Rebar

Rebar, short for reinforcing bar, is a steel bar used to reinforce concrete and masonry structures. Concrete is strong in compression but weak in tension; incorporating rebar improves tensile strength, ductility, and crack control. Rebar is typically placed in a grid or continuous runs and bonded to the surrounding concrete through surface deformations.

Most rebar is carbon steel and hot-rolled, with surface deformations (ribs) that improve bonding with concrete. Deformed bars are standard; plain bars are used in some older or specialized applications. In addition to carbon steel, other types include epoxy-coated bars for corrosion resistance in chloride environments, galvanized bars, stainless steel bars for highly corrosive conditions, and non-metallic fiber-reinforced polymer (FRP) bars as alternatives in some projects.

Rebar sizes and strength are governed by regional standards. In the United States, common grades include ASTM A615 and A615/A706, with yield strengths around 60 ksi for standard carbon steel rebar. Other regions follow standards such as BS EN or other national codes.

During construction, rebar is cut, bent, and tied or spliced to form the reinforcement layout. It is placed with a specified cover from the concrete surface to protect against corrosion. Joints may be lapped or connected with mechanical couplers; welding is generally avoided for structural rebar unless specified.

Corrosion is the major durability concern; protective measures include coatings, such as epoxy, or the use of corrosion-resistant materials. Rebar is recycled at end of life.