Reinforcement bar and method for manufacturing same

A set of reinforcement bars for reinforcement of concrete structures, comprising:

• a plurality of reinforcement bars that are configured to be mixed together in random orientations with green concrete, wherein the reinforcement bars each comprise
• at least one fiber bundle comprising a plurality of substantially parallel fibers, being made of basalt, carbon, or glass fiber, and being embedded in a cured matrix,
• wherein each of the fibers of each of the at least one fiber bundle has a cylindrical shape and a cross section, the cross section being circular or oval, and
• one or more strings of an elastic or inelastic, tensioned material helically wound around the at least one fiber bundle of the fibers prior to a curing stage of the matrix in which the at least one fiber bundle is embedded,
• wherein the one or more strings maintain the fibers in a substantially parallel state during the curing stage and deform at least a portion of an external surface of the at least one fiber bundle prior to or during the curing stage of the matrix to such that the one or more strings form longitudinally-arranged helical indents extending in a longitudinal direction along the length of the bar and the external surface of the at least one fiber bundle is an uneven external surface due to the helical indents formed by the one or more strings,
• wherein the reinforcement bars each have a length in the range of 20 mm to 200 mm, and a diameter in the range of 0.3 mm to 3 mm,
• wherein the reinforcement bars each have a roughened surface shape and/or texture which contributes to bonding with the concrete structures when in a hardened or cured state,
• wherein a higher tension is applied to the string than the bundle, thereby providing a twist in the bundle.