Low-velocity impact resistance of epoxy polymer concrete beams reinforced with hybrid Barchip/Forta fibers

Abstract

This study experimentally evaluates the impact resistance of epoxy-based polymer concrete beams reinforced with synthetic macrofibers—Barchip and Forta—under drop hammer loading. Fifteen beam specimens were cast using various combinations of fiber content and fly ash substitution and tested under a 2 kg mass dropped from approximately 1 m. From the resulting force-displacement data, ultimate strength, displacement, and absorbed energy were calculated. The best performance was observed in the Barchip–Forta dual-fiber specimen ABF-0-7-7, which achieved an ultimate strength of 2290.48 N, a displacement of 1.76 mm, and an energy absorption of 4.03 J, corresponding to increases of 3.2%, 42.9%, and 47.6%, respectively, over the unreinforced control. In contrast, the weakest specimen, ABF-5-3.5-0, showed reductions of 32.6% in stress and 42.3% in energy absorption. These results confirm that combining Barchip and Forta macrofibers significantly enhances both strength and toughness, transforming the failure mode from brittle fragmentation in the control to a ductile, cohesive failure in the hybrid specimens.