TY - CONF A1 - Schmidt, Wolfram A1 - Mota Gassó, Berta A1 - Sturm, Heinz A1 - Pauli, Jutta ED - Greim, M. ED - Kusterle, W. ED - Teubert, O. T1 - Influence of effects on nano and micro scale on the rheological performance of cement paste, mortar and concrete 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 such as self-compacting concrete. Today, admixture addition has become common practice in concrete technology, but the understanding of their highly complex mode of operation is extremely difficult and demands for understanding of processes within the range between nanometres and centimetres. 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. Methods are discussed that appear promising interdisciplinary tools for enhancement of the understanding of the relevant interactions that are responsible for the macroscopic flow of flowable concrete. T2 - 25. Workshop und Kolloquium Rheologische Messsungen an Baustoffen CY - Regensburg, Germany DA - 02.03.2016 KW - Rheology KW - Cement KW - Concrete KW - Superplasticizer KW - Nano scale PY - 2016 SN - 978-3-7345-1313-8 SP - 294 EP - 307 PB - tredition CY - Hamburg AN - OPUS4-36862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Weba, Luciana A1 - Silbernagl, Dorothee A1 - Mota Gassó, Berta A1 - Höhne, Patrick A1 - Sturm, Heinz A1 - Pauli, Jutta A1 - Resch-Genger, Ute A1 - Steinborn, Gabriele ED - Khayat, Kamal Henry T1 - Influences of nano effects on the flow phenomena of self-compacting concrete 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 such as selfcompacting concrete. 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. Methods are discussed that appear promising interdisciplinary tools for enhancement of the understanding of the relevant interactions that are responsible for the macroscopic flow of flowable concrete. T2 - 8th International RILEM Symposium on Self-Compacting Concrete CY - Washington, D.C., USA DA - 15.05.2016 KW - Adsorption KW - Analytics KW - Hydration KW - Polycarboxylate ether KW - Rheology PY - 2016 SP - 245 EP - 254 AN - OPUS4-36882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mota Gassó, Berta A1 - Schmidt, Wolfram A1 - Pauli, Jutta A1 - Sturm, Heinz T1 - Influences of hydration effects on the flow phenomena of concrete with admixtures N2 - Today, chemical admixtures like superplasticisers and stabilising agents are extremely important for modern concrete technology. These agents have meanwhile become common practice in concrete technology, but the understanding within the entire system lags far behind their application. The macroscopic rheology of concrete in the presence of superplasticizers strongly depends upon effects on a much smaller scale such as the hydration of the cement, the adsorption of superplasticizers, and the pore solution chemistry. T2 - 2nd International Conference on the Chemistry of Construction Materials CY - München, Germany DA - 10.10.2016 KW - Rheology KW - Cement KW - Superplasticiser PY - 2016 SN - 978-3-936028-96-6 VL - 50 SP - 276 EP - 279 PB - Gesellschaft Deutscher Chemiker e.V. CY - Frankfurt am Main AN - OPUS4-38849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Schmidt, Wolfram A1 - Ramirez Caro, Alejandra A1 - Sojref, Regine A1 - Mota Gassó, Berta ED - Greim, M. ED - Kusterle, W. ED - Teubert, O. T1 - Contribution of the coarse aggregates to rheology - effects of flow coefficient, particle size distribution, and volume fraction N2 - In order to observe the effect of the aggregate phases between 2 mm and 16 mm without overlap with rheological effects induced by the cement hy-dration and without interactions with a threshold fine sand particle size that affects both, paste and aggregates, rheological experiments were conducted on a limestone filler based paste mixed with aggregates up to 16 mm. Vari-ous aggregate fractions were blended and mixed with the replacement paste in different volumetric ratios. The dry aggregates’ flow coefficients were determined and compared to yield stress and plastic viscosity values at different aggregate volume fractions. The results indicated that the flow coefficient is not a suitable parameter to predict the performance of the aggregates in the paste. It was shown that the yield stress of pastes is largely determined by the blend of different aggregate fractions, while the plastic viscosity to large extend depends upon the coars-est aggregate fraction. Based on the results, ideal aggregate composition ranges for minimised yield stress are presented. For the plastic viscosity no such grading curves to achieve minimum values could be found, but high viscosity curves are identified. KW - Rheology KW - Flow Coefficient KW - Particle Size Distribution KW - Volume Fraction KW - Cement KW - Concrete KW - Reference Material KW - Limestone Filler PY - 2018 SN - 978-3-7469-1878-5 SP - 96 EP - 108 PB - tredition GmbH CY - Hamburg AN - OPUS4-44434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -