SCC flow curves from vane geometry rheometer
Résumé
The objective of the present study is to show how recording the changes in the rotation torque according to the rotation speed can lead to identifying a characteristic flow curve for the tested concrete. The concrete rheometer used for the study is composed of a vane tool. The rotation speed of the tool is imposed and the resulting torques are measured. The experimental rotation protocol used in this study corresponds to a rapid speed increase followed by a steady speed then the rotation speed slows down. The evolution of the torque measured as the rotation speed decrease (restructuring phase) is considered as being a succession of stationary states. By considering the fluid equivalent to a Bingham fluid for which the yield stress has already been identified and by using an analogy with a coaxial-cylinders rheometer, relevant relationships between the rotation speed of the vane and the rate of shearing along the tool are identified. Shear stress and shear rate calculations for each value of torque and rotation speed lead to the complete flow curve of the tested fluid. The data treatment method is adjusted to accurately evaluate the parameter linked to the flow stop in the case of a non-nil shear rate when the yield stress is reached. The comparison of the characteristic rheological parameters of SCC obtained from the rheometer and both spreading and V-Funnel tests indicate very satisfactory correlations.
Domaines
Génie civil
Origine : Fichiers produits par l'(les) auteur(s)
Loading...