Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Microstructure of cementitious binders with silica fume
Condensed silica fume (SF) is spherical particles of much smaller average size (about 0.15 pm) than ordinary Portland cement grains (about 10 gm). Thus, they will easily pack in the cavities formed between irregular grains or between cement grain and aggregate interface. This initial physical effect is beneficial to obtain concrete with low w/cm and with an improved rheology when plasticisers are used. The initial pore refinement leads to less permeability immediately after setting. SF is a very active pozzolana even at low w/cm under sealed curing conditions. At such curing conditions the cement hydration may halt due to self-desiccation, but unreacted cement grains as microaggregates are not negative for the strength. The CSH gel formed in the pozzolanic reaction are of similar nature as the one produced directly from cement hydration, but the average length of the polysilicate anions is longer and the Ca/Si ratio is lower. These two CSH types may co-exist in the binder. The CSHgel from the pozzolanic reaction is of hydraulic nature and exhibits high strength.
Microstructure of cementitious binders with silica fume
Condensed silica fume (SF) is spherical particles of much smaller average size (about 0.15 pm) than ordinary Portland cement grains (about 10 gm). Thus, they will easily pack in the cavities formed between irregular grains or between cement grain and aggregate interface. This initial physical effect is beneficial to obtain concrete with low w/cm and with an improved rheology when plasticisers are used. The initial pore refinement leads to less permeability immediately after setting. SF is a very active pozzolana even at low w/cm under sealed curing conditions. At such curing conditions the cement hydration may halt due to self-desiccation, but unreacted cement grains as microaggregates are not negative for the strength. The CSH gel formed in the pozzolanic reaction are of similar nature as the one produced directly from cement hydration, but the average length of the polysilicate anions is longer and the Ca/Si ratio is lower. These two CSH types may co-exist in the binder. The CSHgel from the pozzolanic reaction is of hydraulic nature and exhibits high strength.
Microstructure of cementitious binders with silica fume
Mikrostruktur von Zementbinder mit Mikrosilica
Justnes, H. (Autor:in)
2002
8 Seiten, 10 Bilder, 13 Quellen
Aufsatz (Konferenz)
Englisch
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