Durability of FRC beams exposed for long-term under sustained service loading

Fiber Reinforced Concrete (FRC) is a material obtained by adding fibers to the concrete matrix. Fibers resist the crack opening and develop tensile residual strength. The extensive research activity carried out over the last decades on FRC has shown that such material has enhanced mechanical and durability properties as compared to plain concretes (PC) due to the cracking control. In fact, FRC flexural members show a higher number of cracks with reduced width; this occurrence involves an improved mechanical behaviour mostly under service conditions and a higher durability due to the reduced attacks of aggressive agents and to the more controlled effect of long terms phenomena. The experimental study presented herein discusses the long-term behaviour of FRC flexural beams subjected to sustained service load and environmental exposure up to 72 months. The effects of different short fibers (polyester and steel), sustained loading and aging were investigated. The results show the beneficial effects of fibers in terms of reduced crack width and increased flexural stiffness. The experimental data on cracking behaviour are finally compared with the analytical predictions obtained according to the formulation provided by fib Model Code 2010.