The effect of JKR surface energy on the flowing property of fresh concrete in DEM simulation

Abstract

The effect of Johnson–Kendall–Roberts (JKR) surface energy on the flowing property of fresh concrete was numerically studied. The fresh concrete was simplified into coarse aggregate and mortar, both described as the particles. The Hertz-Mindlin with JKR contact model was employed to describe the constitutive relationship of fresh concrete. The contact parameters were calibrated through experiment and numerical simulation of multiple flow tests. The impact of these contact parameters on the residual height (Hr) of fresh concrete after slumping was examined using a slump test. The significance degree of mortar–mortar contact parameters on the Hr was studied using an orthogonal test. The effect of the surface energy ( γ ) on the flow index (Bm) and flow time (Tv) of fresh concrete was studied intensively based on the L-box flow and V-funnel tests. The mortar–mortar contact parameters, γ and rolling friction coefficient (μ r), most significantly impacted the Hr. The mortar–mortar surface energy ( γ m-m) significantly impacted Bm and Tv compared to the aggregate–mortar and aggregate–aggregate surface energies (( γ a-m) and ( γ a-a), respectively). The effect of γ a-a, γ a-m, and γ m-m on Bm was interconnected. Under appropriate parametric values, the Bm was the most stable, and the workability of fresh concrete was the best. In addition, as γ increased, Hr and Bm decreased and Tv increased. The flowability of the fresh concrete worsened.