TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Improvement of durability of SCC by the use of micro fly ash and limestone filler T2 - BAM-Präsentation Nanocem-Meeting CY - Copenhagen, Denmark DA - 2006-04-25 PY - 2006 AN - OPUS4-12475 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Entwicklung eines selbstverdichtenden Betons mit inerten Zusatzstoffen-Prüfung nach europäischer Richtlinie für SVB N2 - Im Rahmen von MICROCON, einem europäischen CRAFT-Projekt, besteht eine wesentliche Zielsetzung in der Optimierung von selbstverdichtendem Beton (SVB) im Hinblick auf Kosten und Leistungsfähigkeit durch den Einsatz von teilweise puzzolanischen Microfillern. Um die Puzzolanität bei der Beurteilung besser bewerten zu können, wird ein Referenzbeton benötigt, der aus weitestgehend inerten Zusatzstoffen besteht. Die Entwicklung eines solchen Referenzbetons fand an der BAM nach der japanischen Methode nach Okamura statt. T2 - Wissenschaftsrat CY - Berlin, Germany DA - 17.02.2006 PY - 2006 AN - OPUS4-12030 LA - deu 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 - TY - JOUR A1 - Schmidt, Wolfram A1 - Wend, Dirk A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - The influence of superplasticiser modifications on early hydration processes N2 - Self-compacting concrete (SCC) differs substantially from normal concrete as regards the quantity of superplasticiser dosage. The functionality of superplasticisers, based on the polycarboxylate ether (PCE) superplasticiser customary with SCC, is nowadays very well understood at construction material research level. However, knowledge concerning pertinent correlations does not always permeate practice to an equal extent. PCEs are extremely polymorphic as opposed to earlier superplasticiser groups, which still possess a considerable proportion of the superplasticiser market. The geometry of polymers can be adjusted individually to performance characteristics required for certain uses. Yet, in selecting a superplasticiser for its specified rheological properties, a very strong influence can equally be exerted simultaneously on the subsequent hydration process. The charge density of the PCE employed also plays a key role in connection with both rheology and early hydration. KW - Rheology KW - Early cement hydration KW - Polycarboxylate ether vicat KW - Shrinkage PY - 2012 SN - 1437-9023 VL - 4 SP - 64 EP - 69 PB - ad-media-Verl. CY - Köln AN - OPUS4-26355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Wend, Dirk A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Einfluss der Fließmittelmdoifikation auf Prozesse während der frühen Hydratation von selbstverdichtenden Bindemitteln KW - Rheologie KW - Frühe Zementhydratation KW - Polycarboxylatether KW - Vicat KW - Schwinden PY - 2012 SN - 1439-7706 VL - 4 SP - 66 EP - 71 PB - ad-media-Verl. CY - Köln AN - OPUS4-26356 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Gluth, Gregor T1 - Importance of Cement Proficiency Testing T2 - SPIN Meeting and Cement and Concrete Workshop CY - Dar Es Salaam, Tanzania DA - 2012-07-01 PY - 2012 AN - OPUS4-26399 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 - 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 - Meng, Birgit A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten ED - Rogge, A. ED - Meng, B. T1 - Aktuelle Forschungsansätze zur Rheologie von Frischbeton T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 KW - Baustoffe KW - Beton KW - Frischbeton KW - Rheologie PY - 2011 SN - 978-3-9814281-0-0 SP - 33 EP - 39 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25195 LA - deu 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 - CONF A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten ED - Rogge, A. ED - Meng, B. T1 - Cement and concrete development in Africa: the role of the SPIN project T2 - 52. DAfStb-Forschungskolloquium CY - Berlin, Deutschland DA - 2011-11-07 PY - 2011 SN - 978-3-9814281-0-0 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. SP - 339 EP - 344 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-25172 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Challenges of the African Environmental Conditions for Concrete Mixture Compostion T2 - Workshop "Cement and Concrete for Africa", BAM CY - Berlin, Germany DA - 2011-08-17 PY - 2011 AN - OPUS4-24726 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Gluth, Gregor A1 - Kühne, Hans-Carsten T1 - LightSHIP Lightweight Construction - Scientific Cooperation for Housing with Innovative Panel Technology T2 - Workshop Cement and Concrete for Africa, BAM CY - Berlin, Germany DA - 2011-08-17 PY - 2011 AN - OPUS4-24727 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten T1 - SPIN- Spearhead