Cracking Behaviour of FRC Beams under Long-Term Loading

The extensive research activity carried out over the last decades on fibrereinforced concrete (FRC) has shown that such material has enhanced mechanical and durability properties compared to plain concretes. The presence of short fibres in the concrete mass allows to control cracking and have moderate time-dependent effects. Compared to plain concrete, FRC flexural members show a higher number of cracks with reduced mean width. The experimental study presented herein discusses the mechanical behavior of FRC flexural beams subjected to sustained service load and environmental exposure for 72 months. The effects of different short fibers (polyester and steel), sustained loading and aging were investigated. A comparison with the results of a previous research is shown, with reference to the same kind of beams exposed for 17 months under the same conditions. The results show the beneficial effects of the fibers in terms of reduced crack width and increased flexural stiffness. The mechanical tests also highlighted how the presence of short structural fibers could play an effective role in mitigating creep effects in the concrete elements.