CFD simulation of movement of fresh concrete in the chute during transporting

The movement behavior of fresh concrete greatly affects the change of concrete properties and the wear of pipelines during transportation. This paper aims to predict the movement of aggregates in fresh concrete during transporting on a mesoscopic scale. A dense discrete phase model (DDPM) was utilized to describe fresh concrete, which treats fresh concrete as a double-phase fluid composed of matrix mortar and dense spherical aggregate particles that had grading particle size, random distribution, and different densities from matrix mortar. The correctness of this method was verified by comparing it with the experimental results. Then, based on the Computational Fluid Dynamics (CFD) and the DDPM, the free flow of fresh concrete in the long-distance chute was simulated. Flow behavior of fresh concrete in the chute with different inclination angles and movement characteristics of fresh concrete with different viscosities at an optimal angle were investigated, respectively. Moreover, recommended parameters for the maintenance of concrete workability in the project were provided, and it is believed that a mortar viscosity of around 50 Pa·s can effectively suppress aggregate segregation, ensuring the consistency of concrete properties during transportation.