Performance of hybrid fiber-reinforced concrete for low-rise housing with thin walls

Aimed at improving concrete behavior of thin walls used in low-cost and low-rise housing, an experimental program was carried out to investigate the mechanical properties of Fiber-Reinforced Concrete (FRC) and Hybrid Fiber-Reinforced Concrete (HyFRC). The combination of two types of fibers is experimentally investigated in this paper based on results of flexure tests and a cost-performance analysis. The experimental program included tests of 130 standard specimens; 67 small beams and 63 cylindrical specimens. Variables of the experimental program were the type of fibers and the fiber volume content. Two types of hooked-end steel fibers with aspect ratio of 80 and 65 and one type of macro-synthetic (polyethylene) fiber with aspect ratio of 84.5 were used for the mixtures. Volume content of fibers varied between 0.15% and 0.98% for steel fibers, and between 0.16% and 0.94% for polyethylene fibers. Test results of 14 mixtures showed that only mixtures with a fiber volume content of 0.83% and 0.98% for single-type of long steel fibers and 0.94% for hybrid fibers were compliant with the residual strengths prescribed by ACI-318-14. In addition, the ratio between fiber volume contents of polyethylene and steel fibers (PF/SF ratio) should roughly between 1.0 and 1.5, but the volume content of polyethylene fiber for hybrid mixtures should be limited to 0.60%. Finally, cost-performance analysis showed that the cost of hybrid fibers mixture is about half of the steel fiber mixtures at the same performance level.