Rheological properties of cement pastes incorporating polycarboxylate superplasticizers containing different hydrophobic groups

Rheological properties of cement pastes with polycarboxylate superplasticizers (PCE) containing different hydrophobic groups (styrene, n-butyl acrylate units) at different water to cement ratios (w/c) were investigated. Further investigation on the solution behavior (hydrodynamic radius, solution viscosity) and adsorption behavior revealed the fundamental difference of these PCE samples. At high w/c, the rheological properties of cement pastes primarily depended on the ALT and the differences at constant flow diameter were small. At low w/c, the yield stress primarily depended on the ALT, while the apparent viscosity difference relied on the balance of ALT and solution viscosity. The styrene unit enhanced the backbone stiffness and therefore the adsorption affinity, intrinsic viscosity, yet smaller ALT, therefore reduced the apparent viscosity at a proper dosage. The n-butyl acrylate unit always increased the apparent viscosity of cement pastes.