Enhancing the behaviour of FRP RC Slabs using square FRP bars and Fiber Concrete

Fiber Reinforced Polymer (FRP) bars are gaining increasing acceptance in construction industry particularly in aggressive environments. Enhancing the serviceability behavior is of main points that still require further investigations. In this paper a solution for the bond and serviceability enhancement is proposed through modifying the bar shape and enhancing the concrete properties. Newly developed square glass-FRP (GFRP) bars were fabricated, tested, and the behavior was compared with circular GFRP and steel bars. The physical and mechanical properties of GFRP square and circular bars are presented. An experimental study of oneway concrete slabs reinforced with the developed square and circular GFRP and steel bars was performed. A total of 9 full-scale RC slabs were fabricated and tested up to failure to study the effect ofthe test parameters: type of reinforcement (steel versus GFRP), bar cross section shape, concrete compressive strength, reinforcement ratio of longitudinal bars, and the use of polypropylene fiber ratio. Based on the experimental test results, it was found that the bond strength of GFRP bars increased by increasing the polypropylene fiber. Also, changing the bar surface area from circular to square cross section, resulted in a slight increased in the bond strength. In addation, the behavior and ultimate flexural loads of concrete slabs reinforced with GFRP square bars were improved compared with concrete slabs reinforced with GFRP circular bars. Increasing the concrete compressive strength, resulted in improvement of the behavior of concrete slabs with GFRP square bars.