TY - CONF A1 - Ünal, Murat A1 - Ramge, Peter A1 - Kühne, Hans-Carsten T1 - Restoration of dalles de verre concrete glass windows with polymer modified repair mortars N2 - On concrete glazings done in the so called ‘Dalles de Verre’ technique, damages occur frequently in form of cracks, Chips and corroded reinforcement Steel. These glazings, mostly dating back to the 20* Century, are often of art-historical importance. This article focuses on the analysis of occurring damages and their causes and on the development of special repair mortars and repair concepts for these glazings, which were done in a recent research project. On several reference buildings compressive strength, reinforcement location and diameter, carbonation depth as well as moisture and salt profiles were determined exemplarily. At the time of the concrete glass Windows’ construction generally no sufficient care was taken for an adequate concrete covering of the reinforcement. Carbonation-induced reinforcement corrosion is therefore the main cause of the occurring damage. Standards dealing specifically with the repair of Dalles de Verre do not exist. Therefore the polymer modified repair mortar was development according to the German guideline “Protection and Repair of Concrete Structures” (RL SIB, 2001). However due to the unique boundary conditions ofthe Dalles de Verre glazings, thespecifications of this guideline alone are not sufficient, they need to be altered and amended. In the article the individual requirements on repair mortars for different application tasks are described. Furthermore, the development of the mortars’ formulations and of a test specimen for performance tests under realistic conditions is shown. T2 - ASPIC 2012 - 7th Asian symposium on polymers in concrete CY - Istanbul, Turkey DA - 03.10.2012 KW - Rehabilitation of concrete structures KW - Polymer modified repair mortar KW - Special test specimens KW - Durability KW - Carbonation KW - Cultural heritage PY - 2012 SN - 978-975-561-427-4 SP - 397 EP - 404 AN - OPUS4-26774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ünal, Murat A1 - Kühne, Hans-Carsten A1 - Ramge, Peter T1 - Untersuchungen zur Schadenssituation an Betonglasfenstern und Entwicklung von Betonersatzsystemen zur Instandsetzung N2 - In den 50er Jahren des 20. Jahrhunderts entwickelten sich auch aufgrund kriegsbedingter Zerstörung von zahlreichen Gebäuden neue, experimentelle Formen in Kunst und Architektur. Insbesondere im Kirchenbau wurde besonderer Wert auf die Färb- und Lichtwirkung im Innenraum gelegt. In dieser künstlerischen Bewegung setzte sich auch aus Kostengründen die Idee der Betonverglasungen durch. Diese bestehen vorwiegend aus in Form gegossenen, geschlagenen oder geschnittenen Dickglasstücken, den sogenannten Dalles de Verre. Die Verbindung der einzelnen Elemente erfolgt nicht wie bei traditionellen Kirchenfenstern durch Bleiruten sondern durch Stahlbetoneinfassungen. Unterschieden werden dabei Betonverglasungen in Betonglasgusstechnik und in Formsteintechnik sowie Mischformen beider Techniken. Bedingt durch die Gestaltung der Betonverglasungen entstanden filigrane Bauteile mit geringen Betonüberdeckungen der Bewehrung. An diesen kunsthistorisch bedeutsamen Betonverglasungen treten daher gehäuft Schäden in Form von Rissen, Abplatzungen und korrodierter Bewehrung auf. Im Rahmen eines Forschungsvorhabens beschäftigte sich die BAM Bundesanstalt für Materialforschung und -prüfung mit der Analyse aktueller Schäden und Schadensursachen sowie der Entwicklung von geeigneten Instandsetzungskonzepten. Unter Beachtung sowohl technischer als auch kunsthistorischer Gesichtspunkte wurden Referenzobjekte zu genaueren Untersuchungen ausgewählt. Nach Rücksprache mit den zuständigen Denkmalschutzbehörden und Kirchengemeinden erfolgte eine Dokumentation der Bauwerks- und Schadenssituation der ausgewählten Referenzobjekte in Deutschland und dem europäischen Ausland. T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 12.09.2012 PY - 2012 SN - 978-3-00-034075-8 VL - 2 IS - 3.07 SP - 904 EP - 911 AN - OPUS4-26668 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ünal, Murat A1 - Kühne, Hans-Carsten ED - Alexander, M. G. ED - Beushausen, H.