Rebar which is short for steel reinforcement bars is used to improve the tensile strength of the concrete, since concrete is very weak in tension, but is strong in compression. Steel is only used as a rebar because the elongation of steel due to high temperature (thermal expansion coefficient) nearly equals that of concrete. The major type of steel reinforcement bars is mild steel bars and deformed steel bars. The surface of mild steel bars is plain and round in shape. They are available in various sizes and are used in concrete for special purposes, such as dowels at expansion joints, for column spirals, etc. Deformed steel bars have ribs, lugs, and indentation on the surface of the bar, which reduces the major problem that is faced by mild steel bars due to slippage and excellent bonding is achieved between concrete and rebar. Deformed steel bars have two types- TMT Bars ( Thermo Mechanically Treated Bars) and High Strength deformed bars.
TMT bars are hot treated bars that are high in strength used in reinforced cement concrete (RCC) work. Strength, ductility, welding ability, bending ability, and highest quality standards at international markets are the qualities that the latest induction of the MS steel bar posses. Few characteristics of TMT rebars are better ductility and malleability, high yield strength and toughness, more bonding strength, earthquake resistance, corrosion resistance, high thermal resistance, economical and safe in use, and no loss in strength at welded joints, etc. TMT steel bars are the number one preference for coastal construction where, where extreme humidity is a big problem. The outer surface of the TMT bars is hard and the core surface is soft. Their manufacturing process includes hot rolled steel wires passed through water. This makes the surface hard and keeps the core warmer softer. TMT bars and rods are all manufactured in the same process.