Spall fracture properties of steel-fiber-reinforced concrete

A large-size Hopkinson pressure bar equipment was used to explore the spall fracture properties of steel-fiber-reinforced concrete (SFRC) by analyzing the strain wave profiles in the absorption bar behind the specimen. The experimental results indicate that the spall strength of the SFRC is related to the steel-fiber volume fraction, the compressive strength of concretes and the load rate. And the proposed empirical formula shows the above relationship. Compared with the plain concretes, the SFRC has higher spall strength and more ability to prevent damage evolution and crack growth. The spall fracture processes of the SFRC recorded with a high-speed camera display that the flaking-off of scabs are due to the momentum effect of stress wave trapped in scabs and there lie few multiple fractures in scabs. These fracture phenomena of the SFRC differ distinctly from those of the plain concretes under the same loading conditions. It explains that steel fibers can improve the ability of concrete to prevent spall fracture. Investigated conclusion is helpful to the corresponding numerical simulation and engineering design.