TOR is the brand name for ‘Toristeg Steel Corporation’ of Luxembourg. The word ‘TOR’ came from a French man by the name of TOR who brought 1000 lbs of steel over a boat. Then later it became synonymous with Cold Twisted Deformed (CTD) steel bars.TOR steel, as high adherence steel was one of the best grades of steel used in concrete reinforcements.
TMT (stands for Thermo Mechanically Treated) Bar, also called as Reinforcing Bar or Rebar in CIVIL ENGINEERING terminology is described as a high-strength reinforcement bar with a tough outer core and soft inner core.
The processes through which both TMT bars and TOR steel are manufactured are different, giving them unique properties. However, the TMT bars have a clear advantage over TOR steel, possessing superior unique properties. This is the reason why TOR steel is less preferred.
TENSILE STRENGTH: TMT bars have a higher value of yield-strength when compared to TOR steel. For an applied load on the structural element, usage of TMT bars will result in lower steel quantity whereas the use of TOR steel results in 20% more steel quantity.
DUCTILITY: Ductility refers to the ability of any material or structural element to deform, without collapse even after reaching the failure load. TMT bars possess superior ductility when compared to TOR steel, allowing them to protect construction structures from rupture and structural collapse. Further, TMT bars also possess extraordinary strength which allows them to help a building structure acquire 20% extra strength. More importantly, all of it is built with the same amount of steel as used in conventional steel bars.
ELONGATION: Elongation refers to the ability of any material to elongate before failure. It along with yield strain/deformation plays a major role in a steel bar’s ductility; the higher the elongation, the higher will be the ductility. Also, the higher the percentage of elongation, the lesser will be the chances of damage to the construction structure. When compared to TOR Steel, TMT bars with their hard outer layer and soft inner-core can elongate in a way that makes construction structures strong and flexible, well-insured from the dangers of natural calamities, like earthquakes and so on.
BENDABILITY: It is essential to give steel bars the desired shape, such as the end-connection of beam-column joints. Though both TMT bars and TOR steel possess a good track record of bendability, TMT bars with their soft inner-core possess greater elasticity which allows them to bend more to achieve various shapes. Further, TMT bars (thanks to excellent elasticity) are equipped with better bending and re-bending properties. This makes them the easiest materials to work with that can be bent and molded into any shape during a construction project. The greater bendability of TMT bars helps construction structures to stay firm and strong even in adverse circumstances of natural calamities and other such dangers.
WELDABILITY: TMT bars with low carbon content are highly weldable when compared to TOR steel. The low-carbon ingredient in TMT bars makes them a viable choice for hassle-free welding works. Furthermore, TMT bars require no pre or post-welding treatment, which makes them easier for construction purposes. Thus, construction designers and architects can create innovative structures without compromising in any way, the quality of the structures and strength of the TMT bars.
DURABILITY: Resistance against the corrosion of steel bars is the key parameter in the durability of the construction structure. This resistance depends upon the steel bar’s chemical composition. The residual strain in TOR steel initiates a faster corrosion process than in TMT bars that do not include the twisting and stretching process. Thus, thanks to their manufacturing process and processing of raw materials, TMT bars stay highly resistant to corrosion. During any construction works, the TMT bars can stay exposed to water for a longer period without in any way getting affected. Traditional bars do not possess the anti-corrosive properties of TMT bars and hence remain vulnerable to rusting.
SEISMIC-RESISTANT: Earthquake imposes repetitive loading for a number of cycles or cyclic loading in a construction structure. The process of failure under repetitive loading is called ‘fatigue’. TMT bars are intrinsically hard and strong than TOR steel. Initially hard and strong, TOR steel shows softening behavior later which makes them vulnerable to earthquake shocks. On the other hand, with their excellent concrete bond of soft ferrite-pearlite core and reinforcement strength, TMT bars can firm up the tensile strength of construction structures. This in turn allows them to absorb a greater amount of energy released during an earthquake, and also ensure the longevity of building structures.
RUST RESISTANT: Failure in any reinforcement concrete happens due to corrosion. TOR steel corrodes in the concrete due to its high concentration of chloride ions. On the other hand, TMT bars due to their thermo-mechanical treatment are very highly rust and corrosion resistant which makes them ideally suitable for construction structures in humid and coastal areas.
FIRE-RESISTANT: TOR steel contains low thermal stability. On the other hand, TMT bars with their higher thermal stability can retain more than 80% of the ambient temperature yield strength at 300°. This helps the construction structures to stay safe and secure during fire disasters.
FLEXIBILITY: When compared to TOR steel, TMT bars are extremely flexible which allows them to endure high temperature and humidity levels. In addition, they do not crack or break even after turning and bending 180 degrees.
BONDING: TMT bars also bond better than TOR steel with cement. This is possible due to the superior bonding strength of the ribs on the surface of the TMT bars that run across the entire length. Combined with superior strength, TMT bars’ strong bonding capabilities allow them to form a strong structure with concrete or cement, whilst providing superior strength to the construction structures and increasing their longevity.
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