Flexural fatigue behaviour of a heated ultra-high-performance fibre-reinforced concrete

Abstract

A comprehensive experimental campaign was carried out to assess the flexural fatigue behaviour of an ultra-high-performance fibre-reinforced concrete. Several concrete mixes were submitted to room temperature, 100 °C, 200 °C, and 300 °C. Two types of reinforcement were explored: steel fibres and a combination of steel and polypropylene fibres. The influence of the addition of fibres and the temperatures in the microstructure were analysed through X-ray CT scans. In addition, the mechanical and fracture properties of the concrete were determined with monotonic tests and a connection between macroscopic and microscopic results was established to explain the fatigue behaviour. The beneficial effect of the fibres was observed essentially at a low cyclic fatigue regime. In heated concretes, the reduction of matrix porosity due to the presence of steel fibres led to significant damage after being exposed to 300 °C by spalling failure. By contrast, the concrete reinforced with polypropylene fibres maintained remarkably similar fatigue behaviour at room temperature and 300 °C.