Reinforcing bar and method for manufacturing the same

Abstract

Disclosed are an improved reinforcing bar and methods for manufacturing the same. The improved reinforcing bar is made from a high strength material, and has a circular or oval or elliptical cross section and deformation of the axis in a single plane or in multiple planes. The methods for manufacturing the improved reinforcing bar include a hot working process and a cold working process. The undulating/wavy bar with axis deformation can improve the anchorage of the bar in concrete and the bond strength without comprising any surface modifications. The amplitude and pattern of axis deformation of the bar can avoid stress concentration and its ill effects.

1 - 8 . (canceled) 
     
     
         9 : A method for manufacturing of an improved reinforcing bar (REBAR) for reinforced concrete constructions and reinforced concrete structures by hot working comprising steps of:
 making of billet for high strength bar of steel; reheating the said billet;   rolling the said billet in a rolling mill and making bars of the desired size and shape;   deforming the said bars using gear rollers or by any other device or means;   optionally providing any heating/cooling treatment;   cutting bars into desired lengths using shears   cooling of said bars in a cooling bed.   
     
     
         10 : A method for manufacturing of an improved reinforcing bar (REBAR) for reinforced concrete constructions and reinforced concrete structures by cold working comprising steps of:
 making of billet for high strength bar of steel;   reheating the billet;   rolling the said billet in a rolling mill to make bars of the desired size and shape;   cutting bars into desired lengths using shears;   cooling of said bars in a cooling bed;   deforming the said bars using gear rollers or by any other device or means;   optional annealing to relieve residual stresses.   
     
     
         11 : The method for manufacturing of an improved bar of  claim 9  wherein said rolling mill process is followed by quenching of said bar in case of thermo mechanical treatment. 
     
     
         12 : The method of  claim 9  wherein said rolling mill process is further followed by quality check of splitting tendency and other quality check. 
     
     
         13 : The method as claimed in  claim 10  wherein said process of deformation is followed by annealing the said bar to remove or reduce built-in residual stresses by a process of gradually heating and cooling. 
     
     
         14 : The method of  claim 9  wherein said rollers/gears have horizontal or vertical or inclined axes. 
     
     
         15 : The method of  claim 9  wherein said hot working temperature in case of steel is around 900° C. to 1200° C. 
     
     
         16 : The method for manufacturing of an improved bar of  claim 9  wherein said rolling mill process is followed by quenching of said bar in case of thermo mechanical treatment. 
     
     
         17 : The method of  claim 10  wherein said rolling mill process is further followed by quality check of splitting tendency and other quality check. 
     
     
         18 : The method of  claim 10  wherein said rollers/gears have horizontal or vertical or inclined axes. 
     
     
         19 : A reinforcing bar (REBAR) for reinforced concrete constructions and reinforced concrete structures comprising:
 a) steel;   b) a circular or oval or elliptical cross section; and   c) deformation of a central longitudinal axis of the bar thereby providing the bar with a uniform wave-like formation, the bar lacking sharp bends and recesses;   
       wherein the bar has a plain surface free from surface lugs, surface protrusions, surface indentations, and surface deformities; 
       whereby the bar has (i) enhanced resistance to corrosion as compared to an equivalent bar having surface deformations and lacking deformation of a central longitudinal axis and (ii) enhanced resistance to slippage at a REBAR-concrete interface as compared to an equivalent plain bar lacking deformation of a central longitudinal axis. 
     
     
         20 : The REBAR of  claim 19 , wherein the bar is of circular shape. 
     
     
         21 : The REBAR of  claim 19 , wherein the bar has an amplitude of deformation of the central longitudinal axis in a range of 1 mm to 10 mm. 
     
     
         22 : The REBAR of  claim 19 , wherein the enhanced resistance to slippage at a REBAR-concrete interface is higher compared to resistance of the equivalent plain bar lacking deformation of a central longitudinal axis. 
     
     
         23 : The REBAR of  claim 19 , wherein the steel is mild steel, medium tensile steel, or high strength steel. 
     
     
         24 : The REBAR of  claim 23 , wherein the steel is high strength steel. 
     
     
         25 : Reinforced concrete comprising the REBAR of  claim 19 .