Cellulose ethers and water retention
Résumé
We first study in this paper the viscosity enhancing effect of cellulose ethers (CE) in aqueous solutions and its evolution around the so-called overlapping concentration. We show that, within the range of typical industrial dosages, the rheological behavior of CE solutions is only slightly affected by the pH and type of ions found in a typical cement paste. Moreover, our rheology, dynamic light scattering and water retention measurements suggest that, below the overlapping concentration, water retention can be seen as a purely biphasic filtration process, during which the rheological properties of the interstitial solution dictate the ability of water to resist migration under a pressure gradient. Above the overlapping concentration, water retention results from polymer coil associates, which can get jammed between cement grains.