Thixotropy-Dependent Form Filling Ability of Cement Paste

The form filling ability of fresh concrete is not only dependent on its rheological parameters yield stress and viscosity but on thixotropy as well. Currently, there are not many investigations regarding the effect of thixotropic structural build up on the form filling behaviour of concretes. The thixotropy of fresh concrete is mainly dependent on the thixotropic character of its cementitious paste. Thus, form filling experiments on cementitious suspensions were performed investigating their workability in dependence of their rheological parameters as preliminary tests for the workability prediction of fresh concretes. For this reason, cementitious pastes with equal solid content but varying yield stress and thixotropy were tested. Rotational rheometer measurements to investigate the rheological key parameters yield stress, viscosity and thixotropy were combined with formfilling tests in a L-shaped model formwork. With increasing thixotropy, flow distance in the formwork and thus form filling ability of the cementitious suspensions decreased. The conducted experimental series therefore is the base to enhance the prediction of form filling behaviour of fresh concrete.