Numerical simulation on slump test of fresh concrete based on lattice Boltzmann method

In this paper, the rheological mechanism of fresh concrete material was investigated and the method of evaluating its rheological property was optimized by combining the slump test of five groups of fresh concrete and lattice Boltzmann method (LBM). The rheological parameters of fresh concrete samples based on Herschel-Bulkley (H–B) model and Bingham model were obtained by rheometer and equation derivation with nonlinear and linear fitting approaches. The comparison of Bingham and H–B models in the simulation results of the slump test demonstrated that the H–B model was more accurate in expressing the rheological characteristics of the fresh concrete. In the Bingham model, the errors of slump s, spread sf and the time of spread reaching 500 mm T500 ranged from 2.00% to 39.29%. The errors of s and sf in the H–B model were less than 2%, and the error of T500 was about 5%. Afterwards, the results of the slump test were predicted based on the H–B model. The effects of rheological parameters (power-law index consistency index and yield stress) on velocity, viscosity, shear strain rate, flow rate and external contour were revealed.