Choosing the correct type of steel bars during the construction of your building plays a very important role in calculating its durability and longevity. There are two main types of steel bars that can be used along with reinforced concrete in the buildings. They are – mild steel bars and deformed steel bars.
Mild steel bars:
These are mainly known for their very good tensile strength when used with reinforced concrete cement. These are also referred to as plain bars as it has a very smooth surface and round cross section. These are employed only for special purposes like in the expansion joints of the dowels where the bars are expected to slide in the metals smoothly and easily. These are also used for spiral columns during construction of the roads, runways and for the contraction joints in them. However; they are not preferred much as they have a very smooth surface and thus have higher risks of slippage.
As the name itself suggests, the surface of these bars are deformed and have indentations on them. These indentations make sure that the bars offer better grip and strength and minimise slippage. When used with concrete, these also help in increasing the bond between two materials. One advantage of these deformed bars is that they have more tensile strength than the plain bars. However; care should be taken to place the deformation (indentations) at equal distances.
Why deformed bars are preferred more than the plain bars:
During the process of construction, there is a possibility of cracks developing in the reinforced concrete that is being used. These cracks appear around the surface of the mild steel bars. This can happen due to the stretching of bars under tension. Deformed bars are used instead of the mild steel bars to prevent these cracks from forming. These deformed bars are available in diameter ranging from 6mm to 50mm. Deformed steel bars also have higher tensile strength compared to the mild bars.
Important precautionary measures that must be taken during the reinforcement of steel bars:
• The surface of the steel bars being used must be free from dust, oil, rust and other elements that might threaten to reduce the strength of the bond.
• Steel bars should be stored properly such that they do not corrode.
• The steel bars must be provided with the essential cover during the process of laying the concrete cement.