The outside surface smoothness and roughness of the reinforcing bars act as a major role for bonding with concrete.In case of smooth surface low bond is developed. On the other side in case of rough surface greater bonding is developed.
Deformed Bars
In this type of bars consists some type of extensions which act as key modes of concrete and check the slipping of bars. The deformations are generally observe along the bar at equal distances and thus the bar develops a greater bonding with concrete with controlled mechanical resistance of sliding.
Twisted Bars Or Thermo Mechanically twisted bars( TMT Bars)
This bonding may be increase by using twisted bars.Generally cold twisted bars increase the yield stress almost 50% and also save reinforcing material by 33%. The increase of stress is due to the alignment of twist.The most Suitable pitch is 90 mm to 120 mm. If the pitch is exceeds 120 mm , the stress reduces automatically.In case of twisted bars hooks are not provided generally.For that reason increase bond strength , the structure do not face any major or minor cracks.So, twisted reinforcement is very much useful and water retaining structures.
The size of the bars is used as,
4mm
5mm
6mm
8mm
10mm
12mm
16mm
20mm
22mm
25mm
32mm
36mm
40mm
45mm
50mm
etc.