Effect of macro polypropylene fiber and basalt fiber on impact resistance of basalt fiber-reinforced polymer-reinforced concrete

In this paper, the effect of macro nonmetallic fibers (i.e., polypropylene fibers and basalt fibers) on the impact response of basalt fiber-reinforced polymer-reinforced concrete (FRP-RC) discs is experimentally investigated using a self-developed drop-weight impact test device. The plain concrete and conventional steel-reinforced concrete samples are explored as references. The impact resistance and failure behaviors are analyzed. Statistical analyses for first-crack strength and failure strength are performed. The composite effect of basalt FRP bars and macro nonmetallic fibers on the impact energy at failure is also compared. The results indicate that the behaviors under impact load, that is, failure strength, crack number, the indent diameter, and penetration depth of the shriveled area, are greatly improved by adding of macro nonmetallic fibers, in particular macro polypropylene fibers. Additionally, the incorporation of these fibers into the basalt FRP-RC transforms the brittle failure mode into a well ductile failure mode. Two-parameter Weibull models are fitted by graphical methods and used to characterize the first crack strength and failure strength distributions. Reliability functions for first crack strength and for failure strength are estimated and failure strength can be predicted from first-crack strength by using a linear regress model. The hybrid use of basalt FRP bars and macro nonmetallic fibers demonstrates a positive synergetic effect on the impact energy at failure.