TY - CONF A1 - Schmidt, Wolfram T1 - "Effektivität von Stabilisierern - Einfluss des Feststoffvolumenanteils und Wechselwirkung mit Fließmitteln - "Effectiveness of Stabilising Agents - Influence of the Solid Volume Fraction and Interactions with Superplasticizers" T2 - 23. Konferenz "Rheologische Messungen an Baustoffen" CY - Regensburg, Germany DA - 2014-03-12 PY - 2014 AN - OPUS4-30832 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, J. T1 - A simple test method to assess the influence of pces in the rheology of flowable cementitious systems T2 - 1st International RILEM Conference on Rheology and Processing of Construction Materials and 7th RILEM Conference on Self-Compacting Concrete CY - Paris, France DA - 2013-09-02 PY - 2013 AN - OPUS4-29923 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 T1 - Agricultureal Waste for High Performance Construction - Potentials for Innovation, Markets, and Sustainability N2 - The presentation provides an overview of potentials for high performance construction materials based on local agricultural waste materials in different regions in Africa. T2 - 5th German-African Infrastructure Forum 2017 CY - Düsseldorf, Germany DA - 08.11.2017 KW - Cement KW - Concrete KW - Bio-based materials KW - Sustainability KW - Africa PY - 2017 AN - OPUS4-43545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Bio-adhesives and bio-chemicals from bio-mass N2 - After a brief introduction into past and modern concrete, the relevance of sustainable concrete technologies is emphasised from a global perspective. In order to minimise the environmental impact of cement and concrete in the world, solutions for alternative binder materials as well as rheology and performance modifying additives are presented based on local bio-based resources. However, the perception of bio-based constituents is typically rather negative in construction materials and its application is often limited to low-end construction. In order to show that this is not inevitable, the lecture ends with a number of case studies for the use of bio-based materials for high performance concrete applications. T2 - Sustainable Adhesives from Bio-Mass (SAB) Symposium CY - Greensboro, North Carolina, USA DA - 26.01.2017 KW - Starch KW - Bio-based materials KW - Superplasticizer KW - Ash KW - Concrete KW - Cement PY - 2017 AN - OPUS4-43544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Bio-based additives, resins and polymers roles and performances T2 - ICBBM Pre-Conference Seminar: Sustainable Bio-materials from Bio-mass for Use in Construction CY - Clermont-Ferrand, France DA - 2015-06-21 PY - 2015 AN - OPUS4-33561 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 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 - Tchetgnia Ngassam, Ines Leana A1 - Breitschaft, Gerhard A1 - Virchow, Stephen T1 - Challenges of the growing African cement market – Environmental issues, regulative framework and quality infrastructure requirements N2 - The African cement, concrete and construction business are growing at rapid pace. The cement sales are expected to grow tremendously until 2050. The number of newly built cement plants increases dramatically and in addition more cements are being imported from outside the continent, e.g. from Turkey, Pakistan, Indonesia, and China, driven by overcapacities in the countries of origin. This causes a high number of potentials and challenges at the same time. New cement plants can operate directly at best technological state of the art and thus incorporate more sustainable technologies as well as produce new and more sustainable products such as cements blended with sustainable supplementary cementitious materials such as calcined clays, and industrial or agricultural by products. At the same time the new variety of binding agent as well as the international imports, which are driven by price considerations, make the cement market prone to quality scatter. This puts pressure on the quality control regulations and institutions to ensure safety of construction, healthy application, and environmental safety for the population. The paper presents possible solutions to build up the rapidly increasing African cement production more sustainably than in the rest of the world as well as the related challenges and obstacles that need to be overcome. Based on experiences with a series of pan-African cement testing laboratory proficiency schemes conclusions are made on technical, regulative and political level. T2 - 2nd International Congress on Materials & Structural Stability CY - Rabat, Morocco DA - 21.11.2017 KW - Quality infrastructure KW - Round Robin KW - Proficiency testing KW - Cement KW - Africa PY - 2017 AN - OPUS4-43543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Concrete casting robustness improvement due to active rheology control N2 - With ongoing innovation in process technology, the challenges of concrete technology are more and more focused on the rheological optimisation for these processes, since improper mixture stability or poor compaction ability negatively affect the concrete homogeneity and quality. However, along with the increasing complexity of today’s concrete mixture compositions, concrete becomes more prone to failure regarding the casting process. Variable properties of the raw materials typically cause changing workability. The reasons can be found among others in scattering water contents, physical or chemical properties of the cement or varying environmental temperatures. Robustness in the delicately adjusted rheology, however, is of utmost importance for modern and future process technology, from sprayed concrete over pumpable concrete towards 3D-printing, with regard to the long-term strength, the function and the durability. Typically, material induced changes cannot be identified easily due to the complex interactions of concrete constituents. Therefore, a precise and prompt counteraction is impossible. However, it is known that the yield stress can be controlled by addition of supplementary superplasticizer or stabilising agent. In combination with computerized process observation tools that can rapidly interpret and react on changes in the rheology, it is therefore thinkable, that only these two admixture types can adjust the rheology steadily and permanently, regardless of the actual root cause for observed macroscopic rheology change. The presentation will firstly give a comprehensive overview of effects at the interface between pore solution, particles and hydrates, which affect the rheology of fresh concrete. Secondly, ways are recommended how the rheology can be actively manipulated before eventually computerized methods are demonstrated that help to actively and rapidly assess and counteract performance scatter during steady casting processes. T2 - 2nd International Congress on Materials & Structural Stability CY - Rabat, Morocco DA - 21.11.2017 KW - Rheology KW - Control charts KW - Cusum KW - Additive manufacturing KW - Online quality control PY - 2017 AN - OPUS4-43542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Controlling Rheology - The Key to Individual Concrete Performance Specifikations T2 - European Coatings Conference "Facade coatings and plasters" CY - Düsseldorf, Germany DA - 2013-10-29 PY - 2013 AN - OPUS4-29921 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Brouwers, J. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Correlation between setting, heat evolution, and deformations of cementitious binder systems depending on type and amount of superplasticizer T2 - XIII ICCC - International Congress on the Chemistry of Cement CY - Madrid, Spain DA - 2011-07-03 PY - 2011 AN - OPUS4-24019 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 - 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 - Tchetgnia Ngassam, Ines Leana A1 - Olonade, K. A. A1 - Mbugua, R. A1 - Kühne, Hans-Carsten T1 - Effects and potentials of plant based chemical admixtures on the performance of cementitious construction materials N2 - While today, engineers can choose from a wide range of rheology modifying admixtures, in some parts of the world, these are difficult to access, due to their complex processing. However, alternatives can be bio-based polymers such as polysaccharides from various sources. These are easily accessible all over the world, do not demand for complicated processing, and typically they are more sustainable than many established materials, which are crude oil-based. The paper presents the effects of acacia gum, cassava starch and the gum of triumfetta pendrata A. Rich on the rheological performance of cementitious systems. It is shown that acacia gum can be as efficient as polycarboxylate based superplasticisers, cassava starch can reduce the yield stress slightly with little effect on the plastic viscosity, and the gum of triumfetta pendrata A. Rich increases the thixotropy of cement pastes with plasticizing polymers significantly. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.03.2019 KW - Polysaccharides KW - Rheology KW - Cement KW - Chemical admixtures KW - Bio-based concrete PY - 2019 AN - OPUS4-47675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan A1 - Pirskawetz, Stephan T1 - Efficiency of high performance concrete types incorporating bio-materials like rice husk ashes, cassava starch, lignosulfonate and sisal fibres T2 - ICBBM - 1st International Conference on Bio-Based Building Materials CY - Clermont-Ferrand, France DA - 2015-06-21 PY - 2015 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-33559 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Eine einfache experimentelle Methode zur qualitativen Bewertung des Einflusses beliebiger Polycarboxylatether-Fließmittel auf die Rheologie/A rapid experimental method to qualitatively assess the influence of arbitrary polycarboxylate ether superplasticizers on the rheology T2 - 22. Kolloquium und Workshop "Rheologische Messungen an mineralischen Baustoffen" CY - Regensburg, Germany DA - 2013-03-06 PY - 2013 AN - OPUS4-29919 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Peters, Sarah A1 - Kühne, Hans-Carsten T1 - Einfluss der Partikelvolumenfraktion auf die Rheologie und die Effektivität von Polysaccharid-Stabilisierern in Gegenwart von Polycarboxylatether-Fließmitteln T2 - 19. Internationale Baustofftagung (ibausil) CY - Weimar DA - 2015-09-16 PY - 2015 AN - OPUS4-34499 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Einfluss der Polymerstruktur von Stabilisierern auf die Rheologie von selbstverdichtendem Beton und Mörtel T2 - 20. Kolloquium und Workshop "Rheologische Messungen an mineralischen Baustoffen" CY - Regensburg, Germany DA - 2011-03-01 PY - 2011 AN - OPUS4-23313 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Frisch- und Festbetonprüfungen - ausgewählte Hinweise aus der Prüfpraxis T2 - Fachtagung "Prüfen und Erhalten von Stahlbeton" CY - Berlin, Deutschland DA - 2014-10-09 PY - 2014 AN - OPUS4-31688 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 T1 - Influence of nano scale effects on the macroscopic rheology N2 - Chemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies. Meanwhile admixtures have become common practice in concrete technology, but the understanding of these highly complex polymers in the entire concrete system lags far behind their application. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamental mechanisms at the interface between particle or hydrate surfaces and the fluid phase at a very early stage of concrete formation, and links these effects to macroscopic flow phenomena. Based on the observations of the nano scale effects, it seems that higher sensitivity against variations in the constituents, the handling, or the boundary condition are the inevitable price for higher performances. However, eventually a very effective method is introduced that helps to maintain stable processes regardless of the root cause for performance changes based on an efficient in-situ process control scheme and superplasticizer and stabilising agents as counter actions. T2 - International Workshop on Nano-Engineered Meta-materials for Civil Infrastructures CY - Jinan, China DA - 20.5.2017 KW - Rheology KW - Meta materials KW - Nano engineering KW - Admixtures KW - Cement KW - Ettringite PY - 2017 AN - OPUS4-41032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -