TY - CONF A1 - Quercia, G. A1 - Spiesz, P. A1 - Hüsken, Götz A1 - Brouwers, H.J.H. T1 - Chloride intrusion and freeze-thaw resistance of self-compacting concrete with two different nano-SiO2 T2 - 18. Ibausil - Internationale Baustofftagung CY - Weimar, Germany DA - 2012-09-12 KW - Nano-SiO2 KW - Concrete KW - Self compacting KW - Durability KW - Chloride and freeze-thaw KW - Nano-silica PY - 2012 SN - 978-3-00-034075-8 VL - 2 IS - 3.07 SP - 2-0123 - 2-0136 AN - OPUS4-26542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quercia, G. A1 - Spiesz, P. A1 - Hüsken, Götz A1 - Brouwers, J. ED - Jacobsen, S. ED - Justnes, H. ED - Cepuritis, R. ED - Hornbostel, K. ED - Peng, Y. T1 - Effects of amorphous nano-silica additions on mechanical and durability performance of SCC mixtures N2 - 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. T2 - ICDC 2012 - International congress on durability of concrete CY - Trondheim, Norway DA - 2012-06-18 KW - Nano-silica KW - Concrete KW - Self Compacting KW - Durability KW - Chloride and Freeze-thaw PY - 2012 SN - 978-82-8208-031-6 SP - A2-4, 1-15 AN - OPUS4-30540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quercia, G. A1 - Hüsken, Götz A1 - Brouwers, H.J.H. T1 - Effect of olivine nano-silica additions on the fresh and hardened behaviour of cement pastes and mortars N2 - The high demand for sustainable and durable building materials requires profound knowledge on the material properties. In this respect, the phenomena occurring at nano-level are of crucial importance for the design of new building materials. Therefore, all around the world, increasing amounts of funding are being directed to research projects dealing with material properties on nano-level, which is claimed to have tremendous potential for the future. One of the most referred to and used cementitious nano-material is amorphous silica with a particle size in the nano-range, even though its application and effects on concrete have not been fully understood yet. Olivine (Mg,Fe)2Si04 is the fastest weathering siiicate mineral dissolving easily in acid. Düring dissolution in acid the metallic ions (Mg2+,Fe2+) are replaced by H+, yielding Si(OH)4 monomers and metallic ions in solution. After cleaning treatments an amorphous nano-silica is obtained. The produced olivine nano-silica (OnS) has a specific surface area between 100 and 400 m2/g, the size of the primary particles, which are agglomerated in Clusters, ranges from 10 to 25 nm and the impurity content is below 5 % IV. Literature related with the application of OnS in cement based materials is scarce; only one research work performed by Justnes and Ostnor 121 is available. Thus, the effect of adding OnS in cement based Systems has been not studied. Based on this, the present research aims on elucidating the effects of OnS in the fresh and hardened state of cement pastes and mortars. T2 - 1st International conference on the chemistry of construction materials CY - Berlin, Germany DA - 07.10.2013 KW - Nano-silica KW - Self compacting concrete KW - Durability KW - Chloride KW - Freeze-thaw PY - 2013 SN - 978-3-936028-75-1 SP - 179 EP - 182 AN - OPUS4-30410 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -