Reinforcement bar and method for manufacturing same

1 . Reinforcement bar for concrete structures, comprising a plurality of parallel fibers, tensioned, comprising at least one of basalt, carbon, or glass fiber, embedded in a cured matrix, the bar having an average length in a range of 20 mm to 200 mm, and an average diameter in a range of 0.3 mm to 3 mm, the bar being made of at least one fiber bundle comprising the plurality of parallel fibers, characterized in that at least a part of a surface of the bar is deformed to provide a deformation of at least a part of the surface of the bar prior to or during a curing stage of the matrix such that the deformation is secured in the cured matrix, by means of:

a) one or more strings of an elastic or inelastic, tensioned material being helically wound around said at least one fiber bundle comprising the plurality of parallel fibers prior to curing of the matrix in which the fibers are embedded, maintaining the fibers in a parallel state during curing and providing an uneven external surface with longitudinally arranged helical indents in a longitudinal direction on the surface of said at least one fiber bundle in the matrix of the reinforcement bar, and

b) said bar being provided with a surface shape and/or texture which contributes to bonding with the concrete thereby providing a roughened surface,

wherein a higher tension is applied to the one or more strings than the at least one fiber bundle, thereby providing a twist in the at least one fiber bundle.

2 . Reinforcement bar according to claim 1 , wherein an additional one or more strings are helically wound in an opposite direction of the one or more strings around the said at least one embedded fiber bundle in the matrix.

3 . Reinforcement bar according to claim 1 , wherein a pitch length of a helix is in the range of 10 mm to 22 mm.

4 . Reinforcement bar according to claim 1 , wherein an angle α of a helix formed by the helically wound string around the at least one fiber bundle with respect to a center line of the reinforcement bar is in a range between 4 to 8 degrees.

5 . A method for manufacturing the reinforcement bar as defined by claim 1 , wherein the bar comprises the plurality of parallel fibers comprising at least one of basalt, carbon, or glass fiber embedded in the cured matrix, the bar having a length in the range 20 mm to 200 mm, and a diameter in the range of 0.3 mm to 3 mm, characterized in that the bar is made of the at least one fiber bundle, which prior to or during a curing process are provided with a surface texture that facilitates bonding with the concrete, said surface texture is obtained by helically winding one or more strings of an elastic material around the at least one fiber bundle.

6 . Method according to claim 5 , wherein the one or more strings are helically wound prior to curing of the matrix holding the fibers in the parallel state during curing and providing an uneven external surface in a longitudinal direction of the reinforcement bar.

7 . Method according to claim 6 , wherein another one or more strings are helically wound in opposite directions of the one or more strings.

8 . Method according to claim 6 , wherein the one or more strings are helically wound at an angle α which is in a range between 4 and 8 degrees with respect to a center line of the bar.

9 . A method comprising:

mixing the reinforcement bar as defined in claim 1 with green concrete, and

repairing a cracked concrete structure with the mixture, the mixture configured to provide structural integrity to the concrete structure.