1.Mild steel bars
2.Deformed steel bars
Mild steel bars (as per IS: 432, part-I -1982)
Mild steel bars are used for tensile stress of RCC (Reinforced cement concrete) slab beams etc. in reinforced cement concrete work. These steel bars are plain in surface and are round sections of diameter from 6 to 50 mm. These rods are manufactured in long lengths and can be cut quickly and be bent easily without damage.
Deformed steel bars (as per IS: 1786-1985)
As deformed bars are rods of steels provided with lugs, ribs or deformation on the surface of bar, these bars minimize slippage in concrete and increases the bond between the two materials. Deformed bars have more tensile stresses than that of mild steel plain bars. These bars can be used without end hooks. The deformation should be spaced along the bar at substantially uniform distances.
To limit cracks that may develop in reinforced concrete around mild steel bars due to stretching of bars and some lose of bond under load it is common to use deformed bars that have projecting ribs or are twisted to improve the bond with concrete. These bars are produced in sections from 6 mm to 50 mm dia.
In addition the strength of bonds of deformed bars calculated should be 40 to 80 % higher than that of plain round bars of same nominal size. And it has more tensile stress than that of plain round bars of same nominal size.
Cold twisted deformed (Ribbed or Tor Steel Bars) bars are recommended as best quality steel bars for construction work by structural Engineer.
Steel Bars for RCC Work
All finished steel bars for reinforced work should be neatly rolled to the dimension and weights as specified. They should be sound, free from cracks, surface flaws, laminations, rough, jagged and imperfect edges and other defects. It should be finished in a work manlike manner.
General precautions for steel bars in reinforcement
- Steel bars are clear, free from loose mil scales, dust and loose rust coats of paints, oil or other coatings which may destroy or reduce bond strength.
- Steel bars should be stored in such a way as to avoid distortion and to prevent deterioration and corrosion.
- Steel bars should not be clean by oily substance to remove the rust.
- The bar is bent correctly and accurately to the size and shape as shown in drawings.
- If possible, the bar of full length is used.
- Overlapping bars do not touch each other and these should be kept apart with concrete.
- The overlap if given should be staggered.
- The cranks in the bar at the end should be kept in position by using spots.
- The steel bars should not be disturbed while lying cements concrete.
- Required cover under steel bars should be given before laying the cement concrete.
- No over lap is given in the bar having a diameter more than 36 mm, if required, the bar should be welded.
Weight of Different Steel Bars
When we want to purchase Mild steel members from the market, the shopkeeper quotes the price of steel members in weight.
When any type of steel members for use in house construction is required, we calculate the length of steel member in feet or meter but we are ignorant about the weight of steel.
Here are details of weight per meter for various types of steel members:-
This will help us for estimated weight and cost. It will also help at the time of purchase to avoid pilferage in weight.
M S Steel round & square Bar
|Sr.No.||Dia of steel bar||Weight per meter|
|Round Bar||Square Bar|
|a||6 mm||0.22 Kg.||0.28 Kg|
|b||8 mm||0.39 Kg||0.50 Kg|
|c||10 mm||0.62 Kg||0.78 Kg|
|d||12 mm||0.89 Kg||1.13 Kg|
|e||16 mm||1.58 Kg||2.01 Kg|
|f||20 mm||2.46 Kg||3.14 Kg|
|g||25 mm||3.85 Kg||4.91 Kg|
|h||28 mm||4.83 Kg||6.15 Kg|
|i||32 mm||6.31 Kg||8.04 Kg|
|j||36 mm||7.99 Kg||10.17 Kg|
|k||40 mm||9.86 Kg||12.56 Kg|
|l||45 mm||12.49 Kg||15.90 Kg|
|m||50 mm||15.41 Kg||19.62 Kg|