Introduction:

Thermo-Mechanically Treated bars (TMT bars) are reinforcement bars that have a hard outer core and a softer inner core. These strong and flexible steel bars are used to increase the strength of the structure. TMT bars are manufactured by passing hot rolled steel bars through icy water. The steel wire is initially passed through a rolling mill stand. Then the same rolling steel wire is passed through the water cooling system. The cold water helps to optimise pressure. This sudden quenching and change in temperature make the outer layer hard while maintaining its softer core. TMT bars gain high tensile strength and elongation points through this manufacturing process. Along with that, it also gains ductility, weldability and corrosion resistance.

What are the Advantages of TMT bars

1. More strength and ductility: TMT steel bars have higher strength and are ideal to use with concrete to make buildings tougher. The ribbed pattern of the steel bar provides extra strength in binding it with concrete. Its ductile property allows it to undergo shocks without deformation and cracks. And that’s why TMT bars can easily withstand earthquakes.
2. Fire resistance: TMT bars have high thermal stability which makes sure that the building is structurally intact even during a fire. It can easily withstand temperatures ranging from 400 to 600 degrees centigrade.
3. Corrosion resistance: TMT manufacturing process stops the building up of coarse carbides. These are elements that corrode the steel, and their prevention makes the TMT bar more durable.
4. Readily available: These are readily available as they don’t require much bending and cutting, and it saves time. Also, construction time gets reduced as wastage due to cutting and bending gets reduced. 

What are the disadvantages of TMT bars

1. High cost and weight: TMT bars are heavy and take time for transportation. Also, it is expensive and increases the overall construction cost.
2. Rust: Steel exposed to air and moist weather can lead to the formation of rust and it can reduce the cost of a bar. This rust can cause several internal pressure on the surrounding concrete and can lead to cracks in the structure.
3. Melting: TMT bars can start melting at very high temperatures and can lose their shape. This is the reason why bars are tied together and not welded.

Types of TMT bars and their diameters

TMT bars are of three major types based on their grade,

• Fe-500 grade TMT steel bars
• Fe-550 grade TMT steel bars
• TMT binding wire

The grade determines the stress level to be applied to cause a deformation in the bar’s size.

Fe-500 Grade TMT steel bars have tensile strength and ductility, and are used in the construction of buildings and bridges.

Fe-550 Grade TMT steel bars have similar properties to Fe-500 Grade, except for the fact that they have higher tensile strength. This is used in the construction of structures that are exposed to coastal, marine or underground environments.

TMT binding wire is used in tying the rebars at the joints that hold the structure together. 

TMT bars come in different sizes and diameters like 8mm, 10mm, 12mm, 16mm, 20mm, 25mm, 32mm and 36mm. And the usage of these bars depends upon their diameter.

• 8mm- 10 mm bars are used as load bearers in slab homes, like stairways.
• 12mm- 25mm bars are used to provide strength to external loads and are used in beams and columns.
• 32mm- 36mm bars are used in the construction of complex and heavy projects like dams and bridges.

Cost of TMT bars

The weight of one TMT road can be calculated using the formula (dia x dia)/ 162 x 12, where dia is the diameter of the rod. You can use L1 Supply’s TMT material calculator to estimate the amount of materials you will need for your construction project.  

Uses of TMT bars

TMT bars have their applicability across a wide variety of fields

• High-rise buildings
• Thermal and hydropower plants
• Underground metro platforms
• Bridges and flyovers
• Underwater structures
• Residential and office structures
• Dams

These were the details regarding TMT bars, usage and their prices. There are more than 10 companies that produce TMT bars in India, with Tata Steel Ltd, JSW Steel Ltd, Jindal Steel and Power Ltd and Essar Steel being the leading producers. TMT bars gained widespread popularity due to their strength and shock resisting capacity and continue to be an important aspect of construction.

Ready to explore more? Head over to our Product Page for the complete catalogue of TMT bars.