Mechanical Properties of Steel Fiber Reinforced Shotcrete in Uniaxial Tension

Katsunori FUKUI, Seisuke OKUBO, Qin YANG and Tsuneo OCHI

J. of MMIJ, Vol.112, No.2, pp.69-74 (1996)

Steel fiber reinforced shotcrete or concrete (SFRC) is used for supportingof slope and tunnel when condition is severe. Steel fibers in shotcrete isconsidered to improve crack resistance and toughness. But only few studies havebeen published on the mechanical property of SFRC.

In this study, uniaxial tensile tests of SFRC was conducted by servo-controlled testing machine to obtain complete stress-strain curves. In theexperiment, volume fraction of steel fiber in shotcrete was chosen to be0, 0.5, 1.0, 1.5%. Considering anisotropy of SFRC, two kinds of cylindricalspecimens were made boring parallel and normal to bedding plane. The experimental results in uniaxial tension can be summarized;

1) The strength and residual strength indicate anisotropy of SFRC. Both are larger when stress is applied parallel to bedding plane.

2) The strength and Young's modulus were not affected with volume fraction of steel fiber(Ｖｆ[%]), however the residual strength(σＲＥ[MPa]) increases following the equation,
σＲＥ=5×10−６×(12.5-Ｙ)５×Ｖｆ
where Ｙ[mm] is displacement.

3) In residual strength region beyond peak strength, steel fibers are gradually pulled out from shotcrete. The residual strength is caused by pulled out resistance of steel fibers.

4) The number of steel fiber appeared on the fractured surface is smaller than that on cutting surface. Fractured surface tends to develop on the weakest plane where relatively a small number of fibers cross the plane.

---