What is Rebar?
Rebars are steel rods which are used as reinforcement in concrete. Since concrete is strong in compression but weak in tension, so in order to make concrete strong in tension we use Steel rods as reinforcement. Steel is compatible with concrete because steel and concrete have nearly same expansion and contraction due to temperature( nearly same Thermal Coefficient).
Types of Steel Reinforcement bars
1 Mild Steel Bar : These bars have a plane surface and does not provide a good grip, that is why the are used in expansion and contraction joints in roads and runways. We don’t use these in buildings and bridges.
2 Deformed Steel Bars : All the images of the rebar you have seen is most probably deformed bars. The surface of these bars have ribs, lugs and indentations, thus these bars provides good grip and higher tensile strength
There are mainly two types of Deformed bars
1 TMT Bats(Thermo Mechanically Treated)
These bars are made by deforming and simultaneously thermally processing it like heating and cooling. The goal of the TMT process is to upgrade the properties of steel by refining its microstructure. TMT bars have superior strength, ductility, bending ability etc.
2 High Strength Deformed Bars
High Strength deformed bars are made by hot rolling followed by cold twisting. These bars are extensively used for reinforcement purposes in construction. Due to ribs or projections on the surface, these steel bars minimise slippage in concrete and increase the bond between two materials i.e. between cement concrete and steel bars
Now that you know all about rebars the next thing you should learn is how to estimate the quantity of rebar. I highly recommend you read this article: How to prepare a Bar Bending Schedule
If you are a fresher Civil Engineer looking for a job read this article: How to get a job as a fresher civil engineer