Effect of a Cationic Polymer on the Rheology of Cement Pastes Containing Na-Bentonite

This paper studies how a cationic polymer affects the rheological properties of cement pastes containing Na-bentonite in the presence of a polycarboxylate superplasticizer (PCE), and the fluidity was also investigated. The Herschel-Bulkley model was applied to fit the rheological data of cement pastes at the beginning and after 1 and 3 h. The results show that the cement pastes exhibit a significant increase in fluidity and turn to be a shear-thickening fluid with the addition of the cationic polymer KN, as indicated by the pseudoplastic index n. The yield stress and plastic viscosity of cement pastes containing Na-bentonite obviously decrease with the addition of KN. Statistical analysis was performed to evaluate the impact of KN and PCE on the rheological properties. PCE exhibits a significant influence on both yield stress and plastic viscosity, while KN also exerts an obvious effect on the yield stress for cement pastes containing minor amounts of PCE. The equations for yield stress and plastic viscosity are obtained, which will allow us to predict the yield stress and plastic viscosity of cement pastes containing various contents of PCE and KN.