PERTURBATION PATTERNS AND VELOCITY MODELLING OF A FRESH CONCRETE AROUND A SPHERICAL PROBE VISCOPROBE? IMMERSED IN CONCRETE MIXERS

摘要

Viscoprobe? is a system made of a spherical probe and a software, intended to deduce inline some rheological parameters of a fresh concrete, during the elaboration process. The software analyses a strength signal, assuming the Stokes's law. In the industrial practice, the analysis is efficient for sufficient fluid concrete as self compacting concrete [1]. In the present paper, the velocity field induced in two concrete mixers is analysed using numerical simulations, in order to assess the use of the Stokes's law for such complex non-Newtonian flows. The perturbation patterns created by the presence of a probe are analysed, first by exhibiting the influence of the probe on the global flow, then by displaying the influence of the blades on the local flow due to the probe alone. It is shown that, among the hypothesis of the Stokes's law, assuming that the fluid is at rest at infinity appears to be relevant in the studied cases. Also, the analysis reveals that concrete with higher Bingham behaviour requires more complex drag force estimation, including non-Newtonian rheology effect.