Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Some aspects of cement chemistry regarding selfcompacting concrete (SCC)
The rheological behaviour of SCC during the very first hours of hydration is influenced by the formation of syngenite and ettringite. The probability of phase formations was determined by thermodynamic calculations. Depending on alkali- and sulfate content of the liquid phase, syngenite and ettringite are formed with different morphology during the initial stage of hydration by which the rheological behaviour of the SCC is influenced. The frequently used superfine materials powdered limestone and fly ash are not to interpret as inert fillers. Depending on fineness, powdered limestone acts as nucleation site for C-S-H and consequently it accelerates in the early stage of hydration the reaction of C3S. Because of that, the usually observed retarding effect of superplasticisers based on polycarboxylatethers is partially compensated. Fly ash reacts considerably slow and reaches within SCC-binders only a hydration degree of approximately 10 % after 3 month. Testing procedures for durability must consider this by appropriate defining of the testing age of the SCC.
Some aspects of cement chemistry regarding selfcompacting concrete (SCC)
The rheological behaviour of SCC during the very first hours of hydration is influenced by the formation of syngenite and ettringite. The probability of phase formations was determined by thermodynamic calculations. Depending on alkali- and sulfate content of the liquid phase, syngenite and ettringite are formed with different morphology during the initial stage of hydration by which the rheological behaviour of the SCC is influenced. The frequently used superfine materials powdered limestone and fly ash are not to interpret as inert fillers. Depending on fineness, powdered limestone acts as nucleation site for C-S-H and consequently it accelerates in the early stage of hydration the reaction of C3S. Because of that, the usually observed retarding effect of superplasticisers based on polycarboxylatethers is partially compensated. Fly ash reacts considerably slow and reaches within SCC-binders only a hydration degree of approximately 10 % after 3 month. Testing procedures for durability must consider this by appropriate defining of the testing age of the SCC.
Some aspects of cement chemistry regarding selfcompacting concrete (SCC)
Stark, Jochen (Autor:in) / Friebert, Marco (Autor:in)
2005
8 Seiten, 9 Bilder, 2 Tabellen, 6 Quellen
Aufsatz (Konferenz)
Englisch
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