a powerful tool for non-destructive, high-resolution investigation of battery failure mechanisms, contributing to the enhancement of LIB safety. KW - Tomography KW - X-ray imaging KW - Lithium-ion battery PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611327 DO - https://doi.org/10.1016/j.jpowsour.2024.235472 VL - 623 SP - 1 EP - 10 PB - Elsevier CY - New York, NY AN - OPUS4-61132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Böttcher, Nils A1 - Sander, Luise A1 - Ulbricht, Alexander A1 - Widjaja, Martinus Putra A1 - Fellinger, Tim-Patrick A1 - Schmidt, Anita A1 - Krug von Nidda, Jonas T1 - Sodium-ion battery research @ BAM (I): investigating the thermal runaway behaviour of commercial sodium-ion battery cells N2 - Commercially available sodium-ion battery (SIB) cells, with energy densities comparable to lithium-ion battery (LIB) cells based on LiFePO4, were investigated regarding their safety behaviour under thermal abuse conditions. Tests were carried out in an inert atmosphere. The SIB-cells went into thermal runaway (TR), intriguingly, even at a rather low state of charge of 30%. The TR-event was coupled with a pronounced jelly roll ejection, challenging the interpretation of the TR-diagrams. These findings highlight the necessity of incorporating SIB-cells into the ongoing safety classification discussions for LIB-cells. KW - Sodium Ion Batteries KW - Thermal Runaway KW - Battery safety PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647652 DO - https://doi.org/10.1039/d5se00687b SN - 2398-4902 VL - 9 IS - 21 SP - 5832 EP - 5838 PB - Royal Society of Chemistry (RSC) AN - OPUS4-64765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Weba, Luciana A1 - Silbernagl, Dorothee A1 - Mota Gassó, Berta A1 - Höhne, Patrick A1 - Sturm, Heinz A1 - Pauli, Jutta A1 - Resch-Genger, Ute A1 - Steinborn, Gabriele ED - Khayat, Kamal Henry T1 - Influences of nano effects on the flow phenomena of self-compacting concrete N2 - Chemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies such as selfcompacting concrete. Meanwhile admixtures have become common practice in concrete technology, but the understanding of these highly complex polymers in the entire concrete system lags far behind their application. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamental mechanisms at the interface between particle or hydrate surfaces and the fluid phase at a very early stage of concrete formation, and links these effects to macroscopic flow phenomena. Methods are discussed that appear promising interdisciplinary tools for enhancement of the understanding of the relevant interactions that are responsible for the macroscopic flow of flowable concrete. T2 - 8th International RILEM Symposium on Self-Compacting Concrete CY - Washington, D.C., USA DA - 15.05.2016 KW - Adsorption KW - Analytics KW - Hydration KW - Polycarboxylate ether KW - Rheology PY - 2016 SP - 245 EP - 254 AN - OPUS4-36882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scharpmann, Philippa A1 - Leonhardt, Robert A1 - Schmidt, Anita A1 - Kowal, Julia A1 - Tichter, Tim A1 - Krug von Nidda, Jonas T1 - Exploring restrictive overdischarge cycling as a method to accelerate characteristic ageing in lithium-ion cells N2 - This study presents a test protocol that greatly accelerates the ageing process of lithium-ion battery cells comprising a positive electrode of nickel manganese cobalt oxide while preserving their characteristic degradation upon cyclic ageing. Applying a repetitive restricted overdischarge, resulting in a depth of discharge larger than 100%, a capacity loss of 20% is achieved over five times faster compared to conventional cycling. The well-known overdischarge degradation phenomenon of copper current collector dissolution is deliberately prevented by setting a discharge cutoff voltage above the theoretical threshold of copper oxidation. Hence, the accelerated degradation can be primarily connected to solid electrolyte interphase growth. A comparative assessment of the ageing dynamics using electrochemical impedance spectroscopy and differential voltage analysis hints towards similar, characteristic degradation processes during accelerated and conventional ageing. A post-ageing examination of the electrical behaviour (i.e., coulombic and energy efficiency, capacity fade) under reference conditions reveals very little to no lasting damages caused by overdischarging. Additionally, post-mortem analysis discloses no increased copper dissolution when comparing cells subjected to accelerated and conventional ageing. Generally, the developed ageing method appears suitable for providing cells with a defined state of health at a reasonable timescale without altering the main degradation mechanisms significantly. KW - Lithium-ion cell KW - Accelerated ageing KW - Overdischarge KW - Degradation processes KW - Differential voltage analysis KW - Electrochemical impedance spectroscopy PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650917 DO - https://doi.org/10.1016/j.jpowsour.2025.239072 SN - 0378-7753 VL - 665 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-65091 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Gluth, Gregor A1 - Florea, M.V.A. A1 - Kumaran, G.S. A1 - Akindahunsi, A. A. A1 - Uzoegbo, H.C. A1 - Oslakovic, I.S. ED - Alexander, M. G. ED - Beushausen, H.-D. ED - Dehn, F. ED - Moyo, P. T1 - Concrete knowledge improvement in sub-Saharan Africa N2 - The building situation in Africa is overwhelmed with high-priced materials and lack of adequate concrete technology, which provides a challenge in the concrete industry. Worldwide, cement and concrete experts are at the cutting-edge to sustainable, green and healthy but nonetheless high-performance concrete, which is more sustainable and safer than traditional methods of construction with clay and wood. Since concrete in Africa is rather a new construction material, this sustainability experience can offer the continent a unique opportunity to begin a constantly growing building sector with the newest state-of-the-art technology. This can be achieved without subordinating to existing standards by establishing a sustainable “African concrete technology”. The major challenge for most sub-Saharan countries is the deficiency of experts, which would be required to establish such state-of-the-art technology. Based on the examples of two African-European scientific networks—SPIN and LightSHIP—this paper presents possible solution strategies for the establishment of a scientific cooperation between Europe and Africa, with links to policy making bodies that can help accelerate the progress of cement and concrete industries in Africa. T2 - 3rd International conference on concrete repair, rehabilitation and retrofitting III CY - Cape Town, South Africa DA - 03.09.2012 KW - Education KW - Research sub-Sahara KW - Africa KW - Cement KW - Concrete PY - 2012 SN - 978-0-415-89952-9 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. IS - Theme 5 SP - 1459 EP - 1465 PB - CRC Press CY - London, UK AN - OPUS4-26508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meinel, M. A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Betontechnologische Ansätze zur Erweiterung der Leistungsmerkmale von Betonpflastersteinen N2 - Die zunehmende Bebauung und Ausweitung städtischer Gebiete führt auf Grund entstehender Wärmespeichermassen zu innerstädtischen Hitzeinseln. Dieses Phänomen ist weithin als „Urban Heat Island Effect“ oder UHI bekannt. Der Einsatz von selbstkühlenden Betonpflastersteinen könnte diesem Phänomen entgegenwirken. Derartige Steine sollen Wasser speichern, wobei dieses bei erhöhten Temperaturen wieder verdunsten soll. Durch die Nutzung der Verdunstungsenthalpie ergibt sich eine Senkung der Oberflächentemperatur. Bei einer großflächigen Verwendung dieser Pflastersteine ist eine Reduzierung der Umgebungstemperatur verglichen mit normalen Bodenbelägen möglich. Durch Sieblinienoptimierung geeigneter Betone soll sich ein guter Kompromiss zwischen erforderlichen mechanischen Eigenschaften sowie guter Transporteigenschaften für Wasser bzw. Wasserdampf ergeben. Als besonders zweckmäßig erweisen sich Mischungen mit gleichen Anteilen an Fein- und Grobkorn. Ein Ansatz zur Realisierung der Wasserspeicherung im Betonpflasterstein stellt der Einsatz von Papierasche, einem Reststoff aus der Papierindustrie, dar. KW - Betonpflastersteine KW - Urban heat island effect PY - 2012 SN - 1439-7706 VL - 2 SP - 94 EP - 100 PB - ad-media-Verl. CY - Köln AN - OPUS4-27117 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bugel, S. A1 - Hahnel, M. A1 - Kunde, T. A1 - de Sousa Amadeu, Nader A1 - Sun, Y. A1 - Spieß, A. A1 - Beglau, T. H. Y. A1 - Janiak, C. A1 - Schmidt, B. M. T1 - Synthesis and Characterization of a Crystalline Imine-Based Covalent Organic Framework with Triazine Node and Biphenyl Linker and Its Fluorinated Derivate for CO2/CH4 Separation N2 - A catalyst-free Schiff base reaction was applied to synthesize two imine-linked covalent organic frameworks (COFs). The condensation reaction of 1,3,5-tris-(4-aminophenyl)triazine (TAPT) with 4,4′-biphenyldicarboxaldehyde led to the structure of HHU-COF-1 (HHU = Heinrich-Heine University). The fluorinated analog HHU-COF-2 was obtained with 2,2′,3,3′,5,5′,6,6′-octafluoro-4,4′-biphenyldicarboxaldehyde. Solid-state NMR, infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis confirmed the successful formation of the two network structures. The crystalline materials are characterized by high Brunauer–Emmett–Teller surface areas of 2352 m2/g for HHU-COF-1 and 1356 m2/g for HHU-COF-2. The products of a larger-scale synthesis were applied to prepare mixed-matrix membranes (MMMs) with the polymer Matrimid. CO2/CH4 permeation tests revealed a moderate increase in CO2 permeability at constant selectivity for HHU-COF-1 as a dispersed phase, whereas application of the fluorinated COF led to a CO2/CH4 selectivity increase from 42 for the pure Matrimid membrane to 51 for 8 wt% of HHU-COF-2 and a permeability increase from 6.8 to 13.0 Barrer for the 24 wt% MMM. KW - MOF KW - Filter PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547632 DO - https://doi.org/10.3390/ma15082807 SN - 1996-1944 VL - 15 IS - 8 SP - 1 EP - 18 PB - MDPI AN - OPUS4-54763 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schmidt, Wolfram A1 - Dauda, Risikat Oladoyin A1 - Reitz, Judith A1 - Misselwitz, Philipp A1 - Bassioni, Ghada A1 - Olonade, Kolawole Adisa A1 - van Damme, Henri A1 - Marangu, Josep Mwiti A1 - Dias Toledo Filho, Romildo A1 - Stürwald, Simone A1 - Schiewer, Gesine Leonore A1 - Hanein, Theodore A1 - Boru, Zamzam Bonaya A1 - Christensen, Randi A1 - Mack Vergara, Yazmin Lisbeth A1 - Hoelzel, Fabienne A1 - Apollo, Buregyeya A1 - Kyarisiima, Hope A1 - Thiedeitz, Mareike A1 - Suraneni, Prannoy A1 - Lorenz, Werner A1 - Osmani, Mohamed A1 - Lesutis, Gediminas A1 - Hanhausen, Rosa A1 - Lehmann, Steffen A1 - Madundo, Mariam Marco A1 - Bader, Vera Simone A1 - Rashdi, Rabia A1 - Landrou, Gnanli A1 - Hafez, Hisham A1 - Howe, Lindsay A1 - Kamashanju, Kabibi Charles A1 - Mohtashami, Nazanin A1 - Opoku, Richard Addo A1 - Erhahon-Nanna, Aisosa A1 - Mellinghoff, Zanele ED - Schmidt, Wolfram ED - Kamashanju, Kabibi Charles ED - Dauda, Risikat Oladoyin ED - Reitz, Judith ED - Misselwitz, Philipp T1 - Renewable, low-carbon materials and (infra)structures for inclusive and equitable human habitat - A position paper derived from the ReLive Habitat Scoping Workshop in August 2025 at the Xplanatorium in Hannover N2 - In order to create sustainable lifestyles and societies in the long term, sustainability goals must be balanced in terms of the environment, the economy and society. However, these targets are sometimes in conflict with each other and cannot be balanced without compromise. Today, the sustainability debate focuses primarily on balancing environmental/climate and economic targets. Social aspects tend to play a marginal role in the debate. This is also the case in the construction industry, which contributes significantly to global energy consumption and high grey and operational CO2 emissions worldwide. For this reason, research and politics have focused intensively in recent decades on ways to reduce climate emissions while maintaining economic efficiency. Historically, the focus in construction has been on structural safety. The classic credo in engineering was ‘more is more’. In the context of the climate debate, however, ‘less is more’ often applies, so that engineers and architects today face an economic conflict of objectives between the classic requirements for failure probability and the requirements for sustainable, resource-saving construction, which calls for completely new, much more holistic approaches to material development and structural design. The aim here is to build in a way that is both economical and climate-friendly without compromising structural safety, which is already a complex undertaking. However, the influence of the use of materials, architecture and construction technology on social aspects is often given much less consideration in the sustainability debate, even though enormous population growth and urbanisation processes are expected in the future, particularly in developing economic areas. This inevitably requires a stronger focus on the socio-economic aspects of construction, especially since, in contrast to many current metropolises, many conurbations in these regions will emerge in areas that are not yet densely populated. This provides freedom for innovative concepts that avoid the mistakes of the past and can consider all aspects of sustainability as largely equal. This freedom enables construction methods and urban concepts that use renewable, circular, local materials to create adaptable, accessible and liveable structures that are equitable, inclusive and fair for society. This position paper deals with the socio-economic footprint of materials and buildings. It was compiled by an interdisciplinary group of international experts and attempts to develop approaches for effective socio-economic life cycle analysis using similar concepts to those used in environmental life cycle analysis of products and buildings. In contrast to economic analyses or environmental life cycle assessments, which can work with reasonably available and clearly defined units to develop indicators, it is often impossible to determine units for socio-economic indicators, data is more difficult to obtain and there is a lack of benchmarks. During the discussions, a number of relevant parameters were developed, which can provide clearly quantifiable indicators for socio economic effects. These are related to largely available economic and employment data and consider the distribution of project contracts during implementation and the employment figures associated with project implementation. Particularly in the implementation of large-scale projects involving international investors and financial institutions, ‘(green) compliance value extractivism’ effects can occur, whereby partners from the donor countries are given preference over local project partners. This fraction of the loan flow directly abroad and can no longer serve the local economy to grow. This results in economic follow-up costs, even with lower project costs, which can promote social injustices. The higher the proportion of local companies and employees at engineering levels, the more fairly the construction project serves the local economy. T2 - ReLive Habitat-Scoping-Workshop: Renewable, Low-carbon Materials and (Infra-)structures for Inclusive and Equitable Human Habitat CY - Hannover, Germany DA - 13.08.2025 KW - Socio-economic footprint KW - Life cycle analysis KW - Sustainability KW - Urbanisation KW - Low carbon materials KW - Low carbon structures KW - Human habitat KW - Inclusiveness PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654742 DO - https://doi.org/10.26272/opus4-65474 VL - 2026 SP - i EP - 24 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-65474 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hmood, F. A1 - Schmidt, Franziska A1 - Görke, O. A1 - Günster, Jens T1 - Investigation of chemically modified ICIE16 bioactive glass, part II N2 - Chemically modified bioactive glasses based on ICIE16 were prepared with the melt-quenching method using water as a quenching medium. The sinterability of these bioactive glasses was investigated and is discussed in this article. The sintering experiments were conducted with different sintering temperatures, sintering times and heating rates. Those parameters are crucial for dense glass with an amorphous structure. The particle size (d50) of the starting glass powder was determined at 88 μm and kept constant. The pre-pressed glass pellets were cold-isostatically pressed at 300 MPa to a green density of around 63 %. Density development, phase identification, shrinkage behavior and the microstructure were investigated to determine the sinterability of the developed glasses. The glass powders were sintered at different temperatures inside the processing window while crystallization was monitored. The results have shown that the sinterability of the developed glasses strongly dependsonthe proposed chemical additions. The highest density reached was 96 %, which belongs to BP1 glass with sintering conditions of 20 K/min heating rate for 60 min at 750 °C. KW - Bioactive glass KW - Viscous sintering KW - Crystallization KW - Processing window KW - Grain boundary PY - 2019 DO - https://doi.org/10.4416/JCST2019-00031 VL - 11 IS - 1 SP - 1 EP - 9 PB - Göller Verlag AN - OPUS4-49913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Crasselt, Claudia A1 - Schmidt, Wolfram A1 - Sturm, Heinz T1 - Influence of Rheology Modifying Admixtures on Hydration of Cementitious Suspensions N2 - The presence of polycarboxylate ether (PCE) based superplasticizers (SPs) has an enormous influence on the early hydration of cement. The hydration is retarded and the timing of formation and the morphology of hydrates is affected. This short paper presents experimental results about the influence of delayed addition time of PCE SPs on hydration of cement and alite pastes, investigated by isothermal heat flow calorimetry. For cement as well as for alite pastes the hydration is retarded with SP, whereby the high charge PCE has a stronger retarding effect than the low charge PCE. The retardation caused by PCE is much more pronounced for alite than for cement mixes. If PCE is added later to the mix, the induction period is shortened and the hydration is accelerated compared to simultaneous addition. This applies for cement and alite pastes. With delayed PCE addition the alite shows a clearly less retarded setting and main hydration than after simultaneous addition. It is obvious that for alite pastes there is less retardation the later the addition of SP. T2 - 6th International Symposium on Nanotechnology in Construction CY - Hong Kong, China DA - 02.12.2018 KW - Polycarboxylate ether (PCE) KW - Early hydration KW - Cement PY - 2018 SP - 1 EP - 8 AN - OPUS4-47204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Mota Gassó, Berta A1 - Sturm, Heinz A1 - Pauli, Jutta ED - Greim, M. ED - Kusterle, W. ED - Teubert, O. T1 - Influence of effects on nano and micro scale on the rheological performance of cement paste, mortar and concrete N2 - Chemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies such as self-compacting concrete. Today, admixture addition has become common practice in concrete technology, but the understanding of their highly complex mode of operation is extremely difficult and demands for understanding of processes within the range between nanometres and centimetres. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamental mechanisms at the interface between particle or hydrate surfaces and the fluid phase at a very early stage of concrete formation, and links these effects to macroscopic flow phenomena. Methods are discussed that appear promising interdisciplinary tools for enhancement of the understanding of the relevant interactions that are responsible for the macroscopic flow of flowable concrete. T2 - 25. Workshop und Kolloquium Rheologische Messsungen an Baustoffen CY - Regensburg, Germany DA - 02.03.2016 KW - Rheology KW - Cement KW - Concrete KW - Superplasticizer KW - Nano scale PY - 2016 SN - 978-3-7345-1313-8 SP - 294 EP - 307 PB - tredition CY - Hamburg AN - OPUS4-36862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leonhardt, Robert A1 - Krug von Nidda, Jonas A1 - Andrae, Dirk A1 - Schmidt, Anita A1 - Kowal, Julia A1 - Tichter, Tim T1 - Reconstructing the distribution of relaxation times with analytical basis functions N2 - The present work proposes the implementation of non-singular basis functions into the algorithm for reconstructing the distribution of relaxation times (DRT) function of impedance data. These functions reflect the dispersed and asymmetrical nature of non-ideal capacitive–resistive processes. Inclusion is achieved by combining the singular Debye distribution basis with distributed relaxation functions, such as those derived from the analytical models of Cole–Cole and Havriliak–Negami. The shapes of the introduced basis functions are described by constant parameters, for which an empirical optimization approach is provided alongside. Using synthetic impedance data of non-ideal capacitive–resistive processes subjected to white noise, it is shown that the demand for regularization can be reduced significantly by using distributed bases. To underline the practical relevance of non-singular basis functions in DRT reconstruction, an experimental study comprising 100 sodium-ion and 80 lithium-ion ommercial cells is presented. In this context, it is shown that auxiliary information from the non-ideal nature of real-world electrochemical processes is outsourced into the basis and, hence, easily filtered out of the resulting DRT. This facilitates the separation of single processes without post-DRT curve fitting and thus improves the interpretation and classification of impedance data significantly. KW - Electrochemical Impedance Spectroscopy; KW - Distribution of relaxation times KW - Basis function KW - Cole-Cole KW - Cole-Davidson KW - Havriliak-Negami PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635486 DO - https://doi.org/10.1016/j.jpowsour.2025.237403 SN - 0378-7753 VL - 652 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-63548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bügel, Stefanie A1 - Hähnel, Malte A1 - Kunde, Tom A1 - de Sousa Amadeu, Nader A1 - Sun, Yangyang A1 - Spieß, Alex A1 - Beglau, Thi Hai Yen A1 - Schmidt, Bernd M. A1 - Janiak, Christoph T1 - Synthesis and Characterization of a Crystalline Imine-Based Covalent Organic Framework with Triazine Node and Biphenyl Linker and Its Fluorinated Derivate for CO2/CH4 Separation N2 - : A catalyst-free Schiff base reaction was applied to synthesize two imine-linked covalent organic frameworks (COFs). The condensation reaction of 1,3,5-tris-(4-aminophenyl)triazine (TAPT) with 4,40-biphenyldicarboxaldehyde led to the structure of HHU-COF-1 (HHU = Heinrich-Heine University). The fluorinated analog HHU-COF-2 was obtained with 2,20,3,30,5,50,6,60-octafluoro 4,40 -biphenyldicarboxaldehyde. Solid-state NMR, infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis confirmed the successful formation of the two network structures. The crystalline materials are characterized by high Brunauer–Emmett–Teller surface areas of 2352 m2/g for HHU-COF-1 and 1356 m2/g for HHU-COF-2. The products of a larger-scale synthesis were applied to prepare mixed-matrix membranes (MMMs) with the polymer Matrimid. CO2/CH4 permeation tests revealed a moderate increase in CO2 permeability at constant selectivity for HHU-COF-1 as a dispersed phase, whereas application of the fluorinated COF led to a CO2/CH4 selectivity increase from 42 for the pure Matrimid membrane to 51 for 8 wt% of HHU-COF-2 and a permeability increase from 6.8 to 13.0 Barrer for the 24 wt% MMM KW - Separation KW - COF KW - MMM KW - CO2 PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618625 DO - https://doi.org/10.3390/ma15082807 VL - 15 IS - 8 SP - 2807 PB - MDPI AN - OPUS4-61862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kossatz, Philipp A1 - Mezhov, Alexander A1 - Andresen, Elina A1 - Prinz, Carsten A1 - Schmidt, Wolfram A1 - Resch-Genger, Ute T1 - Assessing the Applicability of Lanthanide-Based Upconverting Nanoparticles for Optically Monitoring Cement Hydration and Tagging Building Materials N2 - Chemically stable, lanthanide-based photon upconversion micro- and nanoparticles (UCNPs) with their characteristic multicolor emission bands in the ultraviolet (UV), visible (vis), near-infrared (NIR), and short-wave infrared (SWIR) arepromising optical reporters and barcoding tags. To assess the applicability of UCNPs for the monitoring of early stage cement hydration processes and as authentication tags for cementitious materials, we screened the evolution of the luminescence of Selfmade core-only NaYF4:Yb,Er UCNPs and commercial μm-sized Y2O2S:Yb,Er particles during the first stages of cement hydration, which largely determines the future properties of the hardened material. Parameters explored from the UCNP side included particle size, morphology, surface chemistry or coating, luminescence properties, and concentration in different cement mixtures. From the cement side, the influence of the mineral composition of the cement matrix was representatively examined for ordinary Portland cement (OPC) and its constituents tricalcium aluminate (C3A), tricalcium silicate (C3S), and gypsum at different water to cement ratios. Based on reflection and luminescence measurements, enabling online monitoring, which were complemented by XRD and isothermal heat-flow calorimetric measurements to determine whether the incorporation of these particles could impair cement hydration processes, well suited lanthanide particle reporters could be identified as well as application conditions. In addition, thereby the reporter influence on cement hydration kinetics could be minimized while still preserving a high level of information content. The best performance for the luminescence probing of changes during early stage cement hydration processes was observed for 25 nm-sized oleate (OA)-coated UCNPs added in a concentration of 0.1 wt %. Higher UCNP amounts of 1.0 wt % delayed cement hydration processes size- and surface coatingspecifically in the first 24 h. Subsequent luminescence stability screening studies performed over a period of about one year support the applicability of UCNPs as optical authentication tags for construction materials. KW - Quality assurance KW - Fluorescence KW - Nano KW - Particle KW - Synthesis KW - Quantum yield KW - NIR KW - Mechanism KW - Characterization KW - XRD KW - Calorimetry KW - Advanced material KW - Cement KW - Monitoring KW - Surface KW - Size KW - Lifetime KW - Barcode KW - Lanthanide KW - Upconversion KW - Encoding KW - Method PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638318 DO - https://doi.org/10.1021/acsomega.5c02236 SN - 2470-1343 VL - 10 IS - 29 SP - 31587 EP - 31599 PB - ACS Publications CY - Washington, DC AN - OPUS4-63831 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Antimicrobial resistance in soil microbes mediated by resistance evolution and horizontal gene transfer (HGT) N2 - Question: Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to toxic biocides even though they are not their primary targets. Soil is a large reservoir of microbial diversity and has been hypothesized to be a crucial factor for the evolution and spread of antimicrobial resistance. Currently, there is little knowledge on how biocides used to protect materials affect the evolution and spread of resistance. Thus, our aim is to investigate the risk for the evolution of biocide resistance and cross-resistance to antibiotics. In addition, we aim to elucidate the affect of biocides on the spread of resistance via horizontal gene transfer (HGT). Methods: In laboratory evolution experiments we culture selected model soil microorganism with representative biocides followed by antibiotic cross-resistance determination and genome sequencing. Moreover, we investigate if the selected biocides affect the HGT frequency of plasmids that carry resistance genes among soil microorganism and the consequences for survival of the affected populations. Results: Our initial results show only small increases of biocide resistance during serial transfers in the presence of biocides. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, we will present results from ongoing experiments on the effects of material preservatives on HGT frequencies facilitating microbial community adaptation to stress. Conclusions: The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives. T2 - 8th Congress of European Microbiologists - FEMS 2019 CY - Glasgow, UK DA - 07.07.2019 KW - Biocides KW - Horizontal gene transfer HGT KW - Microbiology KW - Resistance evolution KW - Antimicrobial resistance PY - 2019 AN - OPUS4-49402 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Antimicrobial resistance in soil microbes mediated by resistance evolution and horizontal gene transfer (HGT) N2 - Question: Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to toxic biocides even though they are not their primary targets. Soil is a large reservoir of microbial diversity and has been hypothesized to be a crucial factor for the evolution and spread of antimicrobial resistance. Currently, there is little knowledge on how biocides used to protect materials affect the evolution and spread of resistance. Thus, our aim is to investigate the risk for the evolution of biocide resistance and cross-resistance to antibiotics. In addition, we aim to elucidate the affect of biocides on the spread of resistance via horizontal gene transfer (HGT). Methods: In laboratory evolution experiments we culture selected model soil microorganism with representative biocides followed by antibiotic cross-resistance determination and genome sequencing. Moreover, we investigate if the selected biocides affect the HGT frequency of plasmids that carry resistance genes among soil microorganism and the consequences for survival of the affected populations. Results: Our initial results show only small increases of biocide resistance during serial transfers in the presence of biocides. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, we will present results from ongoing experiments on the effects of material preservatives on HGT frequencies facilitating microbial community adaptation to stress. Conclusions: The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives. T2 - Symposium für Doktorandinnen und Doktoranden – 2019 CY - Berlin, Germany DA - 27.09.2019 KW - Biocides KW - Horizontal gene transfer HGT KW - Microbiology KW - Resistance evolution KW - Antimicrobial resistance PY - 2019 AN - OPUS4-49404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Antimicrobial resistance in soil microbes mediated by resistance evolution and horizontal gene transfer (HGT) N2 - Questions: Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to toxic biocides even though they are not their primary targets. Soil is a large reservoir of microbial diversity and has been hypothesized to be a crucial factor for the evolution and spread of antimicrobial resistance. Currently, there is little knowledge on how biocides used to protect materials affect the evolution and spread of resistance. Thus, our aim is to investigate the risk for the evolution of biocide resistance and cross-resistance to antibiotics. In addition, we aim to elucidate the affect of biocides on the spread of resistance via horizontal gene transfer (HGT). Methods: In laboratory evolution experiments we culture selected model soil microorganism with representative biocides followed by antibiotic cross-resistance determination and genome sequencing. Moreover, we investigate if the selected biocides affect the HGT frequency of plasmids that carry resistance genes among soil microorganism and the consequences for survival of the affected populations. Results: Our initial results show only small increases of biocide resistance during serial transfers in the presence of biocides. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, we will present results from ongoing experiments on the effects of material preservatives on HGT frequencies facilitating microbial community adaptation to stress. Conclusions: The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives. T2 - 5th International Symposium on the Environmental Dimension of Antibiotic Resistance (EDAR) CY - Hong Kong, China DA - 09.06.2019 KW - Biocides KW - Horizontal gene transfer HGT KW - Microbiology KW - Resistance evolution KW - Antimicrobial resistance PY - 2019 AN - OPUS4-49401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Martin T1 - Selbstentzündungsverhalten von Feststoffen: Validierung der Extrapolation von Labortests N2 - In der Regel wird das Selbstentzündungsverhalten mit Hilfe von isoperibolen oder adiabaten Warmlagerungsversuchen beurteilt, hier liegen die Probenvolumina üblicherweise im Bereich von ca. 100 cm3 bis zu einigen Litern. Die Extrapolation auf technisch relevante Volumina birgt jedoch erhebliche Unsicherheiten. Diese beruhen auf: - Extrapolation über mehrere Größenordnungen, - Limitierungen der verwendeten Extrapolationsmethode (enge Start- und Randbedingungen), - dem unterschiedlichen Temperaturniveau der Laborversuche im Vergleich zu technischen Lagerungen, insbesondere der Einfluss des enthaltenen Wassers, - nicht eindeutige Kriterien für Zündung/Nichtzündung, - Einfluss verschiedener Extrapolationsverfahren, - mit Hilfe von Laborversuchen nicht erfassbarer Reaktionen (Niedertemperaturoxidationen, Zersetzung, Autokatalyse etc.), - Streuungen der Messergebnisse. Diese Unsicherheiten zu verringern ist Inhalt des vorgestellten Forschungsprojektes. Hauptziele des Projektes sind daher, die im Labormaßstab vorhandenen Prüfeinrichtungen durch einen Versuchsstand zur Untersuchung von Probengrößen von bis zu 1000 dm3 zu erweitern, die Eignung (oder Nichteignung) der etablierten Methoden nachzuweisen und im Labormaßstab nicht erfassbare Einflussgrößen zu ermitteln. Zudem sollen anhand der kleinskaligen Tests Entscheidungskriterien abgeleitet werden, ob eine Extrapolation nach den derzeit üblichen Methoden zulässig ist. Erste Ergebnisse des Projektes bestätigen, dass die Bestimmung des Selbstentzündungsverhaltens von Stäuben und Schüttgütern und insbesondere die Ermittlung reaktionskinetischer Daten mit erheblichen Unsicherheiten behaftet sind. Sowohl Warmlagefungsversuche im Labormaßstab als auch mit Hilfe verschiedener Methoden ausgewertete thermoanalytische Methoden lassen, insbesondere einzeln betrachtet, zum Teil nur bedingt verlässliche Aussagen über das Selbstentzündungsverhalten großer Schüttungen zu. Vollständige Versuchsreihen unter Nutzung aller vorgestellten Untersuchungsmethoden sollen präsentiert und abhängig vom Probenmaterial - Schlussfolgerungen hinsichtlich der Zulässigkeit der Extrapolationsmethoden diskutiert werden. T2 - 14. Fachtagung Anlagen-, Arbeits- und Umweltsicherheit CY - Köthen, Germany DA - 07.11.2019 KW - Spontanious ignition KW - Self-ignition KW - Minimun ignition temperature KW - Dust layers PY - 2019 AN - OPUS4-50073 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Martin A1 - Wu, D. A1 - Song, Z. A1 - Zhang, Q. A1 - Qian, X. T1 - Theoretical and numerical study on ignition behaviour of coal dust layers on a hot surface with corrected kinetic parameters N2 - Industrial fires and explosions initiating from self-ignition of combustible porous dust deposits represent a serious hazard for human beings, environment and industry. Understanding the fundamental basis of combustible dust ignition behaviours at different geometries is of importance to prevent and mitigate the accidental risks. A correlation of self-ignition temperatures (SITs) measured by hot-oven tests and minimum ignition temperatures of dust layers (MITLs) determined by hot-plate tests has been established previously. However, this analogy approach based on Frank-Kamenetzkii model is limited by ignoring the influence of oxygen diffusion. In this work, an improved method is developed by implementing a correction factor for the pre-exponential factor caused by the boundary geometry. This method is testified by comparing with experimental data, previous analogy method and numerical simulation. Results show that our proposed method performs a better predictability of MITLs and simplicity. The improved analogy method indicates that the different boundary geometries of a dust deposit significantly impact the apparent pre-exponential factor, while have an ignorable influence on the activation energy, which is also verified by numerical investigations. Furthermore, the numerical model with the corrected kinetic parameters provides a satisfactory explanation compared with experimental observations regarding to temperature and concentration evolutions of dust layers. KW - Spontanious ignition KW - Self-ignition KW - Minimum ignition temperature KW - Dust layers PY - 2019 DO - https://doi.org/10.1016/j.jhazmat.2019.01.032 VL - 368 SP - 156 EP - 162 PB - Elsevier AN - OPUS4-47854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Explosionen in Rohrleitungen N2 - Deflagrationssicherungen sind Sicherheitseinrichtungen, die den Durchfluss von brennbaren Gasen und Dämpfen brennbarer Flüssigkeiten ermöglichen, den Flammendurchschlag und weitere Explosionsausbreitung nach der Zündung von explosionsfähigen Gas-/Dampf-Luftgemischen jedoch verhindern sollen. Von besonderer Bedeutung für die Wirksamkeit der Deflagrationsrohrsicherung ist der Einbauort. Diesbezügliche Abweichungen von den normativen Anforderungen, die Grundlage der Prüfung und Zulassung von Deflagrationsrohrsicherungen sind, können zum Versagen der Sicherheitseinrichtung führen. Oft lassen sich allerdings aus betrieblichen bzw. verfahrenstechnischen Gründen der Norm entsprechende Einbaubedingungen nur schwer oder nicht realisieren. Deshalb besteht das Ziel der Untersuchungen eines F&E-Vorhabens mit der Braunschweiger Flammenfilter GmbH darin, einen Beitrag zur Schaffung einer belastbaren Datenbasis zu leisten, um den Einfluss von Rohrleitungsverzweigungen auf deflagrative Gasexplosionen systematisch zu bewerten. T2 - 606. Sitzung der AGS (Arbeitsgemeinschaft Schadenverhütung Berlin/Brandenburg) CY - Feuersozietät Berlin, Germany DA - 27.03.2019 KW - Explosionsschutz KW - Deflagration KW - Flammendurchschlagssicherung PY - 2019 AN - OPUS4-47925 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Entwicklung eines Prüfverfahrens für Detonationsrohrsicherungen N2 - Flammendurchschlagsicherungen sind Armaturen, die das Fortschreiten einer Explosion von einem Anlagenteil in den Anderen verhindern. Diese in Rohren verbauten Armaturen sind durchlässig für das jeweils zu transportierende Produkt, verhindern jedoch den Durchtritt von Flammen. Zum Einsatz kommen Flammendurchschlagsicherungen neben großchemischen Anlagen auch beim Transport von Treibstoffen oder an Tankstellen. Die derzeitige Norm zur Prüfung von Flammendurchschlagsicherungen (DIN EN ISO 16852) basiert nur auf Erkenntnissen aus atmosphärischen Tests. Zur Anwendung von Flammendurchschlagsicherungen bei erhöhten Ausgangsdrücken wird ein Verfahren benötigt, das die sichere und reproduzierbare Baumusterprüfung von Flammendurchschlagsicherungen auf ihre Wirksamkeit gegen Explosionen bei nicht-atmosphärischen Bedingungen erlaubt. Dies wiederum führt zu einer höheren Sicherheit und Verfügbarkeit beim Umgang mit brennbaren Stoffen in der Industrie. T2 - 14. Fachtagung "Anlagen-, Arbeits- und Umweltsicherheit" CY - Köthen, Germany DA - 07.11.2019 KW - Explosionsschutz KW - Detonation KW - Flammendurchschlagsicherung KW - Rohrleitungen PY - 2019 AN - OPUS4-49565 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Dirk A1 - Heidermann, Th. T1 - Untersuchungen zur Belastung von Deflagrationsrohrsicherungen in Rohrleitungsverzweigungen N2 - Im 2. Teil des Artikels zu den Untersuchungen zum Einfluss von Rohrleitungsverzweigungen auf die Wirksam­keit von Deflagrationsrohrsicherungen (s. a. [1]) werden die Ergebnisse der visuellen Beobachtungen des Re­aktionsverlaufes sowie die Belastungen der Flammendurchschlagsicherung (s. Bild 1) bei unterschiedlichen Einbaubedingungen in den Vordergrund gestellt. Gegenübergestellt wird die Belastungssituation der Flam­mensperre in einer geraden und einer verzweigten Rohrleitung. Ausdrücklich wurden Einbaubedingungen gewählt, die nicht Normgerecht [2] sind. Verwendet wurde dafür eine speziell gefertigte Deflagrationsrohrsi­cherung, die eine Beobachtung des Reaktionsverlaufs im Bereich der spiralförmig gewickelten Metallbänder erlaubt. Zusätzlich wurde im geschützten Bereich in der Rohrleitung eine Kamera installiert, die die Belas­tungssituation bei den einzelnen Versuchen dokumentierte. Die Ergebnisse bestätigen sehr eindrucksvoll, dass die Belastungssituation der Deflagrationsrohrsicherung sich in Abhängigkeit von der Konfiguration der Rohrleitung entscheidend ändert. KW - Deflagration KW - Flammendurchschlagsicherung KW - Rohrleitungen PY - 2019 SN - 2191-007 VL - 9 IS - 6 SP - 38 EP - 43 PB - VDI Fachmedien GmbH & Co. KG CY - Düsseldorf AN - OPUS4-48212 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Henning, L. M. A1 - Diaz Cubas, D. A1 - Colmenares, M. G. A1 - Schmidt, J. A1 - Bekheet, M. F. A1 - Pauw, Brian Richard A1 - Gurlo, A. A1 - Simon, U. T1 - High specific surface area ordered mesoporous silica COK-12 with tailored pore size N2 - Ordered mesoporous silica materials such as COK-12, analogous to the well-known SBA-15, are characterized by high surface areas and unique features such as defined pore sizes in the meso-size range and high pore ordering. The aim of this work was to prove the washing step and choice of calcination and aging temperature during the COK-12 synthesis as effective tools in tailoring, markedly improving the specific surface area, pore size, and pore volume. By controlling the aging temperature, the pore size was linearly adjusted between 5.7 and 8.1 nm, while preserving the hexagonal ordering of the pores. The synthesized COK-12 powders possess pore volumes and specific surface areas up to 1.23 cm3 g−1 and 860m2 g−1, respectively, which is markedly higher than what has previously been reported about COK-12. The presented results and the environmentally friendly character of the synthesis will make COK-12 more interesting for future adaption to the industrial processes, for example in catalysis, adsorption, or drug delivery. KW - Ordered mesoporous silica KW - Pore size tailoring KW - High specific surface area KW - SAXS KW - Small angle scattering PY - 2019 DO - https://doi.org/10.1016/j.micromeso.2019.01.050 SN - 1387-1811 VL - 280 SP - 133 EP - 143 PB - Elsevier AN - OPUS4-47378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zemke, F. A1 - Schölch, V. A1 - Bekheet, M.F. A1 - Schmidt, Franziska T1 - Surfactant-assisted sol–gel synthesis of mesoporous bioactive glass microspheres N2 - Spherical mesoporous bioactive glasses in the silicon dioxide (SiO2)-phosphorus pentoxide (P2O5)–calcium oxide (CaO) system with a high specific surface area of up to 300m2/g and a medium pore radius of 4 nm were synthesized by using a simple one-pot surfactant-assisted sol–gel synthesis method followed by calcination at 500–700°C. The authors were able to control the particle properties by varying synthesis parameters to achieve microscale powders with spherical morphology and a particle size of around 5–10 mm by employing one structure-directing agent. Due to a high Calcium oxide content of 33·6mol% and a phosphorus pentoxide content of 4·0mol%, the powder showed very good bioactivity up to 7 d of immersion in simulated Body fluid. The resulting microspheres are promising materials for a variety of life science applications, as further processing – for example, granulation – is unnecessary. Microspheres can be applied as materials for powder-based additive manufacturing or in stable suspensions for drug release, in bone cements or fillers. KW - bioactive KW - biomaterials KW - bone PY - 2019 DO - https://doi.org/10.1680/jnaen.18.00020 SN - 2045-9831 SN - 2045-984X VL - 8 IS - 2 SP - 126 EP - 134 PB - ICE Publishing CY - London AN - OPUS4-50148 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolf, M. E. A1 - Vickery, W. M. A1 - Swift-Ramirez, W. A1 - Arnold, A. M. A1 - Orlando, J. D. A1 - Schmidt, S. J. A1 - Liu, Y. A1 - Er, Jasmin A1 - Schusterbauer, Robert A1 - Ahmed, R. A1 - Nickl, Philip A1 - Radnik, Jörg A1 - Donskyi, Ievgen A1 - Sydlik, S. A. T1 - The Mitsunobu reaction for the gentle covalent attachment of biomolecules to graphene oxide N2 - Graphene oxide (GO) has emerged as a promising biomaterial as it is easily and cheaply synthesized, strong, cytocompatible, osteoinductive, and has a well-characterized aqueous degradation pathway. It is also a great substrate for functionalization with biomolecules such as proteins, peptides, and small molecules that can enhance or add bioactivity. Covalent chemical linkages as opposed to typical noncovalent association methods are preferable so that the biomolecules do not quickly diffuse away or face replacement by other proteins, which is critical in long time scale applications like bone regeneration. However, covalent chemistry tends to carry a drawback of harsh reaction conditions that can damage the structure, conformation, and therefore function of a delicate biomolecule like a protein. Here, the Mitsunobu reaction is introduced as a novel method of covalently attaching proteins to graphene oxide. It features gentle reaction conditions and has the added benefit of utilizing the plentiful basal plane alcohol functionalities on graphene oxide, allowing for high yield protein functionalization. The amino acid Glycine (G), the protein bovine serum albumin (BSA), and the small molecule SVAK-12 are utilized to create the three Mitsunobu Graphene (MG) materials G-MG, BSA-MG, and SVAK-MG that demonstrate the wide applicability of this functionalization method. KW - Graphene oxide KW - Mitsunobu reaction KW - Covalent attachment KW - Bovine serum albumin KW - Macrophage polarization KW - Osteogenesis PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630483 DO - https://doi.org/10.1016/j.carbon.2025.120221 VL - 238 SP - 1 EP - 15 PB - Elsevier Ltd. AN - OPUS4-63048 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 energydispersive 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 30kV using low kV STEM – simultaneously with the Through-the-lens (TTL) SE detector, the Bright Field transmitted and Dark Field transmitted signals. By this method a pixel precise information of the particles 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 - Microscopy Conference 2017 CY - Lausanne, Switzerland DA - 21.08.2017 KW - SEM KW - TEM KW - Nanoparticles PY - 2017 UR - http://www.mc2017.ch/ AN - OPUS4-43890 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hendriks, L. A1 - Ramkorun-Schmidt, Benita A1 - Grundlach-Graham, A. A1 - Koch, J. A1 - Grass, R. N. A1 - Jakubowski, Norbert A1 - Günther, D. T1 - Single-particle ICP-MS with online microdroplet calibration: toward matrix independent nanoparticle sizing N2 - Single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) has become an effective tool for the detection and quantification of inorganic nanoparticles (NPs). While sizing of NPs suspended in water is relatively straightforward by sp-ICP-MS, accurate mass quantification of NPs in complex media, such as consumer products and natural systems still remains a challenge. When NPs are suspended in a complex medium, the matrix may affect the analyte sensitivity and lead to inaccurate NP sizing. Here, we investigate the use of an online microdroplet calibration system to size NPs in a single step. In this setup, microdroplets—which are used as the calibrant to determine elemental sensitivities—and nebulized NP-containing solutions are introduced concurrently into the ICP via a dual-inlet sample introduction system. Because calibrant microdroplets and analyte NPs experience the same plasma conditions, both the microdroplets and the NPs are subjected to the same matrix-related signal enhancement or suppression. In this way, the microdroplet calibration standards are automatically matrix matched with the NP-containing solution. The online microdroplet calibration system is combined with an ICP-TOFMS instrument for simultaneous measurement of multiple elements in microdroplets and NPs. We investigate the ability of online microdroplet calibration to compensate for matrix effects through a series of experiments, in which Ag and Au NPs are measured with variable plasma-sampling positions, varying concentrations of HCl and HNO3, varying concentrations of single element solutions, and high concentrations of a salt matrix, i.e. phosphate buffered saline (PBS). Through these experiments, we demonstrate that the online microdroplet calibration strategy provides a matrix-independent mass quantification of analyte NPs in the presence of several established types of matrix effects, including acid effects, space-charge effects, and ionisation suppression. In results presented here, we focus on the size determination of the NPs. KW - Nanoparticle KW - ICP-MS KW - Calibration PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-477589 DO - https://doi.org/10.1039/c8ja00397a SN - 0267-9477 VL - 34 IS - 4 SP - 716 EP - 728 PB - Royal Society of Chemistry CY - London AN - OPUS4-47758 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Göbel, M. A1 - Kirsch, S. A1 - Schwarze, L: A1 - Schmidt, L. A1 - Scholz, H. A1 - Haußmann, J. A1 - Klages, M. A1 - Scholta, J. A1 - Markötter, Henning A1 - Alrwashdeh, S. A1 - Manke, I. A1 - Müller, Bernd R. T1 - Transient limiting current measurements for characterization of gas diffusion layers N2 - The water management in proton exchange membrane fuel cells (PEMFC) is strongly influenced by the design of the gas diffusion layers (GDL). Limiting current measurements in small-scale cells operating at high stoichiometries are useful to determine the oxygen transport resistance. The oxygen transport resistance increases, once water condenses inside the GDL. In this study a new electrochemical method for voltage loss estimation of GDL induced oxygen transport losses are presented. This new method, referred to as “transient limiting current” (TLC), is compared with the literature method. TLC allows a direct estimation of oxygen transport resistance at an arbitrarily conditioned state. This study also presents a case study of liquid water visualization of a PEM fuel cell with varying GDLs types. With the help of quasi in-situ synchrotron X-ray computed tomography and time resolved radiography measurements we investigate appearance and distribution of liquid water inside the GDLs under limiting current conditions. KW - In-situ characterization of GDLs KW - In-situ synchrotron X-ray computed tomography KW - In-situ synchrotron X-ray radiography KW - BAMline PY - 2018 DO - https://doi.org/10.1016/j.jpowsour.2018.09.003 SN - 0378-7753 SN - 1873-2755 VL - 402 SP - 237 EP - 245 PB - Elsevier B.V. AN - OPUS4-46552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Senoner, Mathias A1 - Maaßdorf, A. A1 - Rooch, Heidemarie A1 - Österle, Werner A1 - Malcher, M. A1 - Schmidt, M. A1 - Kollmer, F. A1 - Paul, D. A1 - Hodoroaba, Vasile-Dan A1 - Rades, Steffi A1 - Unger, Wolfgang T1 - Lateral resolution of nanoscaled images delivered by surface-analytical instruments: application of the BAM-L200 certified reference material and related ISO standards N2 - The certified reference material BAM-L200, a nanoscale stripe pattern for length calibration and specification of lateral resolution, is described. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of AlxGa1–xAs and InxGa1–xAs on a GaAs substrate. The surface of BAM-L200 provides a flat pattern with stripe widths ranging down to 1 nm. Calibration distances, grating periods and stripe widths have been certified by TEM with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface-analytical instruments. The feasibility of the reference material for an analysis of the lateral resolution is demonstrated in detail by evaluation of ToF-SIMS, AES and EDX images. Other applications developed in the community are summarized, too. BAM-L200 fully supports the implementation of the revised International Standard ISO 18516 (in preparation) which is based on knowledge outlined in the Technical Report ISO/TR 19319:2013. KW - AES KW - BAM-L200 KW - CRM KW - EDX KW - Imaging KW - Lateral resolution KW - Sharpness KW - Standardisation KW - STXM KW - ToF-SIMS KW - XPEEM KW - XPS KW - Certified reference material KW - Imaging surface analysis PY - 2015 DO - https://doi.org/10.1007/s00216-014-8135-7 SN - 1618-2642 SN - 1618-2650 VL - 407 IS - 11 SP - 3211 EP - 3217 PB - Springer CY - Berlin AN - OPUS4-33033 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hodoroaba, Vasile-Dan A1 - Rades, Steffi A1 - Salge, T. A1 - Mielke, Johannes A1 - Ortel, Erik A1 - Schmidt, R. T1 - Characterisation of nanoparticles by means of high-resolution SEM/EDS in transmission mode N2 - Advances in scanning electron microscopy (SEM) enable the high-resolution imaging of single nanoparticles (NPs) with sizes well below 10 nm. The SEM analysis in transmission mode (T-SEM) of NPs on thin film supports has many benefits when compared to the analysis of NPs on bulk substrates. The enhanced material (mass – thickness) contrast of the T-SEM imaging mode is well suited for in-depth and, particularly valuable, to very accurate, traceable, lateral dimensional measurements of NPs. Compared to samples prepared on bulk substrates, T-SEM with energy dispersive X-ray spectroscopy (EDS) achieves a drastically improved spatial resolution of the emitted X-rays. The poor signal-to-noise ratio of the X-ray spectra emitted by a single nanoparticle (NP) can be improved by the use of high-sensitivity (high collection solid angle) silicon drift (SDD), energy-dispersive X-ray spectrometers (EDS). The EDS spectral imaging of a single NP with a spatial resolution below 10 nm has become possible. This is demonstrated by means of various examples of nanostructures. Advanced data processing of T-SEM/EDS results sets the stage for the automated classification of NPs by feature analysis. This method combines the detection of morphological structures of interest by image processing of T-SEM micrographs with the chemical classification by EDS. T2 - European Microbeam Analysis Society’s 14th European Workshop on Modern Developments and Applications in Microbeam Analysis (EMAS 2015) CY - Portorož, Slovenia DA - 03.05.2015 KW - High-resolution KW - SEM KW - T-SEM KW - EDX KW - Nanoparticles PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-355628 UR - http://iopscience.iop.org/article/10.1088/1757-899X/109/1/012006 DO - https://doi.org/10.1088/1757-899X/109/1/012006 SN - 1757-899X VL - 109 SP - 012006-1 EP - 012006-12 PB - IOP Publishing Ltd CY - Bristol, UK AN - OPUS4-35562 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Harald A1 - Schmidt, Alexandra A1 - Bachmann, V. A1 - Kämpf, K. A1 - Kuhlbusch, T. A1 - Schwirn, K. A1 - Völker, D. ED - Bosse, H. ED - Buhr, E. ED - Dziomba, T. ED - Hodoroaba, Vasile-Dan ED - Klein, T. ED - Krumrey, M. T1 - OECD Test Guideline on particle size and size distribution of manufactured nanomaterials N2 - The properties of nanomaterials are influenced not only by their chemical composition but also by physical properties (such as size, geometry and crystal structure). For the reliable determination and assessment of behaviour and effects of nanomaterials as well as for the determination of the exposure of humans and environment a comprehensive physical-chemical characterization of nanomaterials is essential. This is an important prerequisite to identify them as nanomaterials and to interpret and compare test results and - in future – to forecast interaction and effects of nanomaterials. In 2006, the OECD launched a sponsorship program for the testing of nanomaterials in which 11 nanomaterials were thoroughly investigated using a variety of methods. The aim of the project was, among other things, to find out where problems occur and where there are gaps in the measurement and test procedures and where are changes required. An important outcome of the sponsorship program was the finding that the OECD Test Guidelines should in several cases be extended to the specific needs in testing of nanomaterials. The existing standardized test methods of the OECD for physical-chemical characterization have not been developed for nanomaterials in particular. A high demand for an extension of the test guidelines was identified. Germany complied with the OECD's request in 2017 and has agreed to extend the “Test Guideline on Particle Size Distribution / Fiber Length and Diameter Distributions Test Guideline” for Manufactured Nanomaterials (MN). UBA commissioned BAM and BAuA with the preparation of the Test Guideline. The aim of the project is the development of a harmonized test protocol for a valid and reproducible determination of particle size and size distribution which is one of the most relevant physical-chemical properties for MNs. Different measuring methods provide different results for the size distribution of the particles. This is caused by the different measuring principles of the methods. Each method measures a specific parameter that ultimately determines particle size. First, the measured quantity differs for each method (Scattered light intensity, 2D image / projection, electric mobility, etc.). Second, the calculated diameters of the MN may differ (Feret Diameter, Area Projection, Mobility Diameter, Aerodynamic Diameter, Hydrodynamic Diameter). Third, a measuring method provides a size distribution which is measured either mass-based, surface-based or number-based. A conversion between the results requires additional parameters and thus possibly increases the measurement error. In addition to the technical differences, the individual parameters are strongly influenced by the structure and material of the nanoparticles. For example, a surface functionalization can lead to very different results in the size distribution. The suitability of measurement methods differs with the material of the MN. As a result, two very different results can be measured for the particle size distribution using two different methods, which are nevertheless both correct. Several large projects in recent years therefore concluded that nanomaterials should be characterized by at least two complementary method. Imaging techniques are regarded as one of these methods for the characterization, the complementary methods are supposed to be statistical methods. The different results for the size distribution of nanomaterials become problematic for the registration of new MN. A comparable and reproducible size distribution is a prerequisite for a standardized registration. In the future, the particle size distribution in the EU will also decide on the classification of a substance as a nanomaterial or as a non-nanomaterial. Especially in borderline cases, a standardized and comparable measurement methodology is therefore essential. T2 - NanoWorkshop 2018: Workshop on Reference Nanomaterials CY - Berlin, Germany DA - 14.05.2018 KW - OECD KW - Guideline KW - Particle size distribution KW - Nano KW - Prüfrichtlinie PY - 2019 SN - 978-3-95606-440-1 DO - https://doi.org/10.7795/110.20190412 SN - 0179-0609 VL - F-61 SP - 125 EP - 132 PB - Physikalisch-Technische Bundesanstalt CY - Braunschweig und Berlin AN - OPUS4-49511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kämpf, K. A1 - Bachmann, V. A1 - Bresch, Harald A1 - Schmidt, Alexandra A1 - Kuhlbusch, T. A1 - Schwirn, K. A1 - Völker, D. ED - Bosse, H. ED - Buhr, E. ED - Dziomba, T. ED - Hodoroaba, Vasile-Dan ED - Klein, T. ED - Krumrey, M. T1 - OECD Test Guideline on particle size and particle size distribution of manufactured nanomaterials: simultaneous measurement of length and diameter of fibers N2 - The new OECD test guideline will address the following four main steps in the determination of the length and width distributions of fibers: sample preparation, image acquisition, data evaluation and uncertainty analysis. As the sample preparation has to be optimized for each material, general quality criteria will be given in the protocol. For full visibility of a fiber the appropriate resolution has to be chosen. In the data evaluation the length and diameter of each fiber will be determined concurrently to allow for application of different regulatory definitions. The quality of the results critically depends on the sample preparation as well as the data evaluation. In this step the classification rules have to be formulated and followed accurately in order to optimize reproducibility of the method. The SOP will be validated in an international round robin test, which is planned for 2018/2019. T2 - NanoWorkshop 2018: Workshop on Reference Nanomaterials CY - Berlin, Germany DA - 14.05.2018 KW - OECD KW - Nano KW - Guideline KW - Particle size distributuion KW - Prüfrichtlinie PY - 2019 SN - 978-3-95606-440-1 DO - https://doi.org/10.7795/110.20190412 SN - 0179-0609 VL - F-61 SP - 302 EP - 302 PB - Physikalisch-Technische Bundesanstalt CY - Braunschweig und Berlin AN - OPUS4-49514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dayani, Shahabeddin A1 - Markötter, Henning A1 - Schmidt, Anita A1 - Widjaja, Martinus Putra A1 - Bruno, Giovanni T1 - Multi-level X-ray computed tomography (XCT) investigations of commercial lithium-ion batteries from cell to particle level N2 - Adopting X-ray computed tomography (XCT) for ex-situ characterization of battery materials has gained interest in the past decade. The main goal of this paper is to demonstrate the effectiveness of several X-ray computer tomography techniques to study commercial batteries. General guidelines are provided to select the most suitable imaging equipment and parameters for investigations of lithium-ion batteries, spanning the length scales from cell to electrode, down to particle level. Relevantly, such parameters would also be suitable for operando experiments. Safety mechanisms and manufacturing inconsistencies at cell level as well as defects and inhomogeneity in cathode and anode is illustrated and quantified. Furthermore, relation of beam energy and sample-detector-distance on contrast retrieved from attenuation and phase shift is inspected using Synchrotron XCT. KW - Non-destructive testing KW - X-ray computed tomography KW - Synchrotron X-ray computed tomography KW - Lithium-ion battery PY - 2023 DO - https://doi.org/10.1016/j.est.2023.107453 SN - 2352-152X VL - 66 SP - 107453 PB - Elsevier Ltd. AN - OPUS4-57512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Choi, Youngeun A1 - Schmidt, Carsten A1 - Tinnefeld, Philip A1 - Bald, Ilko A1 - Roedinger, Stefan T1 - A new reporter design based on DNA origami nanostructures for quantification of short oligonucleotides using microbeads N2 - The DNA origami technique has great potential for the development of brighter and more sensitive reporters for fluorescence based detection schemes such as a microbead-based assay in diagnostic applications. The nanostructures can be programmed to include multiple dye molecules to enhance the measured signal as well as multiple probe strands to increase the binding strength of the target oligonucleotide to these nanostructures. Here we present a proof-of-concept study to quantify short oligonucleotides by developing a novel DNA origami based reporter system, combined with planar microbead assays. Analysis of the assays using the VideoScan digital imaging platform showed DNA origami to be a more suitable reporter candidate for quantification of the target oligonucleotides at lower concentrations than a conventional reporter that consists of one dye molecule attached to a single stranded DNA. Efforts have been made to conduct multiplexed analysis of different targets as well as to enhance fluorescence signals obtained from the reporters. We therefore believe that the quantification of short oligonucleotides that exist in low copy numbers is achieved in a better way with the DNA origami nanostructures as reporters. KW - Origami KW - Nanostructures KW - Microbeads KW - DNA origami KW - Oligonucleotides PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-476443 DO - https://doi.org/10.1038/s41598-019-41136-x SN - 2045-2322 VL - 9 SP - 4769, 1 EP - 8 PB - Nature AN - OPUS4-47644 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hodoroaba, Vasile-Dan A1 - Rades, Steffi A1 - Salge, T. A1 - Mielke, Johannes A1 - Ortel, Erik A1 - Schmidt, R. T1 - Characterisation of nanoparticles by means of high-resolution SEM/EDS N2 - Advances in scanning electron microscopy (SEM) enable the high-resolution imaging of single nanoparticles (NPs) with sizes well below 10 nm. The SEM analysis in transmission mode (T-SEM) of NPs on thin film supports has many benefits when compared to the analysis of NPs on bulk substrates. The enhanced material (mass - thickness) contrast of the T-SEM imaging mode is well suited for in-depth and, particularly valuable, to very accurate, traceable, lateral dimensional measurements of NPs. Compared to samples prepared on bulk substrates, T-SEM with energy dispersive X-ray spectroscopy (EDS) achieves a drastically improved spatial resolution of the emitted X-rays. The poor signal-to-noise ratio of the X-ray spectra emitted by a single nanoparticle (NP) can be improved by the use of high-sensitivity (high collection solid angle) silicon drift (SDD), energy-dispersive X-ray spectrometers (EDS). The EDS spectral imaging of a single NP with a spatial resolution below 10 nm has become possible. This is demonstrated by means of various examples of nanostructures. Advanced data processing of T-SEM/EDS results sets the stage for the automated classification of NPs by feature analysis. This method combines the detection of morphological structures of interest by image processing of T-SEM micrographs with the chemical classification by EDS. T2 - EMAS 2015 - 14th European workshop on modern developments and applications in microbeam analysis CY - Portoroz, Slovenia DA - 03.05.2015 KW - SEM KW - T-SEM KW - EDX KW - Nanoparticles KW - High-resolution PY - 2015 SN - 978-90-8227-691-6 DO - https://doi.org/10.1088/1757-899X/109/1/012006 SP - NUR code:972 - Materials Science, 187-199 AN - OPUS4-33258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bresch, Harald A1 - Hodoroaba, Vasile-Dan A1 - Schmidt, Alexandra A1 - Rasmussen, K. A1 - Rauscher, H. T1 - Counting Small Particles in Electron Microscopy Images — Proposal for Rules and Their Application in Practice N2 - Electron microscopy (EM) is the gold standard for the characterisation of the morphology (size and shape) of nanoparticles. Visual observation of objects under examination is always a necessary first step in the characterisation process. Several questions arise when undertaking to identify and count particles to measure their size and shape distribution. In addition to challenges with the dispersion and identification of the particles, more than one protocol for counting particles is in use. This paper focuses on precise rules for the counting of particles in EM micrographs, as this influences the measurement accuracy of the number of particles, thus implicitly affecting the size values of the counted particles. We review and compare four different, commonly used methods for counting, which we then apply in case studies. The impact of the selected counting rule on the obtained final particle size distribution is highlighted. One main aim of this analysis is to support the application of a specific, well-defined counting approach in accordance with regulatory requirements to contribute to achieving more reliable and reproducible results. It is also useful for the new harmonised measurement procedures for determining the particle size and particle size distribution of nanomaterials. KW - Nano KW - Particle size distribution KW - Nanoparticle KW - Nanomaterial KW - OECD PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551891 DO - https://doi.org/10.3390/nano12132238 SN - 2079-4991 VL - 12 IS - 13 SP - 2238 PB - MDPI CY - Basel AN - OPUS4-55189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schwirn, K. A1 - Völker, D. A1 - Ahtianinen, J. A1 - Schmidt, Alexandra A1 - Bresch, Harald A1 - Kämpf, K. A1 - Bachmann, V. A1 - Kuhlbusch, T. ED - Bosse, H. ED - Buhr, E. ED - Dziomba, T. ED - Hodoroaba, Vasile-Dan ED - Klein, T. ED - Krumrey, M. T1 - OECD Test Guidelines development for chemicals safety assessment of nanomaterials N2 - The OECD test guidelines (TGs) for testing chemicals have been widely used for regulatory purposes all over the world since the establishment of the Mutual Acceptance of Data (MAD) principle in 1984. This MAD principle ensures that, if a chemical is tested under the Good Laboratory Practice (GLP) conditions accordingly to an OECD TG, the data should be accepted in all OECD countries. The TGs have been developed, harmonized, internationally validated (round robin tests) and adopted by OECD countries to be used for the physical-chemical characterisation, fate estimation, and hazard identification for risk assessment of various chemicals. In addition to the TGs, OECD Guidance Documents (GDs) usually provide guidance on how to use TGs and how to interpret the results. These GDs do not have to be fully experimentally validated, and hence they are not under MAD, but they are based on relevant published scientific research. But are the existing TGs and the related GDs applicable and adequate for the regulatory testing of nanomaterials? In general, for nanomaterials it is accepted that most of the "endpoints" or more precisely measurement variables are applicable. However, for some endpoints new or amended TGs are needed. In addition, several GDs are needed to give more precise advice on the test performance in order to gain regulatory relevant data on nanomaterials. T2 - NanoWorkshop 2018: Workshop on Reference Nanomaterials CY - Berlin, Germany DA - 14.05.2018 KW - OECD KW - Nano KW - Guideline KW - Nanomaterials KW - Prüfrichtlinie PY - 2019 SN - 978-3-95606-440-1 DO - https://doi.org/10.7795/110.20190412 SN - 0179-0609 VL - F-61 SP - 279 EP - 279 PB - Physikalisch-Technische Bundesanstalt CY - Braunschweig und Berlin AN - OPUS4-49515 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pellegrino, Francesco A1 - Ortel, Erik A1 - Mielke, Johannes A1 - Schmidt, R. A1 - Maurino, V. A1 - Hodoroaba, Vasile-Dan T1 - Customizing New Titanium Dioxide Nanoparticles with Controlled Particle Size and Shape Distribution: A Feasibility Study Toward Reference Materials for Quality Assurance of Nonspherical Nanoparticle Characterization N2 - An overview is given on the synthesis of TiO2 nanoparticles with well-defined nonspherical shapes (platelet like, bipyramidal, and elongated), with the focus on controlled, reproducible synthesis, as a key requirement for the production of reference materials with homogeneous and stable properties. Particularly with regard to the nanoparticle shapes, there is a high need of certified materials, solely one material of this type being commercially available since a few months (elongated TiO2). Further, measurement approaches with electron microscopy as the golden method to tackle the nanoparticle shape are developed to determine accurately the size and shape distribution for such nonspherical particles. A prerequisite for accurate and easy (i.e., automated) image analysis is the sample preparation, which ideally must ensure a deposition of the nanoparticles from liquid suspension onto a substrate such that the particles do not overlap, are solvent-free, and have a high deposition density. Challenges in the Synthesis of perfectly monodispersed and solvent-free TiO2 nanoparticles of platelet and acicular shapes are highlighted as well as successful measurement approaches on how to extract from 2D projection electron micrographs the most accurate spatial information, that is, true 3D size, for example, of the bipyramidal nanoparticles with different geometrical orientations on a substrate. KW - Nanoparticles KW - Titanium dioxide KW - Reference materials KW - Standardisation KW - Particle size and shape distribution PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538849 DO - https://doi.org/10.1002/adem.202101347 VL - 24 IS - 6 SP - 1 EP - 10 PB - Wiley-VCH AN - OPUS4-53884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Alexandra T1 - OECD test guideline on particle size and size distribution: Comparability of measurement results N2 - OECD-Prüfrichtlinien werden weltweit für regulatorische Zwecke angewandt, da sie eine harmonisierte und über internationale Ringversuche validierte Vorschrift zur Analyse vorgeben. Die bestehende Prüfrichtlinie TG 110 zur Größencharakterisierung von Partikeln und Fasern ist für viele Methoden und Materialklassen nicht geeignet, weswegen es Bedarf an einer Neuentwicklung gibt. Im Fokus der neuen TG steht die reproduzierbare und vergleichbare Anwendung von Methoden zur Bestimmung von Partikelgröße sowie Größenverteilung annährend sphärischer und faserförmiger Nanomaterialien im Bereich 1-1000 nm. Berücksichtigt werden die häufig angewandten Methoden zur Größencharakterisierung mit ihren unterschiedlichen physikalisch-technischen Limitierungen und die Bestimmung unterschiedlicher Durchmesser (hydrodynamischer, Feret…). Weiterhin sind materialspezifische Einflüsse durch die Partikel sowie das Messmedium zu berücksichtigen. Jede der Methoden soll unter Berücksichtigung von ISO-Standards und den materialspezifischen Limitierungen in der neuen Prüfrichtlinie beschrieben und über einen Ringversuch validiert werden. T2 - BAM BfR Workshop CY - Berlin, Germany DA - 21.03.2019 KW - OECD KW - Nanoparticle KW - Particle Size KW - Nano KW - Characterization PY - 2019 AN - OPUS4-47633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Martin T1 - Brand- und Explosionsgefahren beim Umgang mit Metallstäuben N2 - Grundlagen des Brand- und Explosionsschutzes mit Schwerpunkt Metallstäube: - Gefahren - Prinzipien des Explosionschutzes - Ableiten von Schutzmaßnahmen - Bestimmung der Stoffeigenschaften - Umgang mit entsprechenden Datenbanken T2 - DGM Fortbildungsseminar "Metallpulver Erzeugen - Charakterisieren - Anwenden" CY - Universität Bremen, Germany DA - 14.03.2019 KW - Brandschutz KW - Explosionsschutz KW - Sicherheitstechnische Kenngrößen PY - 2019 AN - OPUS4-47948 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Martin A1 - Wu, D. A1 - Berghmans, J. T1 - Spontaneous ignition behaviour of coal dust accumulations: A comparison of extrapolation methods from lab-scale to industrial-scale N2 - Smouldering fires and explosions arising from self-ignition of coal dust deposits represent a serious hazard for human being, environment and industry. It is essential for plant operators to know the conditions (temperature, duration and quantity) at which storage will be safe. In this work, self-ignition behaviour of three bituminous coal dusts in large scales are theoretically studied, based on the experimental data via a standardized hot-basket apparatus. A comprehensive 2-D transient model is developed, using a 2nd-order reaction kinetics considering both coal and oxygen consumptions, to investigate self-ignition parameters of coal dust accumulations. The numerical model shows a less conservative prediction compared with the steady-state methods. The computational self-ignition temperature and ignition delay time show a satisfaction agreement with lab-scale experimental results. In addition, the influences of ambient temperature and moisture content are analysed. The result shows that the moisture content delays the ignition and a small variation of the ambient temperature nearby the critical condition will lead to a large difference of the ignition delay time. KW - Spontanious ignition KW - Self-ignition KW - Extrapolation methods PY - 2019 DO - https://doi.org/10.1016/j.proci.2018.05.140 SN - 1540-7489 VL - 37 IS - 3 SP - 4181 EP - 4191 PB - Elsevier AN - OPUS4-47291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk A1 - T., Heidermann T1 - Ergebnisse der experimentellen Untersuchungen zur Visualisierung der Wirksamkeit von Deflagrationsrohrsicherungen in einer PVC-U Rohrleitung N2 - Deflagrationsrohrsicherungen sind Sicherheitseinrichtungen, die den Durchfluss von brennbaren Gasen und Dämpfen brennbarer Flüssigkeiten ermöglichen, den Flammendurchschlag und eine weitere Explosionsausbreitung nach der Zündung von explosionsfähigen Gas-/Dampf-Luftgemischen jedoch verhindern sollen. Die Einbaubedingungen sind dabei von besonderer Bedeutung für die Wirksamkeit der Deflagrationsrohrsicherungen. Oft lassen sich aus betrieblichen bzw. verfahrenstechnischen Gründen entsprechende Einbaubedingungen nur schwer oder nicht realisieren. So können beispielsweise Rohrleitungsverzweigungen zusätzliche Turbulenzen induzieren und dadurch zu erhöhten Flammenausbreitungsgeschwindigkeiten und Explosionsdrücken und ggf. zum Versagen der Deflagrationsrohrsicherung führen. Neben den „klassischen“ Untersuchungsmethoden dieser Belastungssituationen von Deflagrationsrohrsicherungen, wie die Erfassung des Explosionsdruckes und der Flammenausbreitungsgeschwindigkeiten, werden in diesem Beitrag die Ergebnisse der visuellen Beobachtungen des Reaktionsverlaufes sowie die Belastungen der Flammendurchschlagsicherung bei unterschiedlichen Einbaubedingungen in den Vordergrund gestellt. Gegenübergestellt wird die Belastungssituation der Flammensperre in einer geraden und einer verzweigten Rohrleitung. Verwendet wurde dafür eine speziell gefertigte Deflagrationsrohrsicherung, die eine Beobachtung des Reaktionsverlaufs im Bereich der spiralförmig gewickelten Metallbändern erlaubt. Zusätzlich wurde im geschützten Bereich in der Rohrleitung eine Kamera installiert, die die Belastungssituation bei den einzelnen Versuchen dokumentierte. Die Ergebnisse bestätigen sehr eindrucksvoll, dass die Belastungssituation der Deflagrationsrohrsicherung sich in Abhängigkeit von der Konfiguration der Rohrleitung entscheidend ändert T2 - 15. BAM/PTB-Kolloquium zur chemischen und physikalischen Sicherheitstechnik CY - Brunswick, Germany DA - 21.05.2019 KW - Flammendurchschlagsicherungen KW - Rohrleitungen KW - Deflagrationen PY - 2019 DO - https://doi.org/10.7795/210.20190521A VL - 15. SP - 1 EP - 10 PB - PTB CY - Braunschweig AN - OPUS4-48084 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Dirk T1 - Ergebnisse der experimentellen Untersuchungen zur Visualisierung der Wirksamkeit von Deflagrationsrohrsicherungen in einer PVC-U Rohrleitung N2 - Deflagrationsrohrsicherungen sind Sicherheitseinrichtungen, die den Durchfluss von brennbaren Gasen und Dämpfen brennbarer Flüssigkeiten ermöglichen, den Flammendurchschlag und eine weitere Explosionsausbreitung nach der Zündung von explosionsfähigen Gas-/Dampf-Luftgemischen jedoch verhindern sollen. Die Einbaubedingungen sind dabei von besonderer Bedeutung für die Wirksamkeit der Deflagrationsrohrsicherungen. Oft lassen sich aus betrieblichen bzw. verfahrenstechnischen Gründen entsprechende Einbaubedingungen nur schwer oder nicht realisieren. So können beispielsweise Rohrleitungsverzweigungen zusätzliche Turbulenzen induzieren und dadurch zu erhöhten Flammenausbreitungsgeschwindigkeiten und Explosionsdrücken und ggf. zum Versagen der Deflagrationsrohrsicherung führen. Neben den „klassischen“ Untersuchungsmethoden dieser Belastungssituationen von Deflagrationsrohrsicherungen, wie die Erfassung des Explosionsdruckes und der Flammenausbreitungsgeschwindigkeiten, werden in diesem Beitrag die Ergebnisse der visuellen Beobachtungen des Reaktionsverlaufes sowie die Belastungen der Flammendurchschlagsicherung bei unterschiedlichen Einbaubedingungen in den Vordergrund gestellt. Gegenübergestellt wird die Belastungssituation der Flammensperre in einer geraden und einer verzweigten Rohrleitung. Verwendet wurde dafür eine speziell gefertigte Deflagrationsrohrsicherung, die eine Beobachtung des Reaktionsverlaufs im Bereich der spiralförmig gewickelten Metallbändern erlaubt. Zusätzlich wurde im geschützten Bereich in der Rohrleitung eine Kamera installiert, die die Belastungssituation bei den einzelnen Versuchen dokumentierte. Die Ergebnisse bestätigen sehr eindrucksvoll, dass die Belastungssituation der Deflagrationsrohrsicherung sich in Abhängigkeit von der Konfiguration der Rohrleitung entscheidend ändert. T2 - 15. BAM/PTB-Kolloquium zur chemischen und physikalischen Sicherheitstechnik CY - Brunswick, Germany DA - 21.05.2019 KW - Flammendurchschlagsicherungen KW - Rohrleitungen KW - Deflagrationen PY - 2019 AN - OPUS4-48085 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Anita T1 - Alles über Lithiumbatterien (I) N2 - Der Auftakt der Artikelserie beschäftigt sich mit den neuen Verpackungsvorschriften für defekte Lithiumbatterien, die beim Transport gefährlich reagieren können. Die Antworten auf die wichtigsten Fragestellungen. KW - Gefahrgutverpackungen KW - Lithiumbatterien KW - Gefahrgut KW - ADR PY - 2019 SN - 0016-5808 VL - 2019 IS - 06 SP - 20 EP - 23 PB - Storck Verlag CY - Hamburg AN - OPUS4-50800 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Anita T1 - Aktuelle Forschung - Technik für sichere Gefahrguttransporte N2 - Lithiumbatterien, Tanks und Druckgasflaschen: Ihnen ist gemeinsam, dass Gefahrguttransporte mit Ihnen sicher erfolgen müssen. Um dies zu gewährleisten, führt die BAM verschiedene Untersuchungen und Forschungsvorhaben durch. T2 - 35. Internationale Gefahrgut-Tage Hamburg CY - Hamburg, Germany DA - 17.02.2019 KW - Lithiumbatterien KW - Druckgefäße KW - Gefahrguttransport KW - ADR KW - Sicherheit PY - 2019 AN - OPUS4-50802 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Anita T1 - Aktuelles zur Sicherheit von Lithium-Ionen Akkus - Lagerung, Transporte, Brandschutzkonzepte N2 - Sicherheitskonzepte werden für die verschiedenen Szenarien für Lithiumakkus benötigt: Vor allem für den Bereich der Lagerung gibt es im Moment nur wenige Vorgaben. Im Vortrag werden verschiedene Brandschutzkonzepte vorgestellt. Für die Lagerung werden Empfehlungen ausgesprochen, die teilweise an die Vorgaben der Transportvorschriften anknüpfen. T2 - Forum 2019 zur Schadenverhütung der Arbeitsgemeinschaft Berlin Brandenburg (AGS) und AGBB Berlin e.V. CY - Berlin, Germany DA - 23.10.2019 KW - Lithiumbatterien KW - Brandschutzkonzepte KW - Lagerung KW - Gefahrguttransport PY - 2019 AN - OPUS4-50807 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Anita T1 - Zulassungsregeln für Verpackungen von Lithiumbatterien N2 - Sicherer Transport defekter Batterien im Aufgabenbereich der BAM. T2 - 12. Fachkonferenz Lithiumbatterien CY - Frankfurt a.M., Germany DA - 21.01.2019 KW - Lithiumbatterien KW - ADR KW - Gefahrguttransport PY - 2019 AN - OPUS4-50803 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Anita T1 - New ADR regulations for critical lithium batteries N2 - End of life batteries may be damaged or defective and may cause the risk of dangerous reactions. New ADR regulations allow them nevertheless to be tansported with the specifications of the national competent authority. BAM's approach. T2 - End-of-Life Batteries from Electrified Vehicles CY - Fredrikstad Oslo, Norway DA - 13.06.2019 KW - Dangerous goods KW - Defective Lithium batteries KW - ADR KW - Transport PY - 2019 AN - OPUS4-50801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Martin A1 - Erdt, René A1 - Gödde, M. A1 - Salg, S. A1 - Ittemann, L. T1 - Selbstentzündungsverhalten von Feststoffen: Validierung der Extrapolation von Labortests mit Hilfe halbtechnischer Versuche bis 1 m³ N2 - Vorgestellt wird ein 2018 gestartetes Projekt zur Überprüfung der Extrapolation von im Labormaßstab ermittelten Selbstentzündungstemperaturen auf technisch relevante Volumina. Für die Ermittlung reaktionskinetischer Daten von Feststoffschüttungen stehen eine Reihe von Untersuchungsmethoden zur Verfügung. Dies sind thermische Analysen wie z.B. die differential scanning calorimetry DSC sowie Mikrokalorimetrie zur hochgenauen Messung von Wärmeströmen, bei denen sehr geringe Probenmengen zum Einsatz kommen. In der Regel wird das Selbstentzündungsverhalten jedoch mit Hilfe von isoperibolen oder adiabaten Warmlagerungsversuchen beurteilt, hier liegen die Probenvolumina üblicherweise im Bereich von ca. 100 cm³ bis zu einigen Litern. Die Extrapolation über mehrere Größenordnungen auf technische Volumina birgt Unsicherheiten, da mit Zunahme des Lagervolumens veränderte Start- und Randbedingungen vorliegen können. Zudem besteht die Möglichkeit, dass bei in technischen Lagern vorherrschenden niedrigen Temperaturen Reaktionen ablaufen, die in Standard- Laborversuchen nicht erfasst werden aber einen wesentlichen Einfluss auf das Selbstentzündungsverhalten aufweisen können. Hauptziel des Projektes ist es daher, die im Labormaßstab vorhandenen Prüfeinrichtungen durch einen Versuchsstand zur Untersuchung von Probengrößen von bis zu 1000 dm³ zu erweitern, die Eignung (oder Nichteignung) der etablierten Methoden nachzuweisen und im Labormaßstab nicht erfassbare Einflussgrößen zu ermitteln. Zudem sollen anhand der kleinskaligen Tests Entscheidungskriterien abgeleitet werden, ob eine Extrapolation nach den derzeit üblichen Methoden zulässig ist. T2 - 15. BAM-PTB-Kolloquium zur chemischen und physikalischen Sicherheitstechnik CY - Brunswick, Germany DA - 21.05.2019 KW - Spontanious ignition KW - Self-ignition KW - Minimum ignition temperature KW - Dust layers KW - Große Volumina KW - Explosionsschutz KW - Selbstentzündung KW - DSC PY - 2019 DO - https://doi.org/10.7795/210.20190521B SP - 1 EP - 15 PB - Physikalisch-Technische Bundesanstalt (PTB) AN - OPUS4-48939 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, X. A1 - Schmidt, Franziska A1 - Gurlo, A. T1 - Fabrication of polymer-derived ceramics with hierarchical porosities by freeze casting assisted by thiol-ene click chemistry and HF etching N2 - The freeze casting technique assisted with cryo thiol-ene photopolymerization is successfully employed for the fabrication of macroporous polymer-derived silicon oxycarbide with highly aligned porosity. It is demonstrated that the free radical initiated thiol-ene click reaction effectively cross-linked the vinyl-containing liquid polysiloxanes into infusible thermosets even at low temperatures. Furthermore, mixed solution- and suspension-based freeze casting is employed by adding silica nanopowders. SiOC/SiO2 foams with almost perfect cylindrical shapes are obtained, demonstrating that the presence of nano-SiO2 does not restrict the complete photoinduced cross-linking. The post-pyrolysis HF acid treatments of produced SiOC monoliths yields hierarchical porosities, with SiOC/SiO2 nanocomposites after etching demonstrating the highest specific surface area of 494 m2/g and pore sizes across the macro-, meso- and micropores ranges. The newly developed approach gives a versatile solution for the fabrication of bulk polymer-derived ceramics with controlled porosity. KW - Freeze casting KW - Preceramic polymer KW - Hierarchical porosities KW - Thiol-ene click chemistry KW - Frozen state photopolymerization PY - 2019 DO - https://doi.org/10.1016/j.jeurceramsoc.2019.09.038 SN - 0955-2219 VL - 40 IS - 2 SP - 315 EP - 323 PB - Elsevier AN - OPUS4-49172 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Melzer, Michael A1 - Makarov, D. A1 - Schmidt, O. G. T1 - A review on stretchable magnetic field sensorics N2 - The current establishment of stretchable electronics to form a seamless link between soft or even living materials and the digital world is at the forefront of multidisciplinary research efforts, bridging physics, engineering and materials science. Magnetic functionalities can provide a sense of displacement, orientation or proximity to this novel formulation of electronics. This work reviews the recent development of stretchable magnetic field sensorics relying on the combination of metallic thin films revealing a giant magnetoresistance effect with elastomeric materials. Stretchability of the magnetic nanomembranes is achieved by specific morphologic features (e.g. wrinkles or microcracks), which accommodate the applied tensile deformation while maintaining the electrical and magnetic integrity of the sensor device. The entire development, from the demonstration of the world’s first elastically stretchable magnetic sensor to the realization of a technology platform for robust, ready-to-use elastic magnetosensorics is described. Soft giant magnetoresistive elements exhibiting the same sensing performance as on conventional rigid supports, but with fully strain invariant properties up to 270% stretching have been demonstrated. With their unique mechanical properties, these sensor elements readily conform to ubiquitous objects of arbitrary shapes including the human skin. Stretchable magnetoelectronic sensors can equip soft and epidermal electronic systems with navigation, orientation, motion tracking and touchless control capabilities. A variety of novel technologies, like electronic skins, smart textiles, soft robotics and actuators, active medical implants and soft consumer electronics will benefit from these new magnetic functionalities. KW - Stretchable electronics KW - Giant magnetoresistance KW - Magnetic sensors KW - Magnetic thin films PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-502049 DO - https://doi.org/10.1088/1361-6463/ab52cf SN - 0022-3727 (Druck) SN - 1361-6463 (Web) VL - 53 IS - 8 SP - Paper 083002, 34 PB - IOP Publishing AN - OPUS4-50204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gili, A. A1 - Bischoff, B. A1 - Simon, U. A1 - Schmidt, Franziska A1 - Kober, D. A1 - Görke, O. A1 - Bekheet, M. A1 - Gurlo, A. T1 - Ceria-based dual-phase membranes for high-temperature Carbon dioxide separation: Effect of iron doping and pore generation with MgO template N2 - Dual-phase membranes for high-temperature carbon dioxide Separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement These membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce_(0.8) Sm_(0.2) O_(2-d) (SDC) and Ce_(0.8)Sm_(0.19)Fe_(0.01)O_(2-d) (FSDC) ceramic powders were used to form the skeleton in dual-Phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system. KW - Samarium doped ceria KW - SDC KW - FSDC KW - CO2 separation membranes KW - Scavenging effect of iron KW - Permeability PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488612 DO - https://doi.org/10.3390/membranes9090108 SN - 2077-0375 VL - 9 IS - 9 SP - 108, 1 EP - 15 PB - MDPI AN - OPUS4-48861 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lüth, Peter A1 - Frost, K. A1 - Kurth, Lutz A1 - Malow, Marcus A1 - Schmidt, Martin A1 - Michael-Schulz, Heike A1 - Uhlig, S. A1 - Zakel, S. T1 - CEQAT-DGHS Ringversuchsprogramm für die Chemikaliensicherheit - Schlussfolgerungen N2 - Die Ursachen für Chemikalienunfälle können vielfältig sein. Prävention beginnt bereits im Prüflabor, wenn Chemikalien auf ihre gefährlichen Eigenschaften getestet werden. Dazu sind Prüfmethoden entwickelt und veröffentlicht worden, die heute weltweit Anwendung finden. Auf die Validität der Prüfmethode und richtige Durchführung der Prüfung im Laboratorium müssen sich Sicherheitsfachkräfte, Transporteure oder Händler verlassen können. Anhand der in den letzten 10 Jahren im Rahmen des CEQAT-DGHS von BAM und PTB durchgeführten Ringversuche (RV) wird gezeigt, dass bei allen bisher untersuchten Prüfmethoden ein Verbesserungsbedarf besteht. Die RV müssen daher zunächst auf die Methodenverbesserung und -validierung abzielen und nicht auf Leistungstests. Das Labormanagement und die praktische Durchführung der Prüfung sind in vielen Laboratorien verbesserungsbedürftig. Der Begriff „Erfahrung der Prüfer“ ist kritisch zu sehen: Eine „lange Erfahrung mit vielen Prüfungen“ ist nicht unbedingt ein Garant für richtige Ergebnisse. T2 - 15. BAM-PTB-Kolloquium zur chemischen und physikalischen Sicherheitstechnik CY - Braunschweig, Germany DA - 21.05.2019 KW - Gefahrgut KW - Gefahrstoff KW - Ringversuch KW - Prüfmethode KW - Validierung KW - Qualitätssicherung PY - 2019 UR - https://www.ptb.de/cms/index.php?id=18763 DO - https://doi.org/10.7795/210.20190521M SP - 1 EP - 8 PB - Physikalisch-Technische Bundesanstalt (PTB) CY - Braunschweig AN - OPUS4-49489 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lüth, Peter A1 - Frost, K. A1 - Kurth, Lutz A1 - Malow, Marcus A1 - Schmidt, Martin A1 - Michael-Schulz, Heike A1 - Uhlig, S. A1 - Zakel, S. T1 - CEQAT-DGHS Ringversuchsprogramm für die Chemikaliensicherheit – Entwicklung von Verfahren zur Verifizierung der Prüfapparatur am Beispiel der Prüfmethode UN Test N.5 N2 - Prävention beginnt im Prüflabor, wenn Chemikalien auf ihre gefährlichen Eigenschaften getestet werden. Dazu sind Prüfmethoden entwickelt und veröffentlicht worden, die heute weltweit Anwendung finden. Auf die Validität der Prüfmethode und richtige Durchführung der Prüfung im Laboratorium müssen sich Sicherheitsfachkräfte, Transporteure oder Händler verlassen können. Anhand der in den letzten 10 Jahren im Rahmen des CEQAT-DGHS von BAM und PTB durchgeführten Ringversuche (RV) wird gezeigt, dass bei allen bisher untersuchten Prüfmethoden ein Verbesserungsbedarf besteht. Die RV müssen daher zunächst auf die Methodenverbesserung und -validierung abzielen und nicht auf Leistungstests. Das Labormanagement und die praktische Durchführung der Prüfung sind in vielen Laboratorien verbesserungsbedürftig. Der Begriff „Erfahrung der Prüfer“ ist kritisch zu sehen: Eine „lange Erfahrung mit vielen Prüfungen“ ist nicht unbedingt ein Garant für richtige Ergebnisse. Bei der Prüfung der gefährlichen Eigenschaften von Chemikalien sind Referenzmaterialen auf Grund der Instabilität in der Regel nicht verfügbar. Für Prüflaboratorien sind RV daher eine Alternative bei der Qualitätssicherung. RV sind jedoch aufwendig und können nur in relativ großen Zeitabständen durchgeführt werden. Es sind deshalb Verfahren zur Verifizierung z. B. der in den Laboratorien verwendeten Prüfapparaturen zu entwickeln. Die Entwicklung von Verifizierungsverfahren wird am Bespiel der Prüfmethode UN Test N.5 demonstriert. T2 - 15. BAM-PTB-Kolloquium zur chemischen und physikalischen Sicherheitstechnik CY - Braunschweig, Germany DA - 21.05.2019 KW - Gefahrgut KW - Gefahrstoff KW - Ringversuch KW - Prüfmethode KW - Validierung KW - Qualitätssicherung KW - Verifizierung PY - 2019 UR - https://www.ptb.de/cms/index.php?id=18763 DO - https://doi.org/10.7795/210.20190521E SP - 1 EP - 10 CY - Braunschweig AN - OPUS4-49495 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lüth, Peter A1 - Frost, K. A1 - Kurth, Lutz A1 - Malow, Marcus A1 - Michael-Schulz, Heike A1 - Schmidt, Martin A1 - Schulte, Petra A1 - Uhlig, S. A1 - Zakel, S. T1 - CEQAT-DGHS Interlaboratory Test Programme for Chemical Safety - Need of Test Methods Validation N2 - Safety experts, manufacturers, suppliers, importers, employers or consumers must be able to rely on the validity of safety-related test methods and on correct test results and assessments in the laboratory. Via the eChemPortal lots of data from the REACH registration dossiers are available. However, the quality and correctness of the information remains in the responsibility of the data submitter. Unfortunately, we found more or less appropriate information on physicochemical properties and concluded that more quality or adequacy of any data submitted will be needed. Interlaboratory tests play a decisive role in assessing the reliability of test results. Interlaboratory tests on different test methods have been performed by Bundesanstalt für Materialforschung und –prüfung (BAM) and Physikalisch-Technische Bundesanstalt (PTB) in collaboration with the QuoData GmbH during the last 10 years. Significant differences between the results of the participating laboratories were observed in all interlaboratory tests. The deviations of the test results were not caused only by laboratory faults but also by deficiencies of the test method. In view of the interlaboratory test results the following conclusions can be drawn: • To avoid any discrepancy on classification and labelling of chemicals it should become state of the art to use validated test methods and the results accompanied by the measurement uncertainty. • A need for improvement is demonstrated for all examined test methods. Thus, interlaboratory tests shall initially aim at the development, improvement and validation of the test methods and not on proficiency tests. • The laboratory management and the practical execution of the tests need to be improved in many laboratories. • The term "experience of the examiner" must be seen critically: A "long experience with many tests" is not necessarily a guarantee for correct results. T2 - 16th International Symposium on Loss Prevention and Safety Promotion in the Process Industries and accompanying exhibition. Loss prevention 2019 CY - Delft, The Netherlands DA - 16.06.2019 KW - Dangerous goods KW - Hazardous substances KW - Round robin test KW - Interlaboratory comparison KW - Test method KW - Validation KW - Quality assurance PY - 2019 UR - https://www.aidic.it/cet/19/77/001.pdf SN - 978-88-95608-74-7 DO - https://doi.org/10.3303/CET1977001 SN - 2283-9216 VL - 77 SP - 1 EP - 6 PB - Italian Association of Chemical Engineering AN - OPUS4-49496 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Martin T1 - CEQAT-DGHS Interlaboratory Test Programme for Chemical Safety - Need of Test Methods Validation - N2 - Safety experts, manufacturers, suppliers, importers, employers or consumers must be able to rely on the validity of safety-related test methods and on correct test results and assessments in the laboratory. Via the eChemPortal lots of data from the REACH registration dossiers are available. However, the quality and correctness of the information remains in the responsibility of the data submitter. Unfortunately, we found more or less appropriate information on physicochemical properties and concluded that more quality or adequacy of any data submitted will be needed. Interlaboratory tests play a decisive role in assessing the reliability of test results. Interlaboratory tests on different test methods have been performed by Bundesanstalt für Materialforschung und –prüfung (BAM) and Physikalisch-Technische Bundesanstalt (PTB) in collaboration with the QuoData GmbH during the last 10 years. Significant differences between the results of the participating laboratories were observed in all interlaboratory tests. The deviations of the test results were not caused only by laboratory faults but also by deficiencies of the test method. In view of the interlaboratory test results the following conclusions can be drawn: • To avoid any discrepancy on classification and labelling of chemicals it should become state of the art to use validated test methods and the results accompanied by the measurement uncertainty. • A need for improvement is demonstrated for all examined test methods. Thus, interlaboratory tests shall initially aim at the development, improvement and validation of the test methods and not on proficiency tests. • The laboratory management and the practical execution of the tests need to be improved in many laboratories. • The term "experience of the examiner" must be seen critically: A "long experience with many tests" is not necessarily a guarantee for correct results. T2 - 16th International Symposium on Loss Prevention and Safety Promotion in the Process Industrie CY - Delft, Netherlands DA - 16.06.2019 KW - Gefahrgut KW - Gefahrstoff KW - Ringversuch KW - Validierung KW - Qualitätssicherung KW - Prüfmethode PY - 2019 AN - OPUS4-49568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -