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Mild steel bars (as per IS: 432, part-I -1982)

Deformed steel bars (as per IS: 1786-1985)

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.

Various Grades of Mild Steel Bars

Reinforcement bars in accordance with standard IS No. 432 part-I can be classified into following types.   

1) Mild Steel Bars: Mild steel bars can be supplied in two grades 

     a)Mild steel bars grade-I designated as Fe 410-S or Grade 60 
     b) Mild steel bars grade-II designated as Fe-410-o or Grade 40

2) Medium Tensile Steel Bars designated as Fe- 540-w-ht or Grade 75

Physical Requirement:

Column made of steel bars

(This Picture is Contributed by "Ahmed")

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.