Title: Influence of Adsorbing Polymers on the Macroscopic Viscosity of Concentrated Cement Pastes

Author(s): Julie Hot and Nicolas Roussel

Publication: Symposium Paper

Volume: 288

Issue:

Appears on pages(s): 1-11

Keywords: adsorption, direct contacts, superplasticizers, viscosity, yield stress.

DOI: 10.14359/51684231

Date: 9/14/2012

Abstract:
Superplasticizers (SP) are expected to affect cement particles colloidal interac¬tions network and yield stress. They can therefore affect apparent viscosity which depends both on yield stress and viscous dissipation. However, at high shear rates at which colloidal interactions can be neglected, cement pastes viscosity is expected to only depend on hydro¬dynamic energy dissipation in the interstitial fluid and shall not be affected by SP. Experi¬mental results show, however, that it is not the case, and that SP also affects the contribu¬tion of hydrodynamic energy dissipation to macroscopic viscosity of cement paste. The rheological and adsorption measurements presented in this work suggest that this peculiar effect can be attributed to the influence of direct contacts between cement particles on viscosity. The polymer adsorbed on cement grains seems to be able to decrease the friction coefficient between cement grains, and therefore, decrease the macroscopic viscosity of the mixture.