REBAR (SHORT FOR REINFORCING BAR), KNOWN WHEN MASSED AS REINFORCING STEEL OR REINFORCEMENT STEEL,[1] IS A STEEL BAR USED AS A TENSION DEVICE IN REINFORCED CONCRETE AND REINFORCED MASONRY STRUCTURES TO STRENGTHEN AND AID THE CONCRETE UNDER TENSION. CONCRETE IS STRONG UNDER COMPRESSION, BUT HAS WEAK TENSILE STRENGTH. REBAR SIGNIFICANTLY INCREASES THE TENSILE STRENGTH OF THE STRUCTURE. REBAR’S SURFACE FEATURES A CONTINUOUS SERIES OF RIBS, LUGS OR INDENTATIONS TO PROMOTE A BETTER BOND WITH THE CONCRETE AND REDUCE THE RISK OF SLIPPAGE.

THE MOST COMMON TYPE OF REBAR IS CARBON STEEL, TYPICALLY CONSISTING OF HOT-ROLLED ROUND BARS WITH DEFORMATION PATTERNS EMBOSSED INTO ITS SURFACE. STEEL AND CONCRETE HAVE SIMILAR COEFFICIENTS OF THERMAL EXPANSION,[2] SO A CONCRETE STRUCTURAL MEMBER REINFORCED WITH STEEL WILL EXPERIENCE MINIMAL DIFFERENTIAL STRESS AS THE TEMPERATURE CHANGES.