Experimental study on mechanical properties of basalt fiber-reinforced silty clay

Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering. Basalt fiber is a new kind of environment-friendly and high-performance soil reinforcement material, and the mechanical properties of basalt fiber-reinforced soil have become a hot research topic. In this paper, we conducted monotonic triaxial and cyclic triaxial tests, and analyzed the influence of the fiber content, moisture content, and confining pressure on the shear characteristics, dynamic modulus, and damping ratio of basalt fiber-reinforced silty clay. The results illustrate that basalt fiber can enhance the shear strength of silty clay by increasing its cohesion. We find that the shear strength of reinforced silty clay reaches its maximum when the fiber content is approximately 0.2% and the moisture content is 18.5% (optimum moisture content). Similarly, we also find that the dynamic modulus that corresponds to the same strain first increases then decreases with increasing fiber content and moisture content and reaches its maximum when the fiber content is approximately 0.2% and the moisture content is 18.5%. The dynamic modulus is positively correlated with the confining pressure. However, the change in the damping ratio with fiber content, moisture content, and confining pressure is opposite to that of the dynamic modulus. It can be concluded that the optimum content of basalt fiber for use in silty clay is 0.2%. After our experiments, we used scanning electron microscope (SEM) to observe the microstructure of specimens with different fiber contents, and our results show that the gripping effect and binding effect are the main mechanisms of fiber reinforcement.