Nonshrinking cement pastes were tested in a coaxial-cylinder viscometer, and the effect of the test regime on the shape of the flow curve was studied. Using a short cycle time, the effects of prolonged mixing age and water/cement ratio on the measured rheological parameters were studied. Experiments at constant shear rate were performed to study the breakdown of the structure. The amount of bound water was determined by thermogravimetry. The rheology of nonshrinking cement pastes is broadly similar to that of ordinary Portland cement pastes. However, the rapid formation of ettringite, combined with a slight increase in specific surface area, increases the yield value and plastic viscosity. Prolonged mixing results in accelerated formation of ettringite and consequent stiffening of the paste, which is also associated with reduced expansion in service. Structural breakdown takes place under continuous shear, and the change can be explained by the effect of shear on the amount of water bound in the ettringite crystals.
|Translated title of the contribution||Rheology of nonshrinking cement pastes|
|Number of pages||16|
|Journal||Archiwum Inżynierii La̢dowej|
|Publication status||Published - 1988|
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