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 (H_r) of fresh concrete after slumping was examined using a slump test. The significance degree of mortar–mortar contact parameters on the H_r was studied using an orthogonal test. The effect of the surface energy ($\gamma$) on the flow index (B_m) and flow time (T_v) of fresh concrete was studied intensively based on the L-box flow and V-funnel tests. The mortar–mortar contact parameters, $\gamma$ and rolling friction coefficient (μ_r), most significantly impacted the H_r. The mortar–mortar surface energy ($\gamma$_m-m) significantly impacted B_m and T_v compared to the aggregate–mortar and aggregate–aggregate surface energies (($\gamma$_a-m) and ($\gamma$_a-a), respectively). The effect of $\mathrm{ }\gamma$_a-a,$\mathrm{ }\gamma$_a-m, and $\gamma$_m-m on B_m was interconnected. Under appropriate parametric values, the B_m was the most stable, and the workability of fresh concrete was the best. In addition, as $\gamma$ increased, H_r and B_m decreased and T_v increased. The flowability of the fresh concrete worsened.

Keywords:

• Fresh concrete
• dEM
• flowing property
• JKR surface energy
• rheological test

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported financially by the NSFC Project [No. 51802148], Natural Science Foundation Project of Hunan Province [No. 2018JJ3435] and Doctoral Research Start-up Fund of University of South China [No. 2017XQD14].