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

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 degrees C, 200 degrees C, and 300 degrees 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 degrees C by spalling failure. By contrast, the concrete reinforced with polypropylene fibres maintained remarkably similar fatigue behaviour at room temperature and 300 degrees C. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study found that the addition of fibers in ultra-high-performance fiber-reinforced concrete can have a beneficial effect in the low cyclic fatigue regime. When heated, concrete with steel fibers led to a reduction in matrix porosity and significant damage at 300 degrees C due to spalling failure, while concrete reinforced with polypropylene fibers maintained remarkably similar fatigue behavior at room temperature and 300 degrees C.