Thermal Resistance of TMT bars

Thermal Resistance of TMT bars Fe415 rightsteel

Use of Thermo Mechanically Treated (TMT) reinforced bars for construction is now a standard practice. With newer technologies developing, it results in efficient constructions strategies which in turn improves the lifespan and structural integrity of the building structure. However strong the building structure claims to be, in order to for its longevity the building structure has to face several hurdles, even the natural disasters.

The Weak Point

Natural disasters are of many types, but one of the worst damages caused are by fires. Fires, they significantly affect the structural integrity of the building structure. There have been many cases reported of building collapses due to the event of a fire all over the world. The most shocking was the collapsing of the world trade centre on September 11, 2001. Even though the building was struck by aeroplanes, a popular reason for the collapsing of the structure was the loss of structural integrity caused by engulfing fires.

Due to the many advantages of steel, especially it’s tensile strength, and a similar coefficient of thermal expansion to that of concrete makes it the right choice for reinforcement. Like any other material, steel also has a weak point which is when the temperature of structural steel rises around 425°C, it begins to soften and by the time it reaches about 650°C, half the strength is lost. This condition eventually leads to structural integrity failure.

The Resistance of TMT bars

This is where the TMT reinforced steel bars come. TMT reinforced steel bars are manufactured using a unique process in which the hot rolled steel bars pass through three stages namely Quenching, Self-tempering and Annealing. This procedure results in the formation of a reinforced steel bar which has a hard martensite layer on the outside and a soft ferrite-pearlite inner core.

Due to their manufacturing process, TMT reinforced steel bars are more resistant in the event of fire spreading. The different grades of TMT steel rebars are Fe 415, Fe 500, Fe 550 and the Fe 600. Unlike normal steel bars, TMT reinforced bars can resist the loss of structural strength at higher temperatures which makes them the logical choice to use as reinforcement.


Every building structure is constructed to last long, but in order to maintain as it is, the building must be constructed using the right reinforcement steel which in turn ensures the structural integrity of the building from the forces of nature.

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