DEM study on the effect of the coarse aggregate shape and content on the flow performance of fresh concrete

Le résumé fourni par la source

In this paper, the effect of the coarse aggregate (CA) shape and content on the flow performance index of fresh concrete in the L-box test (Bm) was investigated based on Discrete Element Method (DEM). The Hertz-Mindlin-JKR (Johnson-Kendall-Roberts) contact model was used to characterize the constitutive relationships of fresh concrete. The parameters of contact model were calibrated by the experiment and simulation of the slump test, L-box flow test and V-funnel test. The shape of CA was quantitatively characterized, and a functional relationship between the specific surface area of concrete (SC) and surface energy was established. The effect of CA shape and content on Bm was studied numerically. The simulated results of single-shape CA concrete in L-box test show that the shape of CA affects the resultant force and flow velocity of the tracked concrete in the x direction, thus affecting the Bm. The smaller the sphericity index of CA, the larger the specific surface area and the smaller the Bm. The results of orthogonal tests show that the CA content of different shape in concrete affects Bm with different degree. The larger the specific surface area of coarse aggregate (SCA), the greater the negative effect on Bm. A linear relationship between SC and Bm was established. An equation for predicting Bm based on shapes and contents of CA was presented. It shows that the more complex the shape of CA and the higher its content, the smaller the Bm.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.