Effect of Fibre Length on the Fracture Energy of UHPFRC

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is an advanced cementitious composite with enhanced mechanical and durability properties that outperforms conventionally used concretes in many ways. Such a material with certain properties and specifications is well suited for energy absorption facade panels and key elements of building structures that may be exposed to impacts or blast loads. It can be stated that the resistance of civil infrastructure is strongly related to the energy absorption capacity of concrete, which is the main material property that benefits from fibre reinforcement.The aim of this study is to investigate the fracture energy of the UHPFRC with various fibre aspect ratios. Different behaviour of UHPFRC in terms of fracture energy can be expected for various aspect ratios of fibres, as the fibres are the key component of the UHPFRC that result in enhanced energy absorption and dissipation capacity. The aspect ratios (length-to-diameter) of fibres used in this study ranged from 50:1 to 108:1. It was verified experimentally that the fracture energy increases as the aspect ratio increases. In addition, it was found that the dependence of the fracture energy on the aspect ratio of the fibres tends to follow a linear trend. The results provided in the present study can serve as valuable information for verifying material models, and also for design purposes.