TY - CONF A1 - Leinitz, Sarah A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Assessment of rheological effects in the binder on the rheology of mortar and concrete N2 - In the last years flowable concrete has become increasingly important in applications such as, for systems with highly reinforced concrete with a complicated formwork, or sprayed concrete and 3D-printing of concrete. For all these applications it is necessary to have tailored rheological properties. Rheology can be described by values of yield stress and plastic viscosity, which can be determined for example by evaluation of rheometer measurements. But for different materials various rheometers with different geometries and stirrers are being used. To see the effects from paste in concrete, it is necessary to investigate mixes of paste, mortar and concrete, stepwise. But currently there exists no device, which is calibrated for these different systems at once. Due to this fact, conventional tests such as V-funnel efflux-time and flow diameter were determined, as well as rheometer data in different cell sizes and geometries. In this study the assessment of rheological effects in the binder on the rheology of mortar and concrete was investigated by using combination of two rheometers. T2 - Rheologische Messungen an Baustoffen 2018, 27. Workshop und Kolloquium CY - Regensburg, Germany DA - 07.03.2018 KW - Rheology KW - Cement KW - Mortar KW - Upscaling KW - Superplasticizer PY - 2018 SN - 978-3-7469-1878-5 VL - 27 SP - 109 EP - 111 PB - tredition GmbH AN - OPUS4-44444 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Mota, Berta A1 - Leinitz, Sarah A1 - Kühne, Hans-Carsten A1 - Rogge, Andreas T1 - The effect of superplasticizers on rheology and early hydration kinetics of rice husk ash-blended cementitious systems N2 - Superplasticizers (SPs) have been employed in concrete technology for decades to improve the workability of concrete in its fresh state. The addition of SPs in cement-based systems affects the early properties. Although the interaction of the cement particles with various SPs has been extensively researched, there still exists limited research on the interaction of SPs with supplementary cementitious materials such as rice husk ash (RHA). This paper investigates the rheological properties and early hydration kinetics of RHA-blended systems with three types of SPs, a polycarboxylate ether (PCE) and two lignosulphonates (LS-acc and LS-ret). In rheological properties, the addition of SP causes an initial improvement of workability as the yield stress is significantly reduced. The pastes with PCE and LS-acc show a slight increase of yield stress over time whereas pastes with LS-ret tend to lower the yield stress slightly over time, further improving the workability. Without SP, pastes with RHA show a lower yield stress but an increase in plastic viscosity as cement is further replaced with RHA. The addition of the LS SPs is observed to lower the plastic viscosity but remains constant with further replacement of cement with RHA. This indicates that LS SPs further adsorbs on RHA particles and hydration products produced causing dispersion of the particles within the system. In early hydration kinetics, pastes with PCE retard hydration and the degree of retardation is further increased with LS SPs. In the presence of RHA, the retardation of LS SP systems is significantly reduced. The pastes with PCE show more ettringite in the SEM micrographs, but is observed to be shorter needles. This indicates an initial good workability for PCE. However, C-S-H and CH were observed to be low in quantity, whereby the pastes with LS show more nucleation sites for C-S-H and CH. The ettringite needles in the LS systems were similar in quantity and more elongated in some cases but not abundant as in the PCE systems. KW - Plastic viscosity KW - Cement KW - CO2 reduction KW - Supplementary cementitious materials KW - Rice husk ash KW - Superplasticizers KW - Hydration KW - Rheology KW - Yield stress KW - Slump flow PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0950061817310978?via%3Dihub U6 - https://doi.org/10.1016/j.conbuildmat.2017.05.197 SN - 0950-0618 SN - 1879-0526 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 150 SP - 511 EP - 519 PB - Elsevier Ltd. AN - OPUS4-41036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leinitz, Sarah A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten ED - Priebe, Nsesheye Susan T1 - Influence of stabilising agents on limestone filler and cement pastes N2 - The paper showed that the STA behave completely different in pastes with LSF and cement, respectively, as well as with or without PCE. While STA can affect plastic viscosity and yield stress in LSF and cement pastes, the addition of PCE causes that the STA have mainly an impact on plastic viscosity, except DGUM and ST-low. The performance of STA in LSF and cementitious systems can vary greatly due to different ionic strengths of the liquid phase. The charges due to modification of the starches have an intense influence on the rheological properties in pastes. The combined use of PCE and STA can lead to a significant increase of the plastic viscosity without a strong effect to the yield stress. For the evaluation of the effectivity of STA the ionic strength of the liquid phase and the solid volume fraction of the binder have to be taken into account. Further influences can arise from grain size and aggregate content as well as the temperature, which were not discussed in this paper. T2 - 3rd Symposium on Knowledge Exchange for Young Scientists (KEYS) CY - Johannesburg, South Africa DA - 26.06.2017 KW - Stabilising agent KW - Limestone filler KW - Cement PY - 2017 SN - 978-3-9818270-7-1 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 3 SP - 143 EP - 146 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-41000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Z. C. A1 - Haist, M. A1 - Ivanov, D. A1 - Jakob, C. A1 - Jansen, D. A1 - Schmid, M. A1 - Kißling, P. A. A1 - Leinitz, Sarah A1 - Link, J. A1 - Mechtcherine, V. A1 - Neubauer, J. A1 - Plank, J. A1 - Schmidt, Wolfram A1 - Schilde, C. A1 - Schröfl, C. A1 - Sowoidnich, T. A1 - Stephan, D. T1 - Characterization data of reference cement CEM III/A 42.5N used for priority program DFG SPP 2005 "Opus Fluidum Futurum - Rheology of reactive, multiscale, multiphase construction materials" N2 - Two types of cements were selected as the reference cement in the priority program 2005 of the German Research Foundation (DFG SPP 2005). A thorough characterization of CEM I 42.5 R has been made in a recent publication. In this paper, the characterization data of the other reference cement CEM III/A 42.5 N are presented from the aspects of chemical and mineralogical compositions as well as physical and chemical properties. The characterization data of the slag, which is the second main constituent of this specific cement besides the clinker, are presented independently. For all data received, the mean values and the corresponding errors were calculated. The data shall be used for the ongoing research within the priority program. Also, researchers from outside this priority program can benefit from these data if the same materials are used. KW - Cement KW - Slag KW - Characterization KW - DFG SPP 2005 PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-568980 SN - 2352-3409 VL - 30 SP - 1 EP - 14 PB - Elsevier CY - Amsterdam AN - OPUS4-56898 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -