Numerical simulations of fresh concrete flow in the L-Box test using CFD

Concrete remains a widely used material in construction. As structures become more optimized, a deeper understanding of the rheology of the concrete mixture is necessary. This paper aims to numerically simulate the flow of fresh concrete in the L-box apparatus, with the objective of gaining insights into its rheological behavior and predicting its properties. The fresh concrete flowing through the L-Box test is simulated from the moment that the gate is lifted until the stoppage and the material takes its final shape. The flow in this tool occurs on a free surface. In this work, a three-dimensional model has been developed using the computational fluid dynamics (CFD) technique for simulation. The flow behavior of fresh concrete was assumed to be non-Newtonian following the Bingham law, characterized by a non-linear shear-strain rate ratio, yield stress, and plastic viscosity. A set of numerical simulations by varying workability were conducted. Furthermore, a parametric study was conducted to examine the impact of introduced parameters in the concrete flow, including the effect of yield stress, viscosity, and density.