Microstructure and bonding behavior of fiber-mortar interface in fiber-reinforced concrete

Abstract

The interfacial properties between fiber and matrix play a critical role in the overall mechanical responses of composite materials. In this paper, the glass fiber-mortar interfacial microstructure in fiber reinforced concrete (FRC) is visualized and characterized using X-ray microscopy. Additionally, three types of fiber-mortar interface (glass fiber, high modulus polyvinyl alcohol (PVA) fiber, and basalt fiber) are analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The results revealed a lot of microcracks along with the glass fiber-mortar interface; moreover, the hydration product of the glass/PVA/basalt fiber-mortar interface was much lower than that of the mortar matrix. Because microcracks or lower hydration product have such a negative effect on the interfacial bonding between fiber and mortar, the objective of this paper was to provide an analysis of this problem through extensive testing of their bonding properties. Specimens made of three types of fiber were tested along with three different mortar types were tested under tensile stress and a combined stress state to investigate the interfacial bond properties between fiber and mortar. Results show that both of the tensile and shear bond strength of the interface were not only improved by stronger mortar matrix, but also significantly affected by fiber type. Furthermore, when the 2 interface failed by slipping along the interfacial area, the interface showed an increasing shear bond strength with the increase of compressive stress. This was not the case when failure was due to the crushing of mortar. Finally, the FRC splitting tensile strength was tested to demonstrate the bonding mechanism effects on the FRC mechanical properties.

Enhancement of Concrete Pipes Through Reinforcement With Discrete Fibers

“…In the case of Pipe #8, with fibers of medium aspect ratio, some fiber pull-out was observed but fiber rupture was still prevalent. For Pipe #15, which incorporated coarse fibers, fiber pull-out with a bond strength, τ, of 10 MPa (1450 psi) [8] yielded a satisfactory analytical prediction of experimental results. Fiber rupture was assumed to be prevalent in Pipe #7 with the smallest fiber diameter and highest fiber aspect ratio.…”

Effect of Temperatures and Moisture Content on the Fracture Properties of Engineered Cementitious Composites (ECC)

“… is SW > SSW > D, while is SW > SSW > D. The fiber-matrix interface characteristic plays a major role in the overall performance of fiber-reinforced cement composites [ 44 ]. PVA fiber is a hydrophilic material [ 45 ], which allows the hydrophilic fiber to fully exert the bonding performance between the matrix and fiber under the lubrication effect of moisture, and the improvement of fiber bonding performance is to promote slippage between the cement base and the fiber substrate.…”

The effect of basalt fiber addition on cement concrete: A review focused on basalt fiber shotcrete

“…A series of relevant standards for basalt fiber and basalt fiber reinforced concrete were formulated in China, such as Shortcut basalt fiber for cement concrete and mortar, Basalt fiber classification and code, Highway engineering basalt fiber and its products (GB/T 23265-2009(GB/T 23265- , 2009Institute of Highway Science, 2010;GB/T 38111-2019GB/T 38111- , 2019. In addition, scholars conducted a lot of research on basalt fiber reinforced concrete, and studied the influence of adding fiber on the early shrinkage, early cracking, impact toughness, compressive strength, flexural and tensile strength, flexural strength and impermeability of concrete (Dong, 2011;He et al, 2012;Sun et al, 2022;Su, 2012;Hemalatha and Ramesh, 2019;Ralph et al, 2019;Alekseev and Kurilko, 2020;Hong et al, 2020;Khan et al, 2021;Li et al, 2022a). However, most studies only focus on a certain aspect of the performance of BFRC, which was not systematic and comprehensive.…”