Spolupůsobení cementu a superplastifikačních přísad z pohledu reologického chování cementové pasty

The interaction between cement and superplasticizirs from the point of cement rheology

conference paper

Czech

Clanek podova prehled o poznatcich k pusobeni superplastifikatoru na bazi polykarboxylatu a naftalensulfonatu. Dale jsou v clanku uvedeny vysledky experimentalni prace zabyvajici se vlivem siranu draselneho na disperzni pusobeni techto prisad.

The first part of this paper is a summary of the actual state of knowledge about the effectiveness of poly-carboxylic poly-ether superplasticizers (PCE) and naphthalene sulphonate-formaldehyde condensate (NSF) on cement hydration. The second part shows results of experimental work on the rheological behaviour of cement pastes in dependence on the dosage of three different superplasticizers: two structurally different PCEs and one NSF. A portland cement CEM I 52,5 R with a low content of dissolvable alkalies was used for investigation. A definite amount of potassium sulphate was added with the mixing water, in order to create a cement with a high alkali content. Changes in the rheological behaviour of the cement pastes with and without the addition of potassium sulphate depending on the dosage of several superplasticizers were determinated by measuring the torque (viscometer VISKOMAT NT). In addition to the time dependant variation of the torque at constant shear rate the measurements for determinantion of the saturation point of the superplasticizers were carried out. The results show, that there are differences in the rheological behaviour of cement pastes depending on the structure of superplasticizers and also that alkali content influences the plasticizing effect especially for polycarboxylates.

rheology, superplasticizers

KUČEROVÁ, H., RÖSSLER, C.

5. 2. 2004

FAST VUT v Brně

Brno

80-214-2560-1

Juniorstav 2004

x

1