Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-22126 Beitrag zu einem Sammelband Schmidt, Wolfram; Brouwers, J.; Kühne, Hans-Carsten; Meng, Birgit Khayat, K. H.; Feys, D. Effects of superplasticizer and viscosity-modifying agent on fresh concrete performance of SCC at varied ambient temperatures Varying ambient temperatures in plants or on construction sites during casting of SCC can cause serious problems affecting the fresh concrete performances, such as rheological properties and setting time, with consequences for the hardened properties in the structure. By sensible choices of the components, the robustness of SCC mixtures against temperature variations can be improved. However, this aspect has not been the focus of intensive research yet. In this study the effects of varied ambient temperatures on the early performance of differently composed SCC mixtures are investigated, with emphasis on changes in rheology, early deformations, heat evolution and setting. Focus is placed on the study of the influence of the polycarboxylate ether molecule type as well as different viscositymodifying agents on the temperature robustness. Effects on the relevance for practical concrete applications are evaluated, which will provide a reliable framework of possible actions on the appropriate use of admixtures for SCC. Springer RILEM 2010 SCC 2010 - 6th International RILEM Symposium on self-compacting concrete / 4th North American conference on the design and use of SCC - Desgin, Production and Placement of self-consolidating concrete (Proceedings) 1 978-90-481-9663-0 SCC 2010 - 6th International RILEM Symposium on self-compacting concrete / 4th North American conference on the design and use of SCC - Desgin, Production and Placement of self-consolidating concrete Montreal, Canada 2010-09-26 2010-09-29 2 65 77 10.1007/978-90-481-9664-7_6 2016-02-19 OPUS4-30540 Beitrag zu einem Tagungsband Quercia, G.; Spiesz, P.; Hüsken, Götz; Brouwers, J. Jacobsen, S.; Justnes, H.; Cepuritis, R.; Hornbostel, K.; Peng, Y. Effects of amorphous nano-silica additions on mechanical and durability performance of SCC mixtures In the recent years the application of nanotechnology in building materials has increased exponentially. One of the most referred and used nano-materials is amorphous silica with particles size in the nano-range, even though its application and effect in concrete has not been fully understood yet. It has been reported that nano-silica (nS) addition increases the compressive strength and reduces the overall permeability of hardened concrete due to the pozzolanic properties which are resulting in finer hydrated phases (C-S-H gel) and densified microstructure (nano-filler and anti leaching effects). These effects enhance the durability of concrete structures such as bridges, quays or off-shore oil facilities in marine environments. In this study two different types of nano-silica were applied in self-compacting concrete (SCC), both having similar particle size distributions (PSD) but produced in two different processes (fumed powder silica and precipitated silica in colloidal suspension). The influence of nanosilica on SCC was investigated with respect to the properties of concrete in the fresh state (workability) and hardened state (mechanical properties and durability). Additionally, the densification of microstructure of the hardened concrete was verified by SEM and EDS analyses. The obtained results demonstrate that an efficient use of nano-silica in SCC can improve its mechanical properties and durability. Considering the reactivity of the two nano-silica studied, colloidal type shown more reactivity at early age, which influenced all the final SCC properties. 2012 ICDC 2012 - 1st International congress on durability of concrete (Proceedings) 978-82-8208-031-6 ICDC 2012 - International congress on durability of concrete Trondheim, Norway 2012-06-18 2012-06-21 A2-4, 1-15 2016-02-20