TY - JOUR A1 - Huismann, Sven A1 - Weise, Frank A1 - Meng, Birgit A1 - Schneider, U. T1 - Transient strain of high strength concrete at elevated temperatures and the impact of polypropylene fibers N2 - This paper presents the results of an experimental study on the transient strain of high strength concrete (HSC) under heating up to 750 °C and the impact of polypropylene (PP) fibers. Concerning this topic only few results are available in the literature and systematic investigations are missing. However, basic knowledge is necessary for the understanding of the internal damage processes in the material as well as for heated structures. The transient strain during heating can be separated in two basic components: the free thermal strain and the mechanical strain. They were experimentally determined exemplarily for one HSC. For the determination of the mechanisms of transient strain and particularly the influence of PP fibers different techniques were applied. In this context the monitoring of the microcracking was done for the first time with acoustic emission analysis in combination with ultrasonic measurements. This new approach helps fundamentally to explain the impact of PP fibers on free thermal strain and mechanical strain during heating up. Furthermore weight loss measurements were carried out to characterize the moisture transport. It was shown that the PP fibers cause an acceleration of the moisture transport in the temperature range from 200 to 250 °C which leads to drying shrinkage in opposite direction to the free thermal strain. Hence this paper is a contribution to the general understanding of the impact of PP fibers in HSC at high temperatures and emphasizes the important influence of PP fibers on the thermal and mechanical induced strain of HSC. KW - High strength concrete KW - Polypropylene fibers KW - Elevated temperatures KW - Transient strain KW - Acoustic emission KW - Ultrasound PY - 2012 DO - https://doi.org/10.1617/s11527-011-9798-6 SN - 1359-5997 SN - 1871-6873 VL - 45 IS - 5 SP - 793 EP - 801 PB - Springer CY - Dordrecht AN - OPUS4-26029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Hauer, B. A1 - Pierkes, R. A1 - Schäfer, S. A1 - Seidel, M. A1 - Herbst, Tristan A1 - Rübner, Katrin A1 - Meng, Birgit T1 - Verbundforschungsvorhaben 'Nachhaltig Bauen mit Beton' - Potenziale des Sekundärstoffeinsatzes im Betonbau - Teilprojekt B N2 - Die Nutzung und Weiterverarbeitung von Sekundärstoffen kann in der Baustoffherstellung einen Beitrag zum nachhaltigen Bauen leisten. Im Rahmen des Teilprojekts B wurde die Bewertung dieser Potenziale anhand von Beispielen ausgebaut und verifiziert. Die Basis dieser Bewertungsgrundlage ist die Erfüllung der grundlegenden technischen Anforderungen (ökobilanzielle Indikatoren, vergleichende ökobilanzielle Betrachtung). Im Teilprojekt E geht es um die Freisetzung umweltrelevanter Stoffe aus zementgebundenen Baustoffen. Überprüft werden sollte die Übereinstimmung zwischen Laborergebnissen, Modellierungen und realen Grundwasserkonzentrationen. Es wurden Schlitzwände errichtet, die in den Grundwasserleiter einbinden und umweltrelevante Parameter bestimmt. Grundsätzlich hat sich selbst bei Großbaustellen nur eine geringe Beeinflussung der Grundwasserqualität durch Beton ergeben. KW - Sekundärstoff KW - Zement KW - Beton KW - Nachhaltigkeit KW - Bewertung KW - Recycling KW - Betonbrechsand KW - Müllverbrennungsasche KW - Kesselsand KW - Ökobilanz PY - 2011 SN - 978-3-410-65094-2 SN - 0171-7197 IS - 584 SP - 1 EP - 151 PB - Beuth CY - Berlin AN - OPUS4-25982 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wallau, Wilma A1 - Pirskawetz, Stephan A1 - Voland, K. A1 - Weise, Frank A1 - Meng, Birgit ED - De Schutter, G. ED - De Belie, N. ED - Janssens, A. ED - Van Den Bossche, N. T1 - Online monitoring of the expansion of alkali-silica reaction affected concrete prisms implemented to the accelerated concrete prism test at 60 °C N2 - The accelerated concrete prism test (ACPT-60 °C) facilitates testing of alkali-silica reactivity of aggregates within five months. Manual measurement is usually conducted to determine expansion of test specimen every 28 days. This conventional procedure gives only limited insight to expansion behaviour of ASR-affected prisms. Due to the large time intervals, expansion exceeding the critical value of 0.3 mm/m is likely to be noticed late. Continuous recording resolves this problem and delivers beneficial information on the shape of the expansion curve. Displacement transducers integrated into a special testing equipment developed at BAM put continuous measurement into practice. Additionally, ultrasonic velocity and acoustic emissions are measured in-situ and provide deeper insights into hydration and crack formation processes during the test. Aiming for an automated testing method close to the German guideline, the following technical and methodical challenges arise. Changing of the vertical orientation of the prisms with every manual measurement as standardised cannot be implemented. Furthermore, preliminary results already proved true that cooling and heating cycles, as necessarily associated with each manual measurement, can evoke additional expansion. Therefore, interrupted and continuously measured expansions reveal systematic differences, indicating the necessity to adjust the threshold expansion value for automated testing. Results presented in the paper: Different types of reactive aggregate have been tested applying continuous and manual expansion measurement to the concrete specimens. Development of continuously measured ultrasonic velocity and acoustic emissions of the aggregates tested diverge significantly while the expansion curves vary in shape and maximum strain. Prisms produced from a slowly reacting aggregate do not exhibit noticeable crack formation. It shows that comprehensive measuring helps describing and distinguishing ASR-damage mechanisms. Models of ASR-induced expansion, available in the open literature, so far are validated with discontinuous data hardly tracing the modelled curve. Continuous measurement improves validation and further model development. T2 - XIV DBMC - 14th International Conference on Durability of Building Materials and Components CY - Gent, Belgium DA - 29.05.2017 KW - Alkali-silica reaction KW - Accelerated concrete prism test KW - Continuous monitoring KW - Expansion modelling PY - 2017 SN - 978-2-35158-159-9 VL - PRO 107 SP - 1 EP - 11 PB - RILEM Publications S.A.R.L. AN - OPUS4-40499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Birgit T1 - Wissensbasierte Digitalisierung von betontechnologischen Materialdaten N2 - Die sprunghaft zunehmende Wichtigkeit von FAIR- und Open-Data für die Qualitätssicherung, aber auch für die Nachnutzbarkeit von Daten und den Erkenntnisfortschritt führt zu enormem Flandlungsbedarf in Forschung und Entwicklung. Damit verbunden laufen derzeit vielfältige, ambitionierte Aktionen, z. B. bezüglich der Erstellung von Ontologien und Wissensgraphen. Das Knowhow entwickelt sich rasant, die Ansätze zur Implementation entstehen in verschiedenen Fachwelten bzw. mit unterschiedlichen Zielsetzungen parallel, so dass recht heterogene Herangehensweisen resultieren. Diese Veröffentlichung fokussiert auf Arbeiten, die derzeit als möglichst ganzheitlicher Ansatz für Materialdaten im Rahmen der Digitalisierungsinitiative „Plattform MaterialDigital" vorangetrieben werden. Die Autoren bearbeiten baustoffbezogene Aspekte im Verbundprojekt „LeBeDigital - Lebenszyklus von Beton". Zielsetzung ist die digitale Beschreibung des Materialverhaltens von Beton über den kompletten Herstellungsprozess eines Fertigteils mit einer Integration von Daten und Modellen innerhalb eines Workflows zur probabilistischen Material- und Prozessoptimierung. Es wird über die Vorgehensweise und die dabei gewonnenen Erfahrungen berichtet, nicht ohne den Blick auf die oft unterschätzte Komplexität der Thematik zu lenken. T2 - Ibausil 2023 CY - Weimar, Germany DA - 13.09.2023 KW - Beton KW - Digitalisierung KW - Datenmanagement KW - FAIR-Prinzip KW - Metadaten KW - Ontologie KW - Wissensgraph PY - 2023 AN - OPUS4-60964 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Birgit A1 - Dehn, F. A1 - Unger, Jörg F. A1 - Shepherd, D. A. A1 - Tamsen, Erik A1 - Pirskawetz, Stephan T1 - Wissensbasierte Digitalisierung von betontechnologischen Materialdaten N2 - Die sprunghaft zunehmende Wichtigkeit von FAIR- und Open-Data für die Qualitätssicherung, aber auch für die Nachnutzbarkeit von Daten und den Erkenntnisfortschritt führt zu enormem Flandlungsbedarf in Forschung und Entwicklung. Damit verbunden laufen derzeit vielfältige, ambitionierte Aktionen, z. B. bezüglich der Erstellung von Ontologien und Wissensgraphen. Das Knowhow entwickelt sich rasant, die Ansätze zur Implementation entstehen in verschiedenen Fachwelten bzw. mit unterschiedlichen Zielsetzungen parallel, so dass recht heterogene Herangehensweisen resultieren. Diese Veröffentlichung fokussiert auf Arbeiten, die derzeit als möglichst ganzheitlicher Ansatz für Materialdaten im Rahmen der Digitalisierungsinitiative „Plattform MaterialDigital" vorangetrieben werden. Die Autoren bearbeiten baustoffbezogene Aspekte im Verbundprojekt „LeBeDigital - Lebenszyklus von Beton". Zielsetzung ist die digitale Beschreibung des Materialverhaltens von Beton über den kompletten Herstellungsprozess eines Fertigteils mit einer Integration von Daten und Modellen innerhalb eines Workflows zur probabilistischen Material- und Prozessoptimierung. Es wird über die Vorgehensweise und die dabei gewonnenen Erfahrungen berichtet, nicht ohne den Blick auf die oft unterschätzte Komplexität der Thematik zu lenken. T2 - Internationale Baustofftagung (ibausil) CY - Weimar, Germany DA - 13.09.2023 KW - Beton KW - Digitalisierung KW - Materialdaten KW - Datenmanagement KW - FAIR-Prinzip KW - Metadaten KW - Ontologie KW - Wissengraph PY - 2023 UR - https://www.uni-weimar.de/de/bauingenieurwesen/institute/fib/ibausil/ VL - 2023 SP - 1 EP - 11 PB - Sonderausgabe des Online-Journals ce/papers von Wiley AN - OPUS4-58315 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 ED - Wang, K. ED - Shah, S.P. ED - Khayat, K. T1 - Casting process improvement by optimization of mixture composition and high range water reducing agent modification N2 - Since its invention in the early 1990’s, self-consolidating concrete has never become well established in the ready-mix sectors worldwide. The reason for this can be mainly found in the fact that the sophisticated compositions are sensitive against changing environments. This lack of robustness can be attributed to the interaction between cement hydration reaction and high range water reducing agent (HRWRA). Understanding the relevant mechanisms that control the initial flow performance as well as the flow retention helps optimizing SCC mixtures that perform either steadily in one specific environment or that perform largely similarly at steadily changing environments. This paper depicts how HRWRAs interact with clinker and hydration phases and discusses the important role of the charge density of a polycarboxylic HRWRA in the way the rheology is affected. Based on rheometric results and observations of the Vicat setting times, it is shown that increasing charge densities of the HRWRA and decreasing water to powder ratios (w/p) reduce the flow retention and have lesser retarding effect on the setting. Based on the discussion, optimization procedures for the mixture composition and the HRWRA modification are suggested to achieve optimized performance for varying environmental situations or highest robustness for specific conditions. T2 - SCC 2013 - 5th North American conference on the design and use of self-consolidating concrete CY - Chicago, IL, USA DA - 12.05.2013 KW - Polycarboxylate KW - Cement hydration KW - Adsorption KW - Mixture composition KW - Environmental conditions PY - 2013 SP - 1 EP - 10 AN - OPUS4-28581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Vasilic, Ksenija A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Stark, J. T1 - Experimental and numerical studies on calibration of a rotational rheometer for cementitious materials T2 - 17. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 2009-09-23 PY - 2009 SN - 978-3-00-027265-3 VL - 1 SP - 1-1135 - 1-1140 CY - Weimar AN - OPUS4-20300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Correlation between setting, heat evolution, and deformations of cementitious binder systems depending on type and amount of superplasticizer N2 - Today polycarboxylate ether based superplasticizer (PCE) is commonly used in concrete technology when high flow properties and water reduction are specified. The ionic strength of the polymers’ backbones determines the adsorption behaviour of polymers on clinker and early hydration products. The amount of required polymers for specified flow properties and the performance over the time of casting is thus determined by the molecular structure of the superplasticizer. The time depending consumption of polycarboxylate ether polymers strongly affects the reaction of aluminates and sulphate ions as well as the hydration process in general. Hence, the choice of polymers for particular flow properties greatly affects the very early properties of cementitious materials such as setting, heat evolution and autogenous deformations. In order to better understand how PCEs influence the early properties, mixes from cement, limestone filler, viscosity modifying agent and water were varied with a high and a low charge density superplasticizer in differing amounts. Results are presented from measurements with an automatic Vicat device, an isothermal heat flow calorimeter, and shrinkage cones. Tests were conducted at 5, 20, and 30 °C. It is shown that in presence of PCE the final set correlates well with the inflexion point of the heat flow curve, which emphasises the interrelation between C-S-H formation and setting. No such clear correlation can be found for the initial set, which is attributed to the fact that the initial set is rather a rheological than a structural phenomenon, so that other effects overlap with C-S-H formation. The results demonstrate that for a given polymer concentration low charge density polymers yield earlier setting than high charge polymers. However, this influence is overridden by the influence of the total amount of polymers in a cementitious system. Since PCE is typically added according to rheological specifications, and low charge PCE typically requires higher amounts of polymers than high charge PCE for comparable flow performance, low charge PCE retards setting more than high charge PCE. The paper furthermore points out that there is no significant influence of the polymer type or amount on the early deformations. Since type and amount strongly affect the hydration, it is demonstrated that early setting causes higher strain after the final set. It is hence concluded that higher PCE solid contents reduce the risk of early cracks that occur at time of setting, when a solid structure has already been formed but without resistance against cracks yet. T2 - 13th International congress on the chemistry of cement CY - Madrid, Spain DA - 03.07.2011 KW - Polycarboxylate superplasticizer KW - Setting KW - Heat evolution KW - Autogenous deformation KW - Self-compacting concrete KW - Calorimetry PY - 2011 SN - 978-84-7292-400-0 SP - 384 EP - 391 AN - OPUS4-24097 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Barthel, Maria A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Rogge, A. ED - Meng, B. T1 - Betonpflastersteine mit erweiterten Leistungsmerkmalen T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 PY - 2011 SN - 978-3-9814281-0-0 N1 - Geburtsname von Barthel, Maria: Meinel, M. - Birth name of Barthel, Maria: Meinel, M. SP - 194 EP - 203 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25182 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Meng, Birgit A1 - Kühne, Hans-Carsten A1 - Rosignoli, D. T1 - Development and application of a novel ready-made compound including additions and admixtures for the easy production of SCC - Entwicklung und Anwendung einer neuartigen Werktrockenmischung aus Zusatzstoffen und Zusatzmittel für die einfache Herstellung von SVB N2 - Im Rahmen des europäischen Forschungsprojekts Microcon wurden wirtschaftliche und ökologische Ansätze zur Verwendung von Feinstfüllstoffen – so genannten Microfillern – in Bauprodukten, die auf zementgebundenen Systemen basieren, untersucht. Hauptzielsetzung war die Entwicklung von modifizierten Bindemitteln und Zusätzen für die Transportbeton- und Fertigteilindustrie bis hin zur Marktreife. Eine der Neuentwicklungen war eine leicht handhabbare Werktrockenmischung für selbstverdichtenden Beton (SVB), die alle Schlüsselkomponenten bis auf das Bindemittel und die grobe Gesteinskörnung enthält und eine hohe Robustheit in der Anwendung gewährleistet. KW - Self-Compacting Concrete KW - Robustness KW - Microfiller KW - Rheology KW - On-Site Application III KW - Selbstverdichtender Beton KW - Robustheit KW - Mikrofiller KW - Rheologie KW - Baustellenanwendung PY - 2008 SN - 0373-4331 N1 - Sprachen: Deutsch/Englisch - Languages: German/English IS - 3 SP - 4 EP - 11 PB - Bauverl. BV CY - Gütersloh AN - OPUS4-17125 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit A1 - Brouwers, H.J.H. ED - Aguiar, J. B. ED - Jalali, S. ED - Camoes, A. ED - Ferreira, R.M. T1 - Influence of ambient temperature conditions on the effect of stabilising polymers in cementitious building materials T2 - 13th International Congress on polymers in concrete - ICPIC 2010 CY - Funchal-Madeira, Portugal DA - 2010-02-11 KW - Stabilising agent KW - Polycarboxylate ether KW - Polysaccharides KW - Starch ether KW - Biopolymers KW - Rheology KW - Setting PY - 2010 SN - 978-972-99179-4-3 SP - 241 EP - 248 CY - Funchal-Madeira, Portugal AN - OPUS4-21971 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kühne, Hans-Carsten A1 - Schmidt, Wolfram A1 - Meng, Birgit T1 - The influence of temperature on self-compacting concrete in presence of superplasticizer and additional admixtures T2 - 5th International RILEM Symposium on Self-Compacting Concrete CY - Ghent, Belgium DA - 2007-09-03 KW - Influence of temperature KW - Self-compacting concrete KW - SCC KW - Superplaticizer KW - Admixtures PY - 2007 SN - 978-2-35158-050-9 VL - 1 SP - 405 EP - 410 CY - Bagneux, France AN - OPUS4-15897 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Meng, Birgit T1 - Introduction to the MicroCon project T2 - Internationales und öffentliches Kolloquium "New Economical and Ecological Solutions to Reduce Raw Material Costs of Cement Based Products by Utilizing Micro Technology" CY - Berlin, Germany DA - 2006-11-29 PY - 2006 AN - OPUS4-14527 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Sonebi, M. A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Rheology modifying admixtures: The key to innovation in concrete technology - a general overview and implications for Africa N2 - Innovative admixture technology has significantly widened up the ränge of possibilities of concrete engineers. For many decades the water to cement ratio (w/c) was the major influencing factor for the performance of concrete. Due to the need to adjust a consistency, which still allowed reasonable workability, the w/c was typically significantly higher than technologically reasonable. Rheology modifying admixtures Support adjusting the concrete consistency largely independent of the w/c. It was only after the invention of the first superplasticizers that modern concrete technology significantly evolved in terms of flowability, strength, and durability, and only due to the steady evolution of the technology modern innovations, such as Self-Compacting Concrete, Ultra-High-Performance Concrete, or Engineered Cementitious Composites were made possible. Today’s superplasticizers are extremely versatile and can be adjusted to individual technologicalspecifications. However, the other side of the coin of versatility is that cementitious Systems incorporating superplasticizers have become more sensitive against environmental influences, such as the environmental temperature, which may cause unwanted effects or demand for supplementary admixture use such as stabilizing admixtures. Hence, concrete mixture composition with admixtures demands for a high level of expertise and offen there is lack of awareness about the mode of Operation of rheology modifying admixtures among concrete technologists. The paper gives a comprehensive overview about rheology modifying admixtures such as superplasticizers or stabilizing agents, and how they can be used depending upon the application in the most favourable way. Based on experiences with the sub-Saharan African concreting boundary conditions, which exhibit many challenges in terms of environmental boundary conditions and construction site logistics, conclusions are finally drawn, how admixtures can be used in the most beneficial way to improve the concrete casting Situation. KW - Rheology KW - Admixtures KW - Concrete KW - Superplasticizers KW - Polycarboxylate ether KW - Viscosity modifying agents PY - 2013 SN - 2224-3224 SN - 2225-0956 VL - 5 SP - 115 EP - 120 PB - International Institute for Conservation of Historic and Artistic Works CY - New York, NY, USA AN - OPUS4-30948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramge, Peter A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Grantham, M. ED - Mechtcherine, V. ED - Schneck, U. T1 - Influence of selected aspects of the mixture proportioning on the performance of repair mortars N2 - Due to the large number of individual constituents, the mixture modification of repair mortar is a complex task. It is almost impossible to change an individual property without influencing other mortar properties. Most properties can be altered by several different measures, which may vary in effectiveness, side effects and cost efficiency. In the presented paper, special attention is paid to the prevention of shrinkage induced constraining cracks, as this is crucial for the durability and service life of a concrete repair task. On the basis of the parameter studies it is shown how it may be beneficial, in certain cases, to accept the worsening of some general properties if by this measure another property, which is essential for the individual application task, can be enhanced significantly. Due to the complexity of the constituents' interactions in repair mortars, even apparently conflicting combinations of admixtures may become necessary. T2 - Concrete solutions 2011 - 4th International conference on concrete repair CY - Dresden, Germany DA - 26.09.2011 KW - Repair mortar KW - Concrete rehabilitation KW - Repair systems KW - Polymer cement concrete (PCC) KW - Sprayed polymer cement concrete (SPCC) PY - 2012 SN - 978-0-415-61-622-5 SP - 451 EP - 459 PB - Taylor & Francis CY - London AN - OPUS4-24567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Roussel, N. ED - Bessaies-Bey, H. T1 - A simple test method to assess the influence of PCEs on the rheology of flowable cementitious systems N2 - Today’s superplasticizers for self-compacting concrete and high Performance cementitious materials are very versatile. Typically superplasticizers are composed of a polycarboxylic backbone equipped with polyethylene oxide graft chains of variable length and grafting degree. The mode of operation of these admixtures is based on the steric repulsion of the particles upon adsorption. The adsorption is strongly depending upon the charge density of a superplasticizer and the time dependent Adsorption processes control the retention of the flow performance – an important issue particularly for ready-mix and construction site concrete. However, the properties of polycarboxylic superplasticizers typically remain a black box for users. The paper suggests a simple and rapid test method, which can be conducted without sophisticated equipment, to qualitatively distinguish between two types of superplasticizers based on the adsorption mechanism. Interpreting the results in the right way provides a powerful tool to choose the right admixture for individual time dependent flow specifications. T2 - 1st international RILEM conference on rheology and processing of construction materials and 7th RILEM conference on self-compacting concrete CY - Paris, France DA - 02.09.2013 KW - Adsorption KW - Polycarboxylate ether KW - Rheology KW - Slump flow PY - 2013 SN - 978-2-35158-137-7 IS - Chapter 2.1.1 SP - 1 EP - 8 AN - OPUS4-29929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schraut, Katharina A1 - Adamczyk, Burkart A1 - Adam, Christian A1 - Stephan, Dietmar A1 - Meng, Birgit A1 - Simon, Sebastian A1 - von Werder, Julia A1 - Hirsch, Tamino A1 - Manninger, Tanja T1 - Effect of gypsum on the hydration of fused cement clinker from basic oxygen furnace slag N2 - Fused cement clinker can be produced from molten basic oxygen furnace slag (BOFS) by way of a reductive thermochemical treatment. During the thermochemical treatment, oxidic iron is reduced to metallic iron and separated. The resulting low-iron slag has a chemical and mineralogical composition similar to ordinary Portland cement (OPC) clinker. In this study, the hydraulic reactivity of the fused clinker from BOFS with and without gypsum was investigated using isothermal calorimetry, differential scanning calorimetry, in situ X-ray diffraction and powder X-ray diffraction. Furthermore, a synthetic fused clinker without foreign ions and fused clinker produced by a mixture of both materials was studied. The hydraulic reaction of the fused clinker from BOFS was considerably slower than that of OPC. However, the reaction can be accelerated by adding gypsum as a sulfate carrier. Furthermore, the results showed an increased reaction rate with decreasing content of foreign ions such as Fe, P or Mn. KW - General Materials Science KW - Building and Construction PY - 2024 DO - https://doi.org/10.1680/jadcr.23.00070 SN - 0951-7197 SP - 1 EP - 19 PB - Telford AN - OPUS4-59391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schraut, Katharina A1 - Adamczyk, Burkart A1 - Simon, Sebastian A1 - von Werder, Julia A1 - Meng, Birgit A1 - Stephan, D. A. A1 - Adam, Christian T1 - Zementklinker durch Nachbehandlung von Stahlwerksschlacken N2 - Die Klinkerphasenbildung durch Sinterung in Drehrohröfen bei der Herstellung von Portlandzementklinker (PZK) ist gründlich erforscht und optimiert. Im Hinblick auf mögliche ökonomische und ökologische Vorteile befassen sich aktuelle Forschungsvorhaben darüber hinaus mit der Herstellung von Klinkermineralen aus Stahlwerksschlacken, die eine vergleichbare chemische Zusammensetzung aufweisen. Neuste Untersuchungen zeigen, dass nach der reduzierenden Behandlung schmelzflüssiger Linz-Donawitz-(LD)-Schlacken und Abscheidung des gebildeten metallischen Eisens eine mineralische Schlacke entsteht, die unabhängig von ihren Abkühlbedingungen ca. 50–60 Gew.% des wichtigsten Klinkerminerals Alit (C3S) enthält und eine hohe hydraulische Reaktivität aufweist. Die Stabilität des Alits auch nach langsamer Abkühlung deutet auf eine Stabilisierung des Minerals durch Nebenelemente aus den LD-Schlacken hin. Ein sinkender Anteil an LD-Schlacke durch Zusatz synthetischer Schlackemischung, die sich hinsichtlich ihrer Hauptkomponenten wie eine ausreduzierte LD-Schlacke zusammensetzt, führt zu einem Rückgang des Alitgehaltes und dem Zerfall der Schlacke beim Erstarren. T2 - 5. Schlacken-Symposium CY - Meitingen, Germany DA - 25.10.2018 KW - LD-Schlacke KW - Zement KW - Tricalciumsilikat PY - 2018 SP - 219 EP - 229 PB - Max Aicher Unternehmensgruppe AN - OPUS4-46412 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stohl, Leonie A1 - Manninger, Tanja A1 - von Werder, Julia A1 - Dehn, F. A1 - Gorbushina, Anna A1 - Meng, Birgit T1 - Bioreceptivity of concrete - A review N2 - Materials that support natural biodiversity on their surfaces can compensate for human activities that have a negative impact on nature and thus contribute to a carbon-neutral and nature-positive world. Specifically designing bioreceptive materials which favor the growth of biofilms on their surface is an approach complementing conventional, macroscopic green façades. But what exactly characterizes a bioreceptive substrate and how do biofilm and substrate interact? How and why does a spontaneous colonization and the formation of biofilms take place? What are biofilms and how can they be established in a laboratory setting? How can this existing knowledge be transferred to the artificial stone concrete so that this material can be tuned to increase (or decrease) its bioreceptivity? This review paper aims at summarizing the existing state of knowledge on bioreceptive concrete and pointing out inconsistencies and contradictions which can only be removed by more interdisciplinary research in the field. KW - Bioreceptivity KW - Biofilm KW - Green facades KW - Developing building materials KW - Surface interactions KW - Concrete PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581685 DO - https://doi.org/10.1016/j.jobe.2023.107201 SN - 2352-7102 VL - 76 SP - 1 EP - 17 PB - Elsevier AN - OPUS4-58168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Temperature related effects on self-consolidating concrete due to interactions between superplasticizers, supplemental admixtures and additions T2 - 9th ACI International conference on superplasticizers and other chemical admixtures in concrete CY - Seville, Spain DA - 2009-10-12 KW - Polycarboxylate KW - Modified starch KW - Rheology KW - Self-compacting concrete KW - Temperature KW - Setting KW - Shrinkage KW - Heat evolution PY - 2009 SN - 978-0-9731507-8-0 SP - 135 EP - 147 AN - OPUS4-20884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -