Investigation of Shear Strength of Clay Soil – Geotextile by using the BCF Waste Fibers

By placing the reinforcing elements, the shear strength of the soil improves. Several studies have been carried out on reinforcing of coarse grained soils, and less has been done on fine-grained soils. Researches show that the shear strength of fine grained soil-geosynthetics is weaker than the coarse soils and should be to improve its interaction with reinforcing elements. In this research, soils with about 80% passing the No.200 sieve and two types of non-woven geotextiles have been used. Shear strength of soil was considered by adding polypropylene waste fibers with 0.2%, 0.7% and 1.2% by weight of dry soil. Shear strength of soil – geotextile determined by large direct shear machine and some of these tests were done in vertical loading – reloading conditions. Experimental results show that vertical loading – reloading conditions increase interface shear strength. Addition of 0.7% fibers increase interface shear strength up to 15% and 9% in loading – without reloading and loading - reloading conditions, respectively. Also increasing of normal stress in loading step, geotextile with higher tension strength and reduction of moisture content are factors improving shear strength of soil-geotextile in this study.