Method for manufacturing fiber composite for reinforcing concrete, and concrete comprising fiber composite manufactured thereby

A method of manufacturing a fiber-reinforced concrete, the method comprising:

• twisting two strands of polyethylene terephthalate filament yarns for a fiber composite to have turns per meter (TPM) of 200 to 500 to form a helix structure in which 2 strands of yarns form an angle 50 to 100° in an axial direction of the fiber composite from a surface of the fiber composite to prevent reduction in spinning resistance performance;
• and
• forming a compound bond between the fiber composite and an epoxy compound coating solution by drying and heat-treating the fiber composite after immersing the fiber composite in the epoxy compound coating solution, wherein:
• the immersing is performed with 0.3 to 4% of solid content in the epoxy compound coating solution based on a weight of the twisted fiber composite,
• the drying is performed at 100 to 150° C., and the heat-treating is performed at 220 to 250° C. for 50 to 90 seconds such that the epoxy compound coating solution penetrates a microstructure in the fiber composite to function as chemical bond with the fiber composite and an anchor to ensure cohesion with the fiber composite and to achieve hydrogen bond between a hydrophilic group of the epoxy compound coating solution and concrete by mixing the fiber composite with the concrete, thereby increasing cohesion with the concrete and improving reinforcement performance,
• and wherein the fiber composite has an initial modulus of 80 g/d to 110 g/d, wherein the initial modulus is selected such that the fiber composite exhibits non-linear threshold rebound behavior during shotcrete application, with increased rebound rate occurring above 110 g/d, such that the fiber composite maintains linearity during concrete mixing and shotcrete injection and exhibits a reduced rebound rate compared with fibers having modulus greater than 110 g/d.