Experimental investigation of responses of double-helix macro BFRP fiber reinforced RC beams subjected to static and impact loads

Basalt Fiber Reinforced Polymer (BFRP) fibers with double-helix geometry were proposed to reinforce concrete material in a previous study. It was observed that the double-helix geometry improved the bonding strength of fiber with concrete matrix, and adding such type of fibers could enhance the strength, energy absorption capacity and ductility of concrete material in static and dynamic loading conditions. As a continuation of the previous study, this paper repoprts experimental investigations of the responses of double-helix macro BFRP fiber reinforced concrete beams subjected to static and impact loads. To investigate the effects of fiber orientation and distribution, normal concrete and self-compacting concrete were used as matrix material based on their different flowability, to make Fiber Reinforced Concrete (FRC) and Fiber Reinforced Self Compacting Concrete (FRSCC). It was observed that the fibers tended to align in self-compacting concrete due to its high flowability, therefore the flexural performance of FRSCC was higher than FRC. In drop-weight impact tests, it was demonstrated that the incorporation of fibers into RC beam could effectively improve its energy absorption capacity, residual strength and ductility. Finally, the post-impact performances of the impacted beams were evaluated by subsequent static bending tests. It was found that with 1% volume fraction of fiber reinforcements the residual strength of RC beams was improved by over 20%.