2 - Fiber classifications and physical and mechanical properties of different fibers used in alkali-activated composites

Abstract

Due to the poor tensile properties of alkali-activated materials, the incorporation of fibers (natural and synthetic) has received substantial attention among concrete technologists and the construction industry. Previous studies have revealed that the incorporation of natural and synthetic fibers has a positive effect on the mechanical and durability properties of alkali-activated materials. In this direction, investigating the classification of fibers and their physical and mechanical properties is of critical importance, given their effects on the final properties of fiber-reinforced alkali-activated materials. To this end, this chapter discusses the classification of fibers based on the primary source, materials used, and production method, including natural fibers (mineral, plant, and animal fibers) and synthetic fibers (organic, inorganic, and steel fibers). The physical (e.g., fiber length, diameter, density, and water absorption) and mechanical properties (e.g., tensile strength, elastic modulus, and failure elongation) of different fibers are also reviewed. Based on the literature, it can be concluded that both natural and synthetic fibers exhibit various advantages and disadvantages, and hence the selection of fiber should be based on the desired requirements and potential applications of fiber-reinforced alkali-activated materials.