7.15 : Fiber Reinforced Concrete

Fiber-reinforced concrete significantly enhances the structural and nonstructural properties of traditional concrete by incorporating fibers like steel, glass, and polymers. These fibers, varying from natural ones such as sisal and cellulose to manufactured ones like polypropylene and Kevlar, are mixed into hydraulic cement with aggregates. Steel fibers, often preferred for their robustness, contribute to improved ductility, toughness, and post-cracking performance. The concrete is classified based on the fiber volume, influencing its resistance to shrinkage cracking, modulus of rupture, and impact resistance.

Unlike plain concrete which fails upon reaching its ultimate flexural strength, fiber-reinforced concrete exhibits superior load-carrying capacity beyond this point due to its enhanced ductility. Mixing and handling techniques of fiber-reinforced concrete are adapted based on the type of fibers used. The fibers' aspect ratio, shape, texture, and structure play critical roles in defining the concrete's overall performance, making fiber-reinforced concrete a preferred choice for construction projects requiring higher durability and strength. The properties such as modulus of elasticity, Poisson's ratio, and the ability to avoid large lateral stresses are important considerations. Common uses include precast decorative panels, fire-resistant sheets, and concrete overlays, with the material's utility extending to both permanent structures and temporary formworks.