Analysis on the Triaxial Shear Behavior and Microstructure of Cement-Stabilized Clay Reinforced with Glass Fibers

Bo Ruan,Shilong Zheng,Jidong Teng,Chao Ma,Hui Ding,Jia-Wen Zhou

doi:10.1155/2020/8842091

Bo Ruan, Shilong Zheng + Show 4 more

Open Access

https://doi.org/10.1155/2020/8842091

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Abstract

A series of triaxial compression tests were conducted to investigate the influence of the fiber content and confining pressure on the shearing characteristics of cement-stabilized clay reinforced with glass fibers. The glass fiber contents were 0, 1‰, 2‰, 3‰, and 4‰ by weight of the dry soil. The stress strain and volume change behavior, shear strength, and energy absorption of the test specimen were obtained. The results indicate that the inclusion of glass fibers can increase the shear strength, inhibit the volumetric dilation of the test specimen, and improve its brittle behavior. The cohesion of the cement-stabilized clay reinforced with 4‰ glass fiber content is 2.8 times greater than that of the cement-stabilized clay. The effect of the fiber content on the friction angle is not obvious. It is found that the glass fiber reinforcement is more substantial under a low confining pressure. The scanning electron microscopy test results show that the surface of the glass fiber is wrapped with cement hydrate crystals, which increases the bite force and friction between the fiber and the soil particles. A single fiber is similar to an anchor in the soil, which enhances the mechanical properties of the cement-stabilized clay reinforced with fibers.

Highlights

Clay is widely distributed in southern China and has poor mechanical properties and poor water stability
According to the national criterion for high-speed railway design in China [1], clay belongs to group C or group D, which cannot be directly used as the subgrade filling material of high-speed railways. e physical or chemical properties of clay should be improved before it is selected as a filling material in highspeed railway subgrades
E increase in the strength with increasing fiber content is attributed to the fiber tensile strength within the specimen and the friction force between the fibers and cement hydrates

Summary

Introduction

Clay is widely distributed in southern China and has poor mechanical properties and poor water stability. Hamidi and Hooresfand [29] found that the incorporation of polypropylene fibers and glass fibers can reduce the initial stiffness of cement-stabilized soil and increase the cohesion and internal friction angle of cement-stabilized soil [30,31,32]. Consoli et al [33,34,35] found that the initial stiffness of cement-stabilized soil was not affected by fibers, and both glass fibers and polyester fibers could reduce the cohesion of cement-stabilized soil and increase the friction angle. It was evident from past studies that different scholars still had different views on the effects of fibers on the cohesion, internal friction angle, initial stiffness, and volumetric strain of cement-stabilized soil, and a consistent conclusion has not been reached. Specific gravity Liquid limit (%) Plastic limit (%) Plasticity index Optimum moisture content (%) Maximum dry density (g/cm3) Cohesive strength (kPa) Internal friction angle (°)

Materials and Methods

Test Program

Stress-Strain Relationships and Volume Change Behavior