Rheological and flow characteristics of fresh concrete in the rotational rheometer

The coaxial cylinder rheometer is widely used to measure the torque and rotational speed (T-N) of fresh concrete. T-N can be transformed into the corresponding rheological parameters via the solution of the ‘Couette inverse problem’. However, the solution of the ‘Couette inverse problem’ is a theoretical solution, which may produce errors due to the complex geometric shape of the coaxial cylindrical rheometer and the possible plug or secondary flow. The purpose of this study is to investigate the rheological and flow behaviors of fresh concrete in the rotational rheometer by coupling CFD (Computational Fluid Dynamics) simulations and experiments. The efficient high-fidelity 3-D CFD simulations of fresh concrete flowing in the ConTec Viscometer 5 are conducted using the Reynolds Average Navier–Stokes (RANS) model with the Multi-Reference Frame (MRF). Both Bingham and Herschel–Bulkley (H–B) models are adopted, and the numerical simulations are validated against by experiments, which enhanced the confidence that RANS simulation with MRF could supplement the experiments and elucidate the rheological and flow behaviors of fresh concrete with the whole-flow domain information.