Rebar is a short form of reinforcing steel rods. It is the most important component of RCC Structure. Since concrete cannot take tensile loads, steel rebars are cast into it to carry the tensile loads.
Steel Grades of Rebars
There are many grades of rebars in the market but nowadays FE 415 and Fe 500 grades of TMT rebars are most commonly used.
Rebar Diameters
Rebars range in diameter from 4 to 50 mm. For general house constructions, bars of diameter 6 to 20 mm are used.
Rebar Weight
For any steel rebar, weight per running meter is equal to d2/162 kg. where d is diameter of the bar in mm. For example, 10 mm diamter bar will weigh 10 x 10/162 = 0.617 Kg/m.
Rebar Standards
In India, quality and properties of steel rebars are governed by the code IS:1786
Chemical Compositions of Rebars
| Constituent | Fe 415 (% Max) | Fe 500 (% Max) | Fe 550 (% Max) |
| Carbon | 0.30 | 0.30 | 0.30 |
| Sulphur | 0.060 | 0.055 | 0.055 |
| Phosphorus | 0.060 | 0.055 | 0.050 |
| Sulphur + Phosphorous | 0.11 | 0.105 | 0.10 |
Mechanical Properties of Rebars
Strength and elongation of rebars must comply with the following standards.
| Grade of Rebar | Fe 415 | Fe 500 | Fe 550 |
| Minimum Yield Stress (N/mm2) | 415 | 500 | 550 |
| Minimum Ultimate Tensile Strength (N/mm2) | 10% over Yield Stress but not less than 485 N/mm2 | 8% over Yield Stress but not less than 545 N/mm2 | 6% over Yield Stress but not less than 585 N/mm2 |
| Minimum Elongation (%) | 14.5 | 12.0 | 8.0 |
A Misconception about Rebars
“Reddish Rebars are not Good”
Sometimes, due to contact with moisture and air, rebars develop a reddish color. Reddish rebars can very well be used in construction if they are in proper physical form, weight and strength.