37 / 2022-03-21 12:24:58

Numerical modelling of fresh concrete for slump tests on the basis of lattice Boltzmann method

fresh concrete;,slump test,lattice Boltzmann method,numerical simulation

The rheological mechanisms within fresh concrete materials were investigated and the method of evaluating the rheological properties of concrete by slump test was optimized by combining five sets of fresh concrete and the Lattice Boltzmann Method (LBM). By comparing the slump test simulation results of Bingham and Herschel-Bulkley (H-B) models, it was found that the H-B model expresses the rheological characteristics of fresh concrete with higher accuracy. The errors of slump s, spread s_f and the time of spread achieving 500 mm T₅₀₀ for the Bingham model fluctuated between 2.00% and 39.29%.  In contrast, the errors of s and s_f of the H-B model did not exceed 2%, and the error of T₅₀₀ was about 5%. The prediction of the slump test was carried out based on the H-B model. The prediction results demonstrated that the rheological parameters in the H-B model have a significant effect on the flowability of the fresh concrete at the beginning of the slump test.  The velocity distribution of shear-thinning concrete produced severe polarization with a maximum velocity of 1.4 m/s; while the velocity distribution of shear-thickening paste was relatively uniform with a magnitude around 0.5 m/s.