Mechanical properties of steel fibre–UHPC interface: Experimental study and numerical simulation

The aim of this study was to investigate the interfacial mechanical attributes between steel fibre (SF) and an ultra-high-performance concrete (UHPC) matrix. Using both experimental testing and numerical simulation, a comprehensive analysis on the pull-out process of SF from the UHPC matrix was conducted. The effects of fibre embedment depth, fibre diameter and fibre embedment angle on the mechanical properties of the SF–UHPC interface were examined. In the fibre pull-out tests, the maximum pull-out force of the group of specimens with different embedment depths showed a trend of rapid rise and then slow development, and the pull-out work increased with an increase in embedment depth. The maximum pull-out force and pull-out work of the group with variable fibre diameters increased with an increase in fibre diameter. The maximum pull-out force and pull-out work of the group with different embedment angles increased first and then decreased with an increase in embedment angle. The maximum pull-out force was 72.5 N when the embedment angle was 45° and the maximum pull-out work was 214.4 N.mm when the embedment angle was 30°. The results of finite-element simulations were found to be in good agreement with the experimental results.