What is rebar?
Rebar (or reinforcing bar) is a finished long steel product, with a round or almost round cross-section, used for the reinforcement of concrete. It is also referred to as concrete reinforcing bar or corrugated rebar.
How is rebar made?
Rebar is produced by hot rolling a steel billet.
- Reheating - billet is heated in a furnace to a temperature suitable for hot rolling
- Rolling - material is passed through roughing, intermediate, and finishing stands to reduce the diameter and ascertain the required shape of the bar
- Cooling and shearing - the hot steel bar is placed on a cooling bed, before it is sheared into lengths
Rebar is supplied in straight lengths. Small diameter material can also be supplied in coil form, known as rebar-in-coil or coiled rebar. Fabricators often purchase reinforcing bar in coil form, before processing it on automated machines, that can decoil, straighten, cut and bend the steel.
During the rolling stage, the surface of the rebar is typically deformed. The surface deformations are known as ribs, lugs, protrusions or projections. They improve the bond between the steel and concrete. The product is referred to as deformed bar, debar, hot rolled ribbed bar and ribbed reinforcement bar.
Why is rebar used in concrete?
Two key forces act upon concrete – compression and tension. Compression is a force that pushes material together, whereas tension is one that pulls material apart. Concrete has strong compression strength but weak tensile strength. To compensate for this imbalance, rebar is embedded in concrete to provide the necessary tensile strength, to prevent the concrete from cracking and breaking.
What is rebar used for?
Rebar is used to reinforce a range of concrete structures, including foundations, slabs, columns and retaining walls. Reinforcing bar is used in all major segments of the construction industry, including
- Infrastructure/civil engineering - bridges, roads, tunnels and railways
- Commercial buildings - retail and high-rise office blocks
- Industrial buildings - manufacturing, warehousing and distribution facilities
- Residential buildings - single and multi-storey houses
Other types of rebar
For applications when the steel is expected to slide, smooth plain reinforcing bars, without ribs, are used. These mild steel bars tend to have a lower yield strength than deformed bar. When applications require corrosion resistance, then epoxy-coated and galvanised rebars are used.