Abstract The effects of different sulfates on fluidity, yield stress, and apparent viscosity of cement paste with polycarboxylate-type superplasticizer were investigated. The results showed that sulfates with alkali ions (such as Na2SO4 and K2SO4) had a pronounced negative effect on the dispersity of PC superplasticizer, while the effect of indissolvable sulfate (such as CaSO4·2H2O) on the dispersity of PC superplasticizer was slight. The mechanism of sulfates on dispersibility of polycarboxylate superplasticizer was analyzed through zeta potential and equilibrium adsorption capacity. It was indicated that with the increase of dissolution rate and dissolution speed, and under the effects of alkali ions, the competitive adsorption between sulfate ions and polycarboxylate superplasticizer was enhanced, the absolute value of zeta potential decreased as double electrode layer was destroyed, the aggregation behavior of PC superplasticizer was boosted with larger aggregation size, and the calcium ion concentration in the interstitial solution was generated. In this way, the electrostatic repulsion of cement particles was weakened; the flocculation structure became more and stronger. Under certain shearing rate, less degree of flocculation structure was damaged, which meant the decrease of fluidity and rheological properties in cement paste.
Effect and mechanism of sulfates on dispersity of polycarboxylate-type superplasticizers
KSCE Journal of Civil Engineering ; 21 , 6 ; 2195-2201
2016-10-25
7 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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