Impact resistance of a sustainable Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) under pendulum impact loadings

• A sustainable UHPFRC is developed based on particle packing model.
• A modified pendulum impact set-up is designed and produced.
• Impact resistance of UHPFRC under pendulum impact is investigated.
• The results obtained from different impact set-up are compared.
• Mechanism of the impact process is studied and discussed.

This paper presents the impact resistance of a sustainable UHPFRC member under pendulum impact loadings. The modified Andreasen and Andersen model is employed for the concrete matrix design, and two pendulum impact set-ups are utilized in the experiments: “Charpy Impact Device” and “Modified Pendulum Impact Device”. For the Charpy impact test, the obtained results show that the fibre length plays a dominating role in improving the energy dissipation capacity of the sustainable UHPFRC. With a constant total steel fibre amount, a higher proportion of short straight fibres decrease the energy absorption capacity of the concrete sample. However, the results obtained from the “Modified Pendulum Impact Device” demonstrate that, compared to the concrete with single sized fibres, the addition of hybrid steel fibres is more beneficial for improving the energy dissipation capacity of the sustainable UHPFRC under pendulum impact. Subsequently, the inconsistent results obtained from both investigated test methods are analysed and discussed. Based on the obtained experimental results, it can be concluded that there is an urgent need for a systematic standard for evaluating the impact resistance of UHPFRC.