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 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 - 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 - 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 - 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 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 -