A CFD-based numerical model for predicting the slump and slump flow of fresh concrete from a rheological perspective

Herein, a three-dimensional numerical model based on computational fluid dynamics (CFD) for fresh concrete is developed to predict the slump and slump flow. Fresh concrete is considered as a non-Newtonian fluid, and its rheological behaviour is characterised by the Bingham and Herschel-Bulkley (H-B) models, respectively. Experiments are also conducted to validate the reliability and accuracy of this model. Through parametric investigations, the influence mechanisms of relevant factors on the flow characteristics of fresh concrete are analysed and discussed. The results show that the model predictions agree well with the experimental results. The predicted results obtained using the H-B rheological model are more accurate compared to the Bingham model, with average relative errors of 1.73 %, 2.03 % and 3.95 % for slump, slump flow and T₅₀₀, respectively. The flowability of fresh concrete is negatively correlated with power index, yield stress and consistency, while it is positively correlated with density. Grey relational analysis indicates that density has the greatest effect on the results of slump and slump flow, followed by yield stress and consistency, and finally the power index. The CFD-based numerical model presented in this study provides an important approach for better understanding the flow behaviour of fresh concrete from a rheological perspective.