Rheological Properties of Silica Beads in the Presence of Different Polymers and Electrolyte

Abstract

Properties of interstitial liquid phase in cement paste, including the species and concentrations of polymers and ion etc., play an important role for the rheological properties of cementitious materials. In order to better understand their effect, an inert model substance, spherical silica beads (SBs) with defined surface and granulometry were used in the presence of electrolytes (CaCl2) and/or different polymers, including polycarboxylate superplasticizer (PCE) and polyethylene glycol (PEG). It was found the presence of Ca2+ greatly increases the viscosity and yield stress of silica beads paste (SBP), which is proportional to the [Ca2+]. For the effect of PCE, the addition of PCE is beneficial to the flowability of SBP, but a high dosage of PCE leads to a reversal effect. Furthermore, the yield stress firstly increases and then decreases with increasing [Ca2+] under the same dosage of PCE. The addition of PEG always increases the yield stress of SBP, regardless of the ion concentration and the presence or not of PCE.