Investigations on Ni-Ti Shape-Memory Alloy Fiber-Reinforced GGBS Mortar in Aggressive Environment

Abstract

The durability of fiber-reinforced concrete (FRC) is a critical area of concern when considering the lifespan of a structure. Current advancements have a few constraints connected with aging, durability, and corrosion. An alternative reinforcement material like the superelastic shape-memory alloy, with high energy dissipation capabilities and better corrosion resistance, can improve the life expectancy of structures. This study evaluates the corrosion resistance of nickel-titanium shape-memory alloy (Ni-Ti SMA) fibers in the mortar and compares it with steel fibers. Ground granulated blast furnace slag (GGBS) is utilized as a partial replacement for cement since GGBS is an industrial waste that helps enhance concrete’s durability properties and promotes a sustainable construction practice. Tests were conducted to estimate the engineering properties like compressive strength, flexural strength, and split tensile strength of Ni-Ti SMA fiber-reinforced GGBS mortar. Mortar with Ni-Ti SMA fibers showed greater split tensile strength, whereas the compressive strength and flexure strength were more for mortar mixes with steel fibers. This was due to the greater modulus of elasticity value of steel fiber when compared with the Ni-Ti SMA fiber. Durability features were accessed in terms of resistance toward acid, sulfate, chloride, and seawater. The results confirmed that Ni-Ti SMA fiber-reinforced GGBS mortar was highly durable, while the steel fibers in the steel fiber-reinforced GGBS mortar got corroded, resulting in a less durable FRC. This was further studied by investigating the morphology of specimens subjected to durability tests in terms of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) analysis. The outcomes revealed that Ni-Ti SMA fibers were free from corrosion and exhibited superior durability when used in FRC. Many researchers have investigated the efficiency of Ni-Ti SMA fiber as an FRC material, and it is well-proven that these fibers improve ductility and can take recoverable strains up to 8% or even more. This property of superelasticity can be effectively used in seismic-resistant structural elements. This study explores the corrosion resistance of Ni-Ti SMA fibers when subjected to extreme environmental conditions. The research identifies the potential of Ni-Ti SMA fibers to be used as a corrosion-resistant FRC material. Ni-Ti SMA fibers have better impact resistance, offering new options for constructing ductile structural elements that can lessen the damage caused by impact, blast, and dynamic loading. The high corrosion resistance, better durability, and long fatigue life of these fibers make them applicable for industrial buildings, offshore structures, or any system subjected to an aggressive environment.