Spall strength of steel-fiber-reinforced concrete under one-dimensional stress state

A specially designed large-scale Hopkinson bar (φ100 mm) with hollow aluminum alloy bar as transmitted bar was used to measure the dynamic spall strength of steel-fiber-reinforced concrete (SFRC). The experimental results indicate that the steel fibers significantly enhance the spall strength of the SFRC. The enhancement of the spall strength from the steel fibers is linear with the product of the fiber influencing coefficient (α), the slenderness ratio (l/d), and the fiber volume fraction (V_f). Under dynamic loading, the value of α is higher than that observed under quasi-static loading, which is due to the enhancement of the dynamic bond strength between the fiber and the cement matrix. Furthermore, undulated fibers bring about a higher α than hooked fibers. Finally, an empirical formula is built to estimate the dynamic spall strength of SFRC under one-dimensional stress. The prediction was shown to be consistent with the experimental results. The steel fiber enhanced spall strength can be regarded as an important guideline in the design of high-performance concrete for improving the penetration resistance of protective structures.