Modulus of Rupture (Ultimate Bending Strength) of Sprayed Steel-Fiber Reinforced Mortar.

Sprayed steel-fiber reinforced mortar (SFRM) or concrete (SFRC), one of the future promising composite materials, is considered to suit today's rapid excavation by a tunnel boring machine, a boom header or a continuous miner. In this study, four-point bending tests were performed measuring load and deflection in the air-dried condition. The pre-failure characteristics such as Young's modulus did not change so much. However, the residual strength increased dramatically in behalf of the steel-fiber reinforcement. The peak strength at steel-fiber content of 1.5 % became twice as much as that of plain mortar. The experimental results in bending together with the results of uniaxial tension and compression tests were analytically examined and discussed. It was found that the peak strength in bending was strongly correlated with the residual strength in tension. An equation to estimate the peak strength in bending was proposed and the calculated results were compared with the experimental results.