Influence of tire fiber inclusions on shear strength of sand

Reinforcement of soils with natural and synthetic fibers is a viable technique for increasing the soil strength. The objective of this study is to reinforce sand with tire waste inclusions. In this study, two different experimental programs were performed. In the first program, sand, tire crumb and tire crumb-sand mixtures were tested in the standard direct shear test equipment to observe the optimum content for modifying the shear strength properties of the sand. In the second program, large-scale direct shear tests were performed to observe the shear strength improvement imparted by tire waste inclusions. Two different processed tire wastes were used: tire crumb (TC) and fiber-shaped tire buffings (TB). The tire buffings were divided into two parts for representing different aspect ratios (TB1 and TB2). The following factors were studied to evaluate the influence of TC, TB1 and TB2 inclusions on the shear strength: normal stress, tire waste type, aspect ratio, and tire waste content. Three factors were found to significantly affect the shear strength values: normal stress, aspect ratio, and tire waste content. Also, it is seen that increasing the aspect ratio of the fibers increases the shear strength of the mixture.