network for innovative,clean and safe cement & concrete technologies N2 - Worldwide, cement and concrete experts are at the cutting-edge to sustainable, green, healthy but nonetheless high-Performance concrete. The current relatively low development of the cement and concrete industry in Africa offers the unique opportunity to start directly on the best achievable and sustainable Level, if only Expertise is sufficiently available. It should not be neglected that concrete is a product with comparably low Transport ranges, which means that an improved concrete market will mainly Support the local economy without exceeding financial Drains to the international market, thus fostering the fight against poverty, which is an urgent Need in most African countries. T2 - Workshop Cement and Concrete for Africa CY - Berlin, Germany DA - 17.08.2011 PY - 2011 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-24728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - The SPIN network for knowledge-driven, sustainable and clean cement and concrete technology in Africa - Practical experiences from international research cooperation between Europe and Africa T2 - 2nd Joint Stakeholder Conference of the EDULINK and the ACP Science and Technology (ACP S&T) programmes CY - Brussels, Belgium DA - 2011-10-26 PY - 2011 AN - OPUS4-24743 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Vasilic, Ksenija A1 - Kühne, Hans-Carsten A1 - Meng, Birgit A1 - Roussel, Nicolas T1 - Modelling of fresh SCC flow through reinforced sections T2 - 52. DAfStb-Forschungskolloquium, BAM CY - Berlin, Germany DA - 2011-11-07 PY - 2011 AN - OPUS4-25128 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 - JOUR A1 - Kühne, Hans-Carsten A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Uzoegbo, H. C. T1 - Building practice and concrete infrastructure development in eastern and southern Africa N2 - The construction sector has traditionally been a source of employment in African regions. However, due to policy changes, cut backs in public investments as well as a fall in the number of employments in the private sector have been observed in many countries. Furthermore a shift from registered companies to informal contractors could be noticed. Many contractors offer services they do not provide permanently or for which the required equipment has to be borrowed. A study that was published in 2000 about the situation in Tanzania pointed out that only ca. 15% of the enterprises that offer concrete works own a concrete mixer. The building practice with concrete varies widely over the African continent. Whereas the level of technology and the infrastructure for cement and concrete in South Africa is elaborate, in East Africa and particularly those that were heavily suffering from civil war during the nineties of the last century, the availability of cement and concrete is poor and these materials are far from being everyday building practice. Most of the population relies on indigenous forms of construction requiring wood obtained from felling of forest trees and ultimately contributing to de-forestation. Informal settlements in South-Africa and Kenya are literal evidence where originally green natural vegetation has been turned into artificial desert-like landscapes. PY - 2011 SN - 1437-9023 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 3 SP - 32 EP - 37 PB - ad-media-Verl. CY - Köln AN - OPUS4-25360 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - 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 - CONF A1 - Schmidt, Wolfram T1 - Challenges of the African environmental conditions for concrete mixture composition N2 - Concrete technology was exposed to a rapid development during the last three decades. For the longest time in its history, concrete was considered as a three component System consisting of aggregates, which are bound by the hardened cement paste consisting of hydrated cement. Traditionally, the only way of adjusting the consistency of concrete was using well adjusted aggregates and grading curves and adding excess water to the concrete, accepting that the latter in return reduces strength and durability. During the last three decades, however, concrete has developed further from a three component System towards an (at least) five component system, since the use of mineral additions and Chemical admixtures has become state of the art. Both components are able to enhance the workability, the compactability, and the density of the microstructure with effects on strength, ductility and durability, while cement can be saved in parallel. Due to reasonable use of admixtures and additions, concrete can be designed to match mechanically high performance