Effects of Strength and Orientation of Steel Fiber on the Fracture Behavior of Steel Fiber Reinforced Concrete

对各种纤维增强混凝土进行了研究。它们的纤维直径通常为微米量级。钢纤维混凝土中钢纤维的直径一般为0.1~1.0 mm。研究了砂浆中钢纤维的强度和取向对钢纤维砂浆的弹性模量和抗折强度的影响。所使用的钢纤维为“新科钢纤维”，其公称尺寸为直径0.6 mm，长度30 mm，抗拉强度大于100kgf/mm^2。还使用了具有其他尺寸和强度的各种纤维。试件尺寸为40×40×160 mm^3，老化超过28天后进行试验。结果表明：(1)添加1wt%的SF都能抑制裂纹的扩展。但SF对强化的贡献超过5wt%。(2)随着SF掺量的增加，弹性模量值下降，但通过掺入最佳掺量的膨胀水泥，其下降幅度是可以控制的。(3)脂化的SF无助于强化。(4)直径10微米或长度10 mm的SFS的作用较小。(5)纵向一体化可以有效地促进经济增长。(6)在180ﾟC高压灭菌处理后，材料的弹性模量下降。

Various fiber reinforced concretes have been investigated. Their fibers have usually micro-meter order in diameter. Exceptionally, the diameter of steel fiber in SFRC is 0.1-1.0 mm. Therefore, the mechanical behaviors seems to be similar to those of RC.In this investigation, the effects of strength and orientation of steel fiber in mortar on the modulus of elasticity and facture strength of steel fiber reinforced mortar (SFRM) have been studied. The steel fiber used is "SHINKO-steel fiber", whose nominal dimensions are 0.6 mm in dia, 30 mm in length and more than 100 kgf/mm^2 in tensile strength. Various kinds of fibers having other sizes and strengths were also used. The size of specimen was 40X40X160 mm^3, and after aging for more than 28 days, tests were carried out. Results obtained are as follows : (1)Even 1 wt% addition, SF suppress the propergation of cracks. But the amount of SF contributing to strengthening is more than 5wt%. (2)The modulus of elasticity decreases by addition of SF, but by the mixing of optimum amount of expand cement, the decreasing can be controlled. (3)Greased SF dose not contribute to strengthening. (4)The role of SFs having 10 micr-meter in diameter or having 10mm in lengthare small. (5)The longitudinally oliented SF can contribute to strengthening effectively. (6)The modulus of elasticity decreased after autoclave-treatment at 180 ﾟC.