Improving the Interfacial Bond Properties of the Carbon Fiber Coated with a Nano-SiO2 Particle in a Cement Paste Matrix

Gwang-Hee Heo,Ki-Chang Song,Jong-Gun Park,Zhongguo John Ma,Hyung-Min Jun,Jong-Ho Park

doi:10.1155/2020/8838179

Abstract

To improve the interfacial bond properties of the carbon fiber coated with a nano-SiO2 particle in a cement paste matrix, the present study proposed a method of coating nano-SiO2 particles on the surface of the carbon fiber by the chemical reaction of a silane coupling agent (glycidoxypropyltrimethoxysilane, GPTMS) and colloidal nano-SiO2 sol in an alkaline environment. To verify whether a nano-SiO2 particle was effectively modified on the surface of the carbon fiber, the surface morphology, chemical composition, and chemical structure were characterized and analyzed by several techniques such as the scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), and Fourier-transform infrared spectroscopy (FT-IR). Nano-SiO2 particles were entirely covered and uniformly distributed on the surface of the carbon fiber, resulting in the formation of a thin layer of nano-SiO2 particles. A thin layer of nano-SiO2 particles reacted with Ca(OH)2 to form a calcium-silicate-hydrate (C-S-H) gel, which is most helpful to increase the form between the fiber and the matrix. In addition, a pull-out test of the tow carbon fibers was performed to verify the effect of the new surface modification method on the interfacial bond properties of the carbon fiber embedded in the cement paste matrix. The experimental results showed that the frictional bond strength of the carbon fiber coated with a nano-SiO2 particle was significantly increased compared to the plain carbon fiber. These results were expected to improve the interfacial bonding force of hardened cement paste from the formation of the C-S-H gel produced through the chemical reaction of nano-SiO2 particles coated on the surface of the carbon fiber with Ca(OH)2. In particular, it was confirmed that the carbon fiber-reinforced cement paste (CFRCP) specimens coated with a nano-SiO2 particle and silica fume which replaced 10 wt.% of cement by mass showed the highest pull-out resistance performance at 28 days of age. The new surface modification method developed in this study can be very beneficial and helpful in improving the interfacial bond properties of CFRCP.

Highlights

Around the world, cement-based composites are indispensable to the technological development of modern civil engineering and have been widely used in architectures and infrastructure facilities [1,2,3,4]
Owing to the reaction of Ca(OH)2 like this, large contents of oxygen and silica, as well as calcium, elements were detected in a thin layer of hydration products covering the surface of the carbon fiber. is is because a thin layer of nano-SiO2 particles coated on the surface of modified carbon fibers reacted with Ca(OH)2, which induced formation of a cement hydration product through creation of C-S-H gel
A method of effectively modifying the surface of carbon fibers with nano-SiO2 particles by chemical adhesion has been proposed to improve the interfacial bonding force between the fibers and the cement matrix as cement reinforcement materials. e surface morphology, chemical composition, and chemical structure of the carbon fiber surface modified with a nano-SiO2 particle were analyzed using scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), and Fourier-transform infrared spectroscopy (FT-IR). e analysis results showed that a thin layer of nano-SiO2 particles coated was uniformly distributed on the surface of the carbon fiber

Summary

Introduction

Cement-based composites are indispensable to the technological development of modern civil engineering and have been widely used in architectures and infrastructure facilities [1,2,3,4]. The types of fibers used in FRCC are steel, carbon, glass, polyvinyl alcohol (PVA), polypropylene (PP), polyethylene (PE), asbestos, cellulose, and so on Among these fibers, steel fiber as cement reinforcing materials has been widely used for constructing infrastructures or facilities such as road pavement, tunnels, bridges, and dams and has excellent mechanical performance with high tensile strength and ductility [4, 15,16,17]. Unless the bond strength is sufficient, the advantages of high elasticity and high strength owned by the fiber cannot be sufficiently exhibited For this reason, many studies have been conducted to increase the bond strength between the fibers and the matrix in the cement paste matrix, thereby increasing the fiber enhancement effect, and to improve the mechanical properties of the cement composite material [22,23,24,25]

Methods

Results

Conclusion