specifications. Traditionally, cement paste was considered the weakest component in concrete. Flowever, in modern concrete a good paste composition can yield highest performance, passing the role of the mechanical bottleneck towards the aggregates. T2 - Workshop cement and concrete for Africa CY - Berlin, Germany DA - 17.08.2011 KW - Cement KW - Concrete KW - Mixture composition KW - Africa KW - Climatic conditions PY - 2011 SN - 978-3-9814281-4-8 SP - 37 EP - 49 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-24780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - The SPIN project N2 - Globally, cement and concrete experts are at the cutting-edge to sustainable, green, healthy but nonetheless high-performance concrete. In the present age, concrete is not yet well established in Africa, which öfters the unique opportunity to build up a cement and concrete market based on the highest available state of technology. As this industry needs high level expertise, a central issue in implementation of skilled technology is cross-linking research institutions and laboratories. It should not be neglected that concrete is a product with comparably low transport ranges, which means that an improved concrete market will mainly support the local economy without exceeding financial drains to the international market, thus fostering the fight against poverty, which is an urgent need in most African countries. The SPIN project highlights recent developments in the field of cement and concrete research with impact on the local and global economy. Challenges, future developments and opportunities for the African construction industry are in the focus. The SPIN project is funded by the European Commission (EC) and supported by the African, Caribbean and Pacific (ACP) Group of States under the project body of the ACP Science and Technology Programme. SPIN is acronym for “Spearhead network for Innovative, Clean and Safe Cement and Concrete Technologies”. The project aims to cross-link experts with industry and policy making bodies, aiming to establish sustainable cement and concrete construction in Africa. T2 - Workshop cement and concrete for Africa CY - Berlin, Germany DA - 17.08.2011 PY - 2011 SN - 978-3-9814281-4-8 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. SP - 5 EP - 9 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-24778 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Optimierung der Robustheit von selbstverdichtendem Beton gegenüber Temperatureinflüssen N2 - Selbstverdichtender Beton verhält sich unter Temperatureinfluss anders als Normalbeton, da die Rheologie neben der fortschreitenden Hydratation zusätzlich durch die von der Zeit und dem Hydratationsfortschritt abhängige Adsorption von Fließmitteln beeinflusst wird. Anhand rheometrischer Betonversuche an SVB unterschiedlicher Entwurfskonzepte mit variierter anionischer Ladungsdichte im Fließmittel wird verdeutlicht, dass mehlkornreiche SVB bei niedrigen Temperaturen sehr robust sind, während bei hohen Temperaturen mehlkornärmere Entwürfe zu bevorzugen sind. Darüber hinaus wird gezeigt, wie sich unterschiedliche Fließmittelmodifikationen in bestimmten Temperaturbereichen verhalten. Anhand des Wasser-Feststoff-Verhältnisses und des Adsorptionsverhaltens von Fließmitteln werden die maßgeblichen Prozesse erläutert und Möglichkeiten für die Entwicklung robuster Mischungen für individuelle Temperaturbereiche aufgeführt.-------------------------------------------------------------------------------------------------------------------------------------------------------------- Regarding the temperature dependent performance, self-compacting concrete (SCC) distinguishes from normal concrete, since its rheology does not only depend upon the hydration itself but supplementary upon the adsorption of superplasticizers, which is affected by the time and the hydration progress. Based on rheometric concrete investigations with different SCC mixture compositions and varied anionic charge densities of the superplasticizers, it is shown that SCC, which is rich in powder components, shows robust performance at low temperatures, while compositions with lower powder contents are favourable at high temperatures. Furthermore, the performance of different superplasticizer modifications at different temperature ranges is demonstrated. The relevant processes are explained by means of the water to powder ratio as well as the adsorption behaviour of superplasticizers, and options for the development of robust mixture compositions for individual temperature ranges are itemised. KW - Betontechnologie KW - Hochleistungsbeton KW - Praxis KW - Rheologie KW - Mischungsentwurf KW - Selbstverdichtender Beton KW - Fließmittel KW - Temperatur KW - Frischbetoneigenschaften KW - Robustheit KW - Baustoffe KW - Versuche PY - 2013 U6 - https://doi.org/10.1002/best.201200051 SN - 0005-9900 SN - 1437-1006 VL - 108 IS - 1 SP - 13 EP - 21 PB - Ernst CY - Berlin AN - OPUS4-27699 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Akindahunsi, A. A. A1 - Schmidt, Wolfram A1 - Uzoegbo, H.C. A1 - Iyuke, S.E. ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - The influence of starches on some properties of concrete N2 - Starches and its derivatives are known to exhibit viscosity modifying characteristics. In an ongoing work, the influence of com and cassava starches on some properties of concrete such as compressive strength, heat of hydration and creep are examined. Various percentages (0.0, 0.5, 1.0, 1.5 and 2 %) of starches by weight of cement were added to concrete mixes prepared in the laboratory. Preliminary results of compressive strengths showed that both starches have some positive impact (e.g. there was 5.3 % increase in strength due to a 1 % addition of com starch by weight of cement in comparison to the control while cassava starch of the same percentage gave 4.9 % increase in strength) at certain percentages of starch addition to concrete at 28 days. The creep and hydration results shows the starch additions compares well and in some instance performs better. T2 - ACCTA - International conference on advances in cement and concrete technology in Africa 2013 CY - Johannesburg, South Africa DA - 28.01.2013 KW - Starches KW - Concrete KW - Compressive strength KW - Heat of hydration KW - Creep PY - 2013 SN - 978-3-9815360-3-4 SP - 637 EP - 645 AN - OPUS4-27756 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramge, Peter A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - Effect of the storage of cement on early properties of cementitious systems N2 - As soon as cement is mixed with water, the hydration reaction starts to set of. The progression of the hydration process is governed by the amount and the availability of water and its possibility to access the unhydrated cement grain surfaces. For a total hydration cement theoretically requires water amounting approximately 0.38 of its own mass. Nevertheless, due to the cement’s highly hygroscopic nature, already the moisture in the ambient air can cause first hydration reactions to set in upon the cement grain surfaces. Such pre-hydration processes have an effect on the cement's properties. Dpending on the specific conditions during the storage the significance of the impact on certain properties can vary. If cement is consumed soon after production and is transported only short distances in a silo wagon to its final destination for immediate use without further stock transfer, the effects are rather negligible. However, if cement is delivered in bags, transported over long distances, shifted serval times and stored for longer time periods until it is finally consumend, these effects can be quite severe. Due to the actual logistical situation with comparably few cement plants, large delivery distances and partially less developed infrastructures, the latter scenario pictures the situation for the most cases in Africa quite well. In order to verify the relevance of the pre-hydation for practical application, a series of tests was conducted at the German Federal Institute for Materials Research and Testing (BAM). The influence of the cement storage on gresh and hardened concrete properties was investigated for different concrete and mortar types. The investigations show that the impact of the storage conditions is more pronounced for specialized concretes with high sophisticated optimized mixture compositions containing admixtures. Nevertheless, the effects also occur for ordinary concrete and should not be ignored. 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 - Storage KW - Ambient conditions KW - Hydration KW - Pre-hydration KW - Atmospheric humidity PY - 2013 SN - 978-3-9815360-3-4 SP - 339 EP - 347 AN - OPUS4-27757 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Mixture Proportioning for Rubustness of Concrete Properties T2 - ACCTA 2013, Pre-Conference Workshops CY - Johannesburg, South Africa DA - 2013-01-25 PY - 2013 AN - OPUS4-27674 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Admixtures for Innovative Concrete - Rheological Basics and Rhelogy Modifying Admixtures T2 - ACCTA 2013, Pre-Conference Workshop CY - Johannesburg, South Africa DA - 2013-01-25 PY - 2013 AN - OPUS4-27675 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten T1 - Rheological Optimisation for Flowable Mixture Compositions Specified for African Boundary Conditions T2 - International