Experimental and numerical study for the bending behaviour of UHPC beams with waste foundry sand

Abstract

Waste foundry sand (WFS) is a waste material inevitably generated during the casting process, the resourceful recycling of which has received much attention in recent years. WFS has been tried for various concrete preparations without involving ultra-high performance concrete. In this study, the bending behaviour of ultra-high performance concrete beams with WFS as an aggregate replacement (i.e., FUHPC) was investigated. Firstly, the bending tests for 6 FUHPC beams with the variable of WFS substitution rate (0%, 10%, 20% and 30%) and water-binder ratio (0.16, 0.18 and 0.20) were carried out, and the effects of the two were discussed based on the failure mode, load–deflection response and load–strain response of the beams. Then, finite element simulation was used to further explore the bending behaviour of FUHPC beams. Finally, the applicability of the equation in the code for calculating the bending capacity of FUHPC beams was evaluated. The results showed that the bending performance of FUHPC beams first improved and then decreased as the WFS substitution rate and water-binder ratio increased. The best bending performance of FUHPC beams was achieved when the two were 20% and 0.18, respectively. In this case, the cracking load, yield load and ultimate load of FUHPC beam were 1.26, 1.23 and 1.12 times higher than those of the beam without WFS, respectively, and the ultimate strain was also elevated. When the WFS substitution rate was too large (30%), the damage of FUHPC beams showed certain brittle characteristic. The plastic damage of FUHPC beams was mainly concentrated in the pure bending section. Tensile reinforcement strength, reinforcement rate and especially the beam height have obvious positive effects on the bending performance of FUHPC beams. The theoretical equation of bending capacity suggested by the code CECS 38:2004 is applicable for FUHPC beams.