Influence of superplasticizer on the non-Newtonian characteristics of cement paste

The superplasticized cement paste usually exhibits non-Newtonian characteristics, which depend on the type of superplasticizer and its dosage. Current attempts in the cement paste rheology literature have mainly focused on reducing the data from steady shear experiments to simple constitutive models, and exploring the influence of superplasticizer dosage and type based on these model parameters. In this study, the non-Newtonian behavior of the cement paste is characterized based on more fundamental experimental investigations without recourse to any specific model. Steady shear, creep and recovery, and stress relaxation experiments were conducted on a variety of superplasticizer and cement paste combinations, and the transition from non-linear viscoelastic to non-Newtonian and subsequently to linearly viscous fluid, as the dosage is increased were observed. Additionally, Marsh cone experiments were conducted to determine the optimum dosages and it was found that dosages determined based on Marsh cone were close to the dosages at the transition to the linearly viscous behaviour.