Effect of Superplasticizers on Apparent Viscosity of Cement-Based Material with a Low Water-Binder Ratio

The presence of a superplasticizer can significantly impact the apparent viscosity of cementitious material. However, its working mechanism remains controversial. In this paper, the effect of different polycarboxylate-based superplasticizers (SPs) on the viscosity of low water-binder ratio cementitious materials was characterized by V-funnel efflux time and rheological parameters. The results show that superplasticizer based on the copolymerization of acrylic acid and polyethylene glycol monoallyl ether shows a better performance compared to the two other types of SPs according to the V-funnel efflux time and apparent viscosity of cementitious materials. Furthermore, it is found that, for a same slump flow value, the apparent viscosity of mortars with different SPs is related to the water film thickness of cement particles, and more closely to the viscosity of aqueous solutions containing unabsorbed SPs.