Fiber-reinforced concrete

Plain concrete is a brittle material with low tensile strain and strength capacities; the use of short, discontinuous fibers allows us to strengthen and toughen such material. Fibers are not generally added to concrete to increase its strength; the main role of the fibers is to bridge across the matrix cracks that develop as concrete is loaded, and thus to provide some postcracking ductility (or toughness). The latter may allow for a reduction of conventional reinforcement and, in structures with a high degree of redundancy, a complete replacement of rebars. The enhanced crack control makes fiber-reinforced concrete (FRC) particularly suitable for a longer durability of the structure; here, the additional cost of fiber reinforcement may be justified by savings in the maintenance costs. The consequent reduction in labor time has become a key issue for the industrialization process in the precast industry, where the rebar substitution becomes particularly convenient in thin or irregularly shaped sections. FRC is now treated as a performance-based material in several recent building codes.