Conference on Advances in Cement and Concrete in Africa CY - Johannesburg, South Africa DA - 2013-01-28 PY - 2013 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-27676 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten 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 - CONF A1 - Schmidt, Wolfram A1 - Uzoegbo, H.C. A1 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten A1 - Rogge, Andreas ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - Experiences in an African-European-cooperation project: strengthening research capacity in cement and concrete in Africa N2 - This report is based on a three-year experience as coordinator of the ACP-EU funded SPIN project. The project involved eight African and three European partners. Practical and unforeseeable problems are addressed that occurred during the project implementation and ways how they were successfully solved are reported. The major problems in many African institutions were administrations that are not used to work in multi-national consortia and a lack of institutional support for the African researchers. In Europe a misjudgement of the African boundary conditions as well as inflexible administrations caused problems. Finally the funding scheme did not always allow to easily overcome the high number of unexpected practical problems. A major deficit identified during the project was a general trend in Africa to underestimate the role of research for the development of the continent. Most universities focus on teaching applied sciences, which is without doubt important to cover the market need for qualified staff in the rapidly growing African industries. However, this makes it unattractive for highly qualified performers to conduct research on the continent. Furthermore this leads to the situation that the curricula can only contain second hand knowledge. In order to attract international high level researchers, it is suggested to install multi-national regional excellence research centres that only promote PhD and post-doc research on a level that can cope with highest international excellence. High level research is often perceived as not capable of focusing on immediate actual problems that many African economies have to cope with.. However, it is considered to be very sustainable in terms of autonomy and mastering future challenges. T2 - ACCTA - International conference on advances in cement and concrete technology in Africa 2013 CY - Johannesburg, South Africa DA - 28.01.2013 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 - 1177 EP - 1184 AN - OPUS4-27762 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - Rheological optimisation for flowable mixture compositions specified for African boundary conditions N2 - To date concrete technology is not yet well established in sub-Saharan Africa but considering the construction technological challenges of the region, without doubt, concrete will play a major role in future. The social, economic, and geographic boundary conditions distinguish greatly from those that can be found in many other regions of the world, where concrete is considerably well established. Düring the last decades, concrete technology underwent a rapid evolution process, but in most countries, where concrete is already well established, innovations are difficult to be brought into practice, Africa, currently has the opportunity and potential, of directly establishing the best available practice in concrete technology. The conclusion is drawn that self-compacting concrete (SCC) or highly flowable concrete is a reasonable solution for African construction sites. Since on most African construction sites the disadvantageous concreting environment is the most crucial factor for the concrete quality, the outstanding workability properties outweigh any disadvantages of SCC. Based on this consideration, concepts are developed, how to bring about robust SCC cost-efficiently and reliably into practice as pre-mixed dry compound under consideration of local materials such as rice husk ashes, bagasse ashes, natural pozzolans, cassava starch and lignosulphonate. T2 - ACCTA - International conference on advances in cement and concrete technology in Africa 2013 CY - Johannesburg, South Africa DA - 28.01.2013 KW - Mixture composition KW - Rheology KW - Climatic conditions KW - Admixtures KW - Additions 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 - 359 EP - 366 AN - OPUS4-27764 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 - 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 - Barthel, Maria A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten ED - Uzoegbo, H.C. ED - Schmidt, Wolfram T1 - Concrete pavers for the mitigation of the urban heat island effect T2 - ACCTA - International conference on advances in cement and concrete technology in Africa 2013 CY - Johannesburg, South Africa DA - 2013-01-28 KW - Urban heat island effect KW - Earth-moist concrete KW - Concrete multilayers pavers KW - Water storage KW - Self-cooling pavement PY - 2013 SN - 978-3-9815360-3-4 SP - 953 EP - 960 AN - OPUS4-27769 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 - Schmidt, Wolfram T1 - Influence of the processing temperature and combined admixtures on the properties of Self-Compacting Concrete T2 - 7th International PhD Symposium in Civil Engineering CY - Stuttgart, Germany DA - 2008-09-11 PY - 2008 IS - Kap. 16.8 SP - 75 EP - 84 AN - OPUS4-17948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Performance and interactions of admixtures for SCC exposed to different climatic conditions T2 - CONSEC'07 Tours Concrete under Severe Conditions, CY - Tours, France DA - 2007-06-04 PY - 2007 AN - OPUS4-14874 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 - JOUR A1 - Kühne, Hans-Carsten A1 - Schmidt, Wolfram T1 - Der Siebtrennversuch nach prEN 12350-11 KW - SCC KW - SVB KW - Prüfverfahren KW - Sedimentation KW - Siebtest KW - EN 12350-11 PY - 2007 SN - 0005-9846 VL - 57 IS - 10 SP - 448 EP - 454 PB - Verlag Bau + Technik CY - Erkrath AN - OPUS4-16148 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kühne, Hans-Carsten A1 - Schmidt, Wolfram T1 - Spezifische Einflüsse der Mischtechnik auf Beton T2 - Mischseminar Betonmarketing Ost "Moderne Betone wirksam mischen" CY - Berlin, Germany DA - 2007-10-30 PY - 2007 AN - OPUS4-16171 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Einfluss der Verarbeitungstemperatur auf die Eigenschaften von SVB bei Verwendung von Fließmittel und weiteren Zusatzmitteln N2 - Nachdem vor ca. 20 Jahren in Japan die Entwicklung der selbstverdichtenden Betone begann, dauerte es weitere 10 Jahre, bis diese Entwicklung auch Europa erreichte. Obwohl im Fertigteilsektor bereits deutlich mehr SVB zum Einsatz kommt als im Transportbetonbereich, bleiben die Produktionsmengen hinter dem zurück, was die Potenziale und Chancen dieser Technologie eigentlich erwarten ließen. Eine Ursache für die geringe Marktverbreitung sind die stark schwankenden und teilweise nur schwer beherrschbaren Frischbetoneigenschaften dieser Betone. KW - SVB KW - SCC KW - Zusatzmittel KW - Rheologie KW - Fließmittel Betontechnologie KW - Frischbetoneigenschaften PY - 2007 SN - 0373-4331 IS - 12 SP - 40 EP - 49 PB - Bauverl. BV CY - Gütersloh AN - OPUS4-16444 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - 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 - JOUR A1 - Schmidt, Wolfram A1 - Ramge, Peter A1 - Kühne, Hans-Carsten T1 - Einfluss der Lagerungsbedingungen von Zement auf die Verarbeitungs- und Erhärtungseigenschaften von Beton = Effect of the storage conditions of cement on the processing and hardening properties of concrete N2 - In Produktionspausen können in Betonwerken nennenswerte Lagerungsintervalle entstehen. Auf Baustellen und in den Instandsetzungen werden Zement- und Trockenmörtelsäcke teilweise über längere Zeiträume gelagert. Auch im Zusammenhang mit Zementimporten und zunehmend filigran abgestimmten Betonrezepturen die bereits bei kleinen Änderungen der Ausgangsstoffe sensibel reagieren, nimmt die Relevanz der Zementlagerung zu. Aus diesem Grund wurde der Einfluss der Zementlagerung auf die Eigenschaften von Betonen in einer Versuchsreihe an der Bundesanstalt für Materialforschung und -prüfung (BAM) ermittelt. KW - Alterung KW - Zement KW - Sulfationengehalt KW - C3A KW - Rheologie KW - Ageing KW - Cement KW - Sulphate ion content KW - Rheology PY - 2009 SN - 0373-4331 SN - 1865-6528 N1 - Sprachen: Deutsch/Englisch - Languages: German/English VL - 75 IS - 6 SP - 10 EP - 17 PB - Bauverl. CY - Gütersloh AN - OPUS4-19747 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Ramge, Peter A1 - Kühne, Hans-Carsten T1 - Efecto de las condiciones de almacenamiento del cemento en las propiedades de procesamiento y endurecimiento del hormigón / As consequências das condicoes de armazenamento do cimento nas qualidades do processamento e endurecimento do concreto PY - 2009 SN - 0373-4331 SN - 1865-6528 N1 - Sprachen: Spanisch/Portugiesisch - Languages: Spanish/Portuguese VL - 3 SP - 2 EP - 9 PB - Bauverl. CY - Gütersloh AN - OPUS4-20239 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Möglichkeiten zur Steuerung der Robustheit von selbstverdichtendem Beton gegenüber veränderlichen Umgebungstemperaturen T2 - DAfStb Doktorandensymposium 2010 - 51. Forschungskolloquium CY - Kaiserslautern, Germany DA - 2010-11-11 PY - 2010 AN - OPUS4-22709 LA - deu 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 - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Meng, Birgit A1 - Brouwers, H.J.H. T1 - Effect of superplasticizer and stabilising agent type on fresh concrete performance of SCC at varied ambient temperatures T2 - SCC2010 6th Int. RILEM Symposium on Self-Compacting Concrete - 4th North American Conference on the Design and Use of SCC CY - Montreal, Canada DA - 2010-09-26 PY - 2010 AN - OPUS4-20855 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 - Temperature related Effects on Self-Consolidating Concrete due to Interactions between Superplasticizers, supplemental Admixtures and Additions T2 - 9th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Seville, Spain DA - 2009-10-12 PY - 2009 AN - OPUS4-20856 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schmidt, Wolfram A1 - Brouwers, J. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit ED - Khayat, K. H. ED - Feys, D. T1 - Effects of superplasticizer and viscosity-modifying agent on fresh concrete performance of SCC at varied ambient temperatures N2 - Varying ambient temperatures in plants or on construction sites during casting of SCC can cause serious problems affecting the fresh concrete performances, such as rheological properties and setting time, with consequences for the hardened properties in the structure. By sensible choices of the components, the robustness of SCC mixtures against temperature variations can be improved. However, this aspect has not been the focus of intensive research yet. In this study the effects of varied ambient temperatures on the early performance of differently composed SCC mixtures are investigated, with emphasis on changes in rheology, early deformations, heat evolution and setting. Focus is placed on the study of the influence of the polycarboxylate ether molecule type as well as different viscositymodifying agents on the temperature robustness. Effects on the relevance for practical concrete applications are evaluated, which will provide a reliable framework of possible actions on the appropriate use of admixtures for SCC. T2 - SCC 2010 - 6th International RILEM Symposium on self-compacting concrete / 4th North American conference on the design and use of SCC - Desgin, Production and Placement of self-consolidating concrete CY - Montreal, Canada DA - 2010-09-26 KW - Polycarboxylate KW - Modified starch KW - Rheology KW - Self-compacting concrete KW - Temperature KW - Yield stress KW - Viscosity PY - 2010 SN - 978-90-481-9663-0 U6 - https://doi.org/10.1007/978-90-481-9664-7_6 N1 - Serientitel: RILEM bookseries – Series title: RILEM bookseries VL - 1 IS - 2 SP - 65 EP - 77 PB - Springer AN - OPUS4-22126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Influence of environmental temperatures on the performance of polymeric stabilising agent in fresh cementitious materials N2 - Stabilising admixtures are commonly used additives in repair mortars and grouts. Beyond this, such type of admixture is increasingly used in concrete and other cementitious materials. In particular when fresh mortar or concrete properties have to be adjusted reliably, stabilising agents can be beneficially used to improve workability and robustness of the mixture. The mode of operation of these admixtures varies, rather affecting either the liquid phase or the solid particles in the dispersion, both causing strong interactions with the mortar or concrete system, and significant changes in their rheological behaviour. Furthermore, these are strongly affected by the environmental temperature during the casting process. In the paper the effect of temperature on the performance of stabilising agents in cementitious systems is presented and how performance changes affect fresh and hardening mortar or concrete properties. Particular attention is placed on interactions between stabilising agents and superplasticizers. Results are discussed with special focus on self-compacting concrete. KW - Biopolymers KW - Cementitious materials KW - Polycarboxylate ether KW - Rheology KW - Setting KW - Stabilising agent KW - Starch ether KW - Self-compacting concrete KW - Superplasticizer PY - 2011 U6 - https://doi.org/10.4028/www.scientific.net/KEM.466.97 SN - 1013-9826 VL - 466 SP - 97 EP - 104 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-22853 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Robustness improvement for Concrete at challenging climatic conditions T2 - Vorlesung im Rahmen des Kick-Off Meetings zum SPIN Projekt "Spearhead Network for Innovative, Clean and Safe Cement and Concrete Technologies" CY - Kigali, Rwanda DA - 2011-01-18 PY - 2011 AN - OPUS4-23183 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -