Numerical approach to pipe flow of fresh concrete based on MPS method

Abstract

As a fundamental study of concrete pumping, this study developed a numerical method to simulate the flow and segregation of fresh concrete in pipes, based on the improved MPS (Moving Particle Semi-implicit) that has complete implicit algorithm, hereafter called I-MPS. The slip layer (LL) near the pipe inner wall was treated by the macroscopic approach, which estimates the slip resistance and the volumetric flow rate of LL from the apparent slip velocity of LL. Two constituent models were used to describe fresh concrete, called single-phase & mono-particle (SPMP) model and double-phase & multi-particle (DPMP) model, respectively. In the former, fresh concrete is considered as a single-phase granular fluid, but in the latter, fresh concrete is regarded as two-phase granular fluid with different particle shapes and sizes of coarse aggregate and matrix mortar. By comparing the numerical and theoretical pumping pressures of three concretes having slump from 13 cm to 21 cm, it was found that by using the macroscopic approach of LL and either of the constituent models, the numerical approach can predict properly the pumping pressure and velocity profile of fresh concrete in pipes. Moreover, if using the DPMP model, the segregation behavior of coarse aggregate particles during the pipe flow can also be simulated.