-D. ED - Dehn, F. ED - Moyo, P. T1 - Repair and restoration of 'Dalle de Verre' concrete windows N2 - On historically important concrete glazing damages occur frequently in form of cracks, chipping and corroded reinforcement. The present article focuses on the analysis of current damages and causes for damage and the development of repair concepts. The observation of compressive strength, carbonation depth, reinforcement layer and diameter as well as moisture and salt content profiles were determined on several reference objects. The carbonation-induced corrosion of the reinforcement was determined as the main cause of the present damage. The frequent occurrence of carbonation-induced corrosion is well-founded by the low concrete cover of the reinforcement. It is caused by the specific manufacturing process in the production of concrete-glass windows. Standards dealing especially with the repair of concrete glazing do not exist. Therefore appropriate repair and maintenance techniques in accordance with DIN EN 1504 and German guidelines for repair and protection of concrete (RL SIB 2001) were developed. The requirements for a repair mortar for these specific applications are described. Furthermore, the basics of cathodic corrosion protection with zinc are presented. T2 - 3rd International conference on concrete repair, rehabilitation and retrofitting III CY - Cape Town, South Africa DA - 03.09.2012 KW - Repair mortar KW - Concrete repair KW - Dalles de verre KW - Cultural heritage KW - Concrete glazing KW - Cathodic protection PY - 2012 SN - 978-0-415-89952-9 IS - Theme 2 SP - 607 EP - 612 PB - CRC Press CY - London, UK AN - OPUS4-26507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramge, Peter A1 - Kühne, Hans-Carsten ED - Alexander, M. G. ED - Beushausen, H.-D. ED - Dehn, F. ED - Moyo, P. T1 - Investigations on the performance of concrete repair mortars in composite specimen tests N2 - In the scope of a recent research project investigations on the performance of repair mortars for concrete structures were carried out at BAM. One of the key points of the project was the systematic investigation on the mode of action of single constituents and their interactions with Special emphasis on their influence on the mortars’ stiffness and shrinkage behaviour. The mortar’s shrinkage can be the reason of many following problems, which can be a direct result, i.e. the damage of the bond interface caused by constraining forces, or an indirect result, such as an increase in carbonation Depth or chloride penetration due to shrinkage induced constraining cracks, which will subsequently lead to durability problems. Especially when repairing weak Substrate concretes the proper adjustments of the mortar’s stiffness and shrinkage behaviour to the properties of the concrete is of essential importance for functionality and durability of the repair task. T2 - 3rd International conference on concrete repair, rehabilitation and retrofitting III CY - Cape Town, South Africa DA - 03.09.2012 KW - Concrete repair KW - Repair mortar KW - Composite specimen KW - Shrinkage KW - Stiffness KW - Constraining forces KW - Constraining cracks PY - 2012 SN - 978-0-415-89952-9 IS - Theme 3 SP - 1046 EP - 1052 PB - CRC Press CY - London, UK AN - OPUS4-26505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramge, Peter A1 - Kühne, Hans-Carsten A1 - Ünal, Murat T1 - Entwicklung modularer Steinersatzmassen für Instandsetzung und Reprofilierung von Naturstein im denkmalgeschützten Bereich N2 - Der größtmögliche Erhalt von Originalsubstanz ist das Ziel restauratorischer Maßnahmen, besonders an Denkmälern aus Naturstein. Der überwiegende Anteil der Restaurierungsarbeiten erfolgt in enger Abstimmung mit Denkmalpflegern. Die Objekte mit ihren speziellen Problemstellungen und Schadensbildern stellen höchste Ansprüche an den Restaurator im Hinblick auf die Instandsetzung. Aus technischer Sicht wäre oft eine Vierung, das heißt der Ersatz des beschädigten Steins durch ein neues Steinelement, die technisch zu bevorzugende Lösung. Bei Arbeiten im denkmalgeschützten Bereich sind Reprofilierungstechniken mit Steinersatzmassen jedoch eine sinnvolle Alternative, um möglichst wenig Originalsubstanz zu zerstören oder die Ausbesserung ggf. auch wieder entfernen zu können. T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 12.09.2012 KW - Instandsetzungsmörtel KW - Steinersatzmasse KW - Naturstein KW - Steininstandsetzung KW - Reprofilierung KW - Modulares System KW - Denkmalschutz PY - 2012 SN - 978-3-00-034075-8 VL - 2 IS - 3.07 SP - 2-1123 EP - 2-1130 AN - OPUS4-26548 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramge, Peter A1 - Kühne, Hans-Carsten ED - Alexander, M. G. ED - Beushausen, H.-D. ED - Dehn, F. ED - Moyo, P. T1 - Development of repair mortars for the restoration of natural stone in cultural heritage N2 - Compared with concrete repair, the repair of natural stone is generally a similar task but at the same time very different. For listed buildings and monuments, historical, cultural and aesthetical interests become the ruling parameters. Especially from the demands of total reversibility of repair measures and strict prevention of the slightest original substance loss, which are not known in concrete repair, various restrictions are derived. From an aesthetical point of view, the same appearance as the original stone is desired for the mortar, whereas from a technical point of view, a monolithic behaviour of the repaired stone with homogeneous material properties would be favoured. This creates a need for a multitude of different property combinations and the whish for an independent adjustability of technical and aesthetical properties. A research project dealing with the development and optimisation of modular Stone repair mortars is currently carried out at BAM Federal Institute for Materials Research and Testing. T2 - 3rd International conference on concrete repair, rehabilitation and retrofitting III CY - Cape Town, South Africa DA - 03.09.2012 KW - Repair mortar KW - Natural stone KW - Stone restoration KW - Stone reprofiling KW - Modular system KW - Cultural heritage PY - 2012 SN - 978-0-415-89952-9 IS - Theme 3 SP - 882 EP - 887 PB - CRC Press CY - London, UK AN - OPUS4-26506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramge, Peter A1 - Kühne, Hans-Carsten ED - Kusterle, W. T1 - Entwicklung und Modifikation von PCC- und SPCC-Mörteln für die Betoninstandsetzung T1 - Entwicklung und Modifikation von PCC- und SPCC-Mörteln für die Betoninstandsetzung T2 - Spritzbeton - Tagung 2012 CY - Alpbach, Tirol, Austria DA - 12.01.2012 PY - 2012 SP - 1 EP - 18 AN - OPUS4-25389 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ramge, Peter A1 - Ünal, Murat A1 - Kühne, Hans-Carsten T1 - Polymer modified repair mortars for the restoration of natural stone in cultural heritage N2 - A research project dealing with the development and optimisation of modular repair mortars for natural stone is currently carried out at the BAM (Federal Institute of Materials Research and Testing). To provide the conservator with the best possible options to match colour, texture and technical requirements of the stone, the repairmortar System will be Setup on a modular basis. Different binder Systems are planned, which can be combined with different aggregate compositions and different pigments. The aim is to be able to modify the appearance of the mortar independent of ist mechanical properties. When working in the ränge of cultural heritäge, one specific demand is the Option of total reversibility of each repair task. In order to guarantee the reversibility and to ensure that the repair mortar does by no means induce any Damage to the original substance (e.g. by constraining forces), strength and stiffhess of the repairmortar have to be controlled and kept below the respective values of the original natural stone. On the other hand the mortar needs a certain abrasion resistance and durability. To accomplish all these requirements the use of polymer dispersions is very helpful, as they allow the production of low stiffhess mortars with at the same time relatively high flexural strength values. Also investigations on “alternative” modifications known from historical applications such as the use of casein are carried out. T2 - ASPIC 2012 - 7th Asian symposium on polymers in concrete CY - Istanbul, Turkey DA - 03.10.2012 KW - Repair mortar KW - Natural stone KW - Cultural heritage KW - Polymer cement mortar (PCC) KW - Stone restoration KW - Stone reprofiling KW - Casein PY - 2012 SN - 978-975-561-427-4 SP - 415 EP - 422 AN - OPUS4-26775 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 - Gluth, Gregor A1 - Lehmann, Christian A1 - Haase, Oskar A1 - Rübner, Katrin A1 - Kühne, Hans-Carsten T1 - Geopolymerisation kieselsäurehaltiger Filterrückstände aus der Reststoffaufbereitung der Chlorsilanproduktion T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 2012-09-12 KW - Geopolymere KW - Reststoffe PY - 2012 SN - 978-3-00-034075-8 VL - 1 IS - 3.07 SP - 1-0517 - 1-0524 AN - OPUS4-26544 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Herbst, Tristan A1 - Gluth, Gregor A1 - Rübner, Katrin A1 - Kühne, Hans-Carsten T1 - SCM: living up to the standard N2 - European and Germany regulations demand an elaborate waste management to save natural resources, reduce waste volumes deposited at landfills and enhance sustainable development by recycling of various residues. Research into the use of these materials in the construction sector and other fields is a positive step forward in achieving these objectives. BAM shares its latest findings. PY - 2012 SN - 0959-6038 IS - September SP - 115 EP - 117 PB - Holbrook & Son CY - Dorking AN - OPUS4-30409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kühne, Hans-Carsten T1 - Instandsetzen von Rissen, Korrosion und Betonabtrag T2 - BMO-Fachtagung - Bauen mit Beton im Bestand und Betoninstandsetzung CY - Magdeburg, Germany DA - 2012-11-13 PY - 2012 AN - OPUS4-27298 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kühne, Hans-Carsten T1 - Instandsetzen von Rissen, Korrosion und Betonabtrag T2 - BAM-Fachtagung - Bauen mit Beton im Bestand und Betoninstandsetzung CY - Berlin, Germany DA - 2012-10-23 PY - 2012 AN - OPUS4-27294 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 - CONF A1 - Barthel, Maria A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Betontechnologische Ansätze zur Vermeidung innerstädtischer Hitzeinseln N2 - Die Versiegelung von Oberflächen, Bebauung und die Ausweitung städtischer Gebiete führen weltweit besonders in sonnenreichen Regionen zu innerstädtischen Hitzeinseln. Diese Flächen wirken als Wärmespeicher, so dass an Sonnentagen eine Temperaturdifferenz bis zu 10 K zwischen Stadt und umliegendem Land entstehen kann. Verstärkt wird dieser sogenannte Urban Heat Island Effect (UHIE) durch die meist direkte Abführung des anfallenden Regenwassers in die Kanalisation, wodurch eine Kühlung durch stetige Verdunstung unterbunden ist, Mit steigender Urbanisierung wächst auch die Bedeutung dieses Phänomens. Innerstädtische Hitzeinseln ziehen direkte wirtschaftliche und soziale Folgen nach sich, da hohe Temperaturen eine teure Klimatisierung der Städte bedingen. So entsteht ein erhöhter Verbrauch an Ressourcen sowie zusätzliche Abwärme. Das Wohlbefinden und die Gesundheit der Bevölkerung verschlechtern sich bei sehr hohen Temperaturen, was zu sinkender Leistungsfähigkeit und sogar zu einer erhöhten Sterberate führen kann. T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 12.09.2012 PY - 2012 SN - 978-3-00-034075-8 VL - 2 IS - 3.07 SP - 2-0042 EP - 2-0050 AN - OPUS4-26545 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Kühne, Hans-Carsten A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan T1 - SPIN - Spearhead Network for Innovative, Clean and Safe Cement and Concrete Technologies N2 - Globally, cement and concrete experts are at the cutting-edge to sustainable, green, healthy but nonetheless high-performance concrete. Today concrete is not yet well established in Africa, which offers 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 crosslinking research institutions and laboratories. It should not be neglected that concrete is a product with low transport ranges. This means that an improved concrete market mainly supports the local economy without exceeding financial drains to the international market. Thus it fosters the fight against poverty, which is an urgent need in most African countries. The project aims to cross-link experts with industry and policy making bodies, aiming to establish sustainable cement and concrete construction in Africa. KW - High-performance concrete KW - Cement technologies KW - Concrete technologies KW - Sustainable development PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-387428 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. SP - 1 EP - 3 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-38742 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten T1 - Optimising the rheology of concrete for sub-Saharan African boundary conditions / Optimierung der Rheologie von Beton für Rahmenbedingungen in Subsahara-Afrika N2 - Die Zement- und Betontechnologie in Afrika hat keine ähnlich lange Tradition wie viele Länder der nördlichen Hemisphäre. In vielen afrikanischen Ländern ist die Bauindustrie jedoch von Wachstum gekennzeichnet und hier werden Zement und Beton zukünftig zweifelsohne an Bedeutung gewinnen. KW - Africa KW - Cement KW - Concrete KW - Proficiency testing KW - Round robin PY - 2012 SN - 0373-4331 SN - 1865-6528 N1 - Sprachen: Deutsch/Englisch - Languages: German/English N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 78 IS - 09 SP - 60 EP - 67 PB - Bauverl. CY - Gütersloh AN - OPUS4-27338 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meinel, M. A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Betontechnologische Ansätze zur Erweiterung der Leistungsmerkmale von Betonpflastersteinen KW - Betonpflastersteine KW - Urban heat island effect PY - 2012 SN - 1439-7706 VL - 2 SP - 94 EP - 100 PB - ad-media-Verl. CY - Köln AN - OPUS4-27117 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - 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 N2 - Selbstverdichtender Beton (SVB) unterscheidet sich wesentlich von Normalbeton in der Höhe der Fließmitteldosierung. Die Funktionsweise von Fließmitteln auf Basis der für SVB üblichen Polycarboxylatether-Fließmittel (PCE) ist heutzutage in der bauchemischen Forschung sehr gut verstanden, allerdings dringt die Kenntnis über die Zusammenhänge nicht immer gleichermaßen umfangreich in die Praxis durch. Anders als frühere Fließmittelwirkgruppen, die auch heute noch einen wesentlichen Anteil am Fließmittelmarkt haben, sind PCEs äußerst vielgestaltig. Die Polymergeometrien können individuell auf die geforderten Leistungseigenschaften für bestimmte Anwendungen abgestimmt werden. Allerdings kann die Auswahl eines Fließmittels für spezifizierte rheologische Eigenschaften gleichsam den anschließenden Hydratationsprozess sehr stark beeinflussen. Der Ladungsdichte des verwendeten PCEs kommt dabei im Zusammenhang mit der Rheologie als auch der frühen Hydratation eine Schlüsselrolle zu. 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 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten ED - Alexander, M. G. ED - Beushausen, H.-D. ED - Dehn, F. ED - Moyo, P. T1 - Robustness improvement of fresh concrete and mortar performance for challenging casting environments with focus on sub-Saharan Africa N2 - For various concrete applications, the early properties are a major specification, determining the functioning, the mechanical properties, and the durability of structures. The rheological properties of cementitious systems are depending on the water-cement interaction as well as on interactions of chemical admixtures with the cement hydration. The cement hydration, however, is strongly affected by the environmental boundary conditions, such as the climate or the available equipment for the proportioning and dispersion of concrete. This paper presents strategies for the robustness improvement of fresh properties of cementitious systems for challenging and particularly warm climate conditions. After explaining the basic mechanisms affecting the workability, practical conclusions are drawn with special attention on the circumstances of sub-Saharan Africa, where the climatic conditions are difficult and the casting technology is often limited. Solutions are suggested, how despite the disadvantageous circumstances, highly elaborate engineered concrete and mortar can be applied safely and with consistent quality. T2 - 3rd International conference on concrete repair, rehabilitation and retrofitting III CY - Cape Town, South Africa DA - 03.09.2012 PY - 2012 SN - 978-0-415-89952-9 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. IS - Theme 4 SP - 1324 EP - 1329 PB - CRC Press CY - London, UK AN - OPUS4-26503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -