TY - CONF A1 - Schmidt, Wolfram T1 - Zum Einfluss von Fließmitteln auf die frühe Zementhydratation T2 - Vortragsreihe der Fakultät für Bauingenierwissenschaften der TU Graz CY - Graz, Austria DA - 2014-10-02 PY - 2014 AN - OPUS4-31687 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Rogge, A. ED - Meng, B. T1 - Zum Einfluss des Mischungsentwurfs und des Fließmittels auf temperaturbedingte Veränderungen der Rheologie von SVB T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 KW - Fließmittel KW - Polycarboxylatether KW - Selbstverdichtender Beton KW - Temperatureffekte KW - Rheologie PY - 2011 SN - 978-3-9814281-0-0 SP - 40 EP - 49 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25194 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Zum Einfluss des Mischungsentwurfs und des Fließmittels auf temperaturbedingte Veränderungen der Rheologie von SVB T2 - 52. DAfStb-Forschungskolloquium, BAM CY - Berlin, Germany DA - 2011-11-07 PY - 2011 AN - OPUS4-25129 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 T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 2012-09-12 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 - 2-0399 AN - OPUS4-26543 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit A1 - Brouwers, H.J.H. T1 - Zum Einfluss der Menge und Modifikation des Fließmittels auf das Erstarren, die Wärmeentwicklung und die frühen Verformungen von Bindemittelleimen T2 - 18. Internationale Baustofftagung CY - Weimar, Germany DA - 2012-09-12 PY - 2012 AN - OPUS4-26729 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Zum Einfluss der Fließmittelmodifikation auf die Verarbeitungseigenschaften fließfähiger Betone - Hintergründe und Optimierungspotential T2 - betonbau.aktuell 2014 CY - Apolda, Germany DA - 2014-02-13 PY - 2014 AN - OPUS4-30831 LA - deu 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-464769 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 - JOUR A1 - Schmidt, Wolfram T1 - Wirkungsweise verschiedener Fließmittel N2 - In den vergangenen Jahrzehnten hat sich die Betonbauweise beträchtlich von einer Massenanwendung hin zu einer innovativeren, zukunfts- und leistungsorientierten Werkstofftechnologie weiterentwickelt. Heutzutage besteht Beton nicht mehr länger nur aus Zement, Wasser und Gesteinskörnungen, sondern kann unter Anwendung von Zusatzstoffen und chemischen Zusatzmitteln erheblich verbessert werden. Gleichzeitig beschränken die Betonspezifikationen sich nicht mehr auf den Elastizitätsmodul und Druckfestigkeit, sondern Beton kann ebenfalls zur Erfüllung zahlreicher Anwendungskriterien wie Dauerhaftigkeit, Verarbeitbarkeit, Ästhetik, Brandverhalten und vieler anderer mehr beitragen. Gleichzeitig ist jedoch die Zusammensetzung von Beton wegen der Vielzahl an interagierenden Mischungskomponenten komplizierter geworden. Das Verständnis der Auswirkungen der veränderten Mischungskomponenten ist eine Herausforderung, aber auch der Schlüssel zu einer innovativen Betontechnologie. PY - 2015 SN - 1439-7706 VL - 3 SP - 2 EP - 6 PB - ad-media-Verl. CY - Köln AN - OPUS4-33727 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - 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 - CONF A1 - Schmidt, Wolfram A1 - Radlinska, Aleksandra A1 - Nmai, Charles A1 - Buregyeya, Apollo A1 - Shicong Kou, Wai Lok Lai T1 - Why does Africa need African Concrete? An Observation of Concrete in Europe, America and Asia - and Conclusions for Africa T2 - International Conference on Advances in Cement and Concrete in Africa CY - Johannesburg, South Africa DA - 2013-01-28 PY - 2013 AN - OPUS4-28461 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -