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  • Writer's pictureDeepesh Gupta

TMT Rebar Grades.

TMT rebars are one of the most important components of any concrete structure. They provide strength, stability and durability to the concrete. TMT stands for Thermo Mechanically Treated. This means that the steel bars are subjected to a special process that involves heating and cooling them rapidly. This process changes the microstructure of the steel and makes it more resistant to corrosion, fatigue and fire.

TMT rebars are classified into different grades according to their strength and ductility. Strength refers to how much force (in megapascals or MPa) the rebar can withstand before it starts to deform permanently (also called yield stress). Ductility refers to how much the rebar can bend without breaking. Higher strength and ductility make the rebar more suitable for earthquake-prone areas.


The grades are denoted by Fe followed by a number12. The number indicates how much stress (in MPa) the rebar can withstand before it starts to deform permanently.

The common grades of TMT rebars in India are:



  • Fe 415: This grade has a yield stress of 415 MPa. It is suitable for general purpose construction such as residential buildings, schools, hospitals etc1.

  • Fe 500: This grade has a yield stress of 500 MPa. It is stronger than Fe 415 and can be used for high-rise buildings, bridges, flyovers etc1. It also has better weldability than Fe 4153.

  • Fe 550: This grade has a yield stress of 550 MPa. It is stronger than Fe 500 and can be used for critical structures that need more strength such as dams, nuclear power plants etc1. It also has better corrosion resistance than Fe 5003.

  • Fe 600: This grade has a yield stress of 600 MPa. It is the strongest grade available and can be used for special structures that need very high strength such as missile launch pads, rocket towers etc1. It also has better fatigue resistance than Fe 5503.

Some TMT rebars also have letters after their numbers. These letters indicate some additional properties or uses of the rebar.

For example:

  • D means that the rebar has higher ductility than normal. Ductility means how much the rebar can bend without breaking. Higher ductility makes the rebar more suitable for earthquake-prone areas because it can absorb more energy during seismic vibrations without cracking or collapsing12. The minimum elongation percentage (how much the rebar can stretch before breaking) for D grade rebars is 18% whereas for normal rebars it is only 14%3.

  • S means that the rebar has higher corrosion resistance than normal. Corrosion resistance means how well the rebar can resist rusting due to moisture or chemicals. Higher corrosion resistance makes the rebar more durable and long-lasting especially in coastal areas or industrial zones where there is exposure to salt water or acidic substances2. The maximum sulphur content (whch causes rusting) for S grade rebars is 0.04% whereas for normal rebars it is up to 0.06%3.

Different standards of TMT rebars are used for different purposes depending on the design and requirements of the concrete structure.

Some examples of recommended grades for different types of structures are:

  • For residential buildings in low seismic zones, Fe 415 or Fe 415D can be used.

  • For high-rise buildings in moderate seismic zones, Fe 500 or Fe 500D can be used.

  • For critical structures in high seismic zones, Fe 550 or Fe 550D can be used.

  • For special structures in very high seismic zones, Fe 600 or Fe 600D can be used.

Apart from the strength and ductility, there are other factors that affect the quality and performance of TMT rebars such as chemical composition and bendability.

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