The influence of mixing on the rheology of fresh cement paste

Abstract The influence of mixing shear rate on the rheological properties of cement paste was investigated. Cement pastes were mixed, sheared at a constant rate in a rheometer, and then subjected to increasing and decreasing shear rates, producing a hysteresis loop when plotted against shear stress. The extent of structural breakdown within the paste was evaluated as a function of mixer type and speed, based on hysteresis loop area. Plastic viscosity was measured using the linear portion of the hysteresis loop down curve. Well-mixed pastes exhibited a decreased propensity for further structural breakdown and a low plastic viscosity. Paste removed from a no-fines concrete had rheological properties similar to paste mixed at moderate speeds in a high shear blender