03/06/2025
Sometimes you go to buy reinforcement bars(Rebars) or what you call rod in the market you often get surprised when you're given different prices for thesame size of rebar/rod.
Take for instance TMT rebar(rod) of 16mm is currently #20,500 while others is around #16,500. 12mm TMT is #11,800 while other is #9,500. Often times clients feels that this differences don't matter. They prefer to go for the cheaper one.
Generally the cheaper ones are what we call HYSD rebars/rod. HYSD mean "High Yield Strength Deformed" rebars. Examples of them include IGS and YF5. High Yield Strength Deformed as a name emanates from how it's being produced.
The costlier one which is TMT is short form for Thermo-Mechanically Treated rebars. Often time when you ask sales people the difference between the two, they simply tell you that TMT is government approved while HYSD is not. But the next question you should ask is why's is TMT government approved as they rightly say.
Firstly, TMT have higher tensile strength than HYSD bars. They can withstand more loads and loading.
Secondly, TMT are more flexible unlike HYSD which are more brittle. This means that HYSD will break faster than TMT would. TMT flexural capacity can make it bend instead of breaking outrightly and in bending, it have capacity of easily returning to original form. This is why TMT is better used in earthquake or seismic prone areas.
Thirdly, TMT are less susceptible to rust and rusting where or when they're exposed to humidity, air and water. This is unlike HYSD which are easily rusted.
Fourthly, TMT have higher fire resistance than HYSD bars. So in situation of fire, TMT will remain resistant to fire for very much longer time than HYSD rebars.
Finally, at first TMT are seen to be costlier but when you realize that it can give your building longer life, then you can't say it's costlier. This is because after a number of years when HYSD rebars begins to weaken, the TMT rebars are still standing vigorously. Also while spacing your columns, you can space TMT rebar a bit longer or wider than HYSD bars. Say for instance, you can do 4m spacing for TMT in a circumstance where you did 3.6m for HYSD rebars. With this you'll save cost.
By the above logic, I'll say that TMT rebar is actually cheaper when considered together. These are the sort of things we make effort to explain to clients everyday. Some appreciate it, others may not but it is what it is.
N.B. This post is not in anyway saying you can't use HYSD rebars/rod for construction. The post is only telling you the difference between the two but power to choose remains between client and his Engineer.
... Real work, we are simply certified.
