Experimental Investigation of Mechanical Properties of Sands Reinforced with Discrete Randomly Distributed Fiber

The addition of cementitious admixtures and/or inclusion of fibers are frequently used in practice to stabilize soils and to improve their mechanical properties. In this study, ring shear tests were conducted to investigate mechanical properties such as shear strength, angle of friction and cohesion values of randomly distributed discrete fiber-reinforced sand mixtures. The length and aspect ratio of the fibers used in the current study were 12 mm and 120, respectively. Specimens were prepared at four different fiber ratios (0.1, 0.3, 0.6, and 0.9 % by weight of sand). A series of ring shear tests were carried out on sand alone and fiber-reinforced sand mixtures at different normal stresses. The test results indicated that the addition of fiber had a significant effect on the shear strength of the sand. Shear stress of the unreinforced sand increases 1.29–2.32, 1.16–1.39, and 1.07–1.5 times at a normal stress of 50, 150, and 250 kPa, respectively with fiber inclusion. Fiber content had positive effects on improving the shear strength parameters (angle of internal friction and cohesion) of the mixtures. The cohesion and angle of internal friction of fiber-reinforced sand prepared at different ratios of fiber increased by 5.3–27.4 kPa and 2.0°–7.3° respectively. The inclusion of fibers improves the ductility of the soil by preventing the loss of post-peak strength.