Standards for the specification of rebar are set out in: BS 4449: 2005 Steel for the reinforcement of concrete. Weldable reinforcing steel. Bar, coil and decoiled product.
Rebar is commonly manufactured using mild or high yield steel of grade 250 or 250 N/mm2 characteristic tensile strength. The constituents of both of these grades are around 99% iron, along with manganese, carbon, sulphur and phosphorous. The quality and grade of steel is dependent on the proportion of carbon. Mild cold-worked steel contains around 0.25% carbon, whereas high yield hot-rolled steel contains around 0.40%.
Bars can be manufactured in various forms:
4. Stretched, twisted and ribbed.
5. Ribbed and twisted.
Steel reinforcement mesh or fabric can be produced in different formats following BS 4483: Steel fabric for the reinforcement of concrete.
The standard sheet size is 4.8 m long x 2.4 m wide. It is formed by interweaving or electronically-welding the wires so that it will withstand normal handling. It can be produced in different ways for different applications:
- Square mesh: Mesh size of 200 mm x 200 mm, weight range of 1.54-6.16 kg/sq. m. Typically used for floor slabs.
- Rectangular mesh: Mesh size of 200 mm x 100 mm, weight range of 3.05-10.9 kg/sq. m. Typically used for floor slabs.
- Long mesh: Mesh size of 100 mm x 400 mm, weight range of 2.61-6.72 kg/sq. m. Typically used for road and pavement construction.
- Wrapping mesh: Mesh size of 100 mm x 100 mm. Typically used in suspended or ground supported slabs.
Reinforcement in concrete mainly bears tensile stress. Deformed reinforcement, due to the role of the rib, and concrete has a greater bondability, so it can better bear the role of external force. Steel bar is widely used in all kinds of building structures. Especially large, heavy, light thin-walled, and high-rise building structures.