TMT Bars

Advantages & Applications”

TMT Bar

Requirement of High Strength Rebars Problems associated with High Strength Rebars Technological developments in production processes of High Strength Rebars
Comparison of different processes for production of High Strength Rebars TMT Bars Manufacturing process TMT bars vs “Quenched & Tempered” bars
Advantages & Applications International Scenario Indian Scenario

Advantages & Applications

Advantages

(i) Better Safety of structures:

because of higher Strength combined with higher Ductility.

(ii) Easy working at site:

owing to better Ductility and Bendability. Pre-welded meshes can be made to eliminate manual binding at site. Reduces construction and fabrication time.

(iii) Resists fire:

Unlike Tor steel/ CTD Reinforcement bars, TMT bars have high thermal stability. They are the preferred choice when elevated temperatures of 400-6000 C may be encountered (Chimneys, fires).

(iv) Resists corrosion:

The TMT process gives the bar superior strength and anti-corrosive properties. Controlled water-cooling prevents the formation of coarse carbides, which has been cited as the main cause for the corrosive nature of common bar.

Another reason for better corrosion resistance is the absence of surface stresses caused by the cold twisting process.
TMT Bars: resist corrosion
Figure above shows view of Platform during rainy season which clearly shows the difference between quality of CTD & TMT Bars

(v) Formability:

Due to very high elongation values and consistent properties through out the length of bar, TMT rebars have excellent workability and bendability.

(vi) Earthquake resistance:

The soft ferrite-pearlite core enables the bar to bear dynamic and seismic loading. TMT bars have high fatigue resistance to Dynamic/ Seismic loads due to its higher ductility quality. This makes them most suitable for use in earthquake prone areas.

(vii) Malleability:

TMT bars are most preferred because of their flexible nature

(viii) Fine welding features:

TMT rebars (having low carbon content) can be used for butt and other weld joints without reduction in strength at the weld joints.

(ix) Bonding strength:

External ribs running across the entire length of the TMT bar give superior bonding strength between the bar and the concrete. Fulfils Bond requirements as per IS: 456/78 and IS: 1786/85.

(x) Cost-effective:

A high tensile strength and better elongation value gives you great savings, Reduced Transportation Costs. .
The figures of these savings as given in SAIL website are reproduced below:

Saving in Steel when using SAIL TMT or SAIL TMT-HCR
(HCR: High Corrosion Resistant)

Grade ® Fe 415 Fe 500 Fe 550
Saving in steel compared to IS-2062 plain bar 40% 44% 47%
Saving in steel compared to IS-1786/ Fe 415 CTD 14% 19%

* In case of doubly reinforced beams using M15 and M20 grades of cement.

Following advertizement clip beautifully summarizes the advantages of TMT Bars in a layman’s language.

Video

[gn_media url=”https://www.youtube.com/watch?v=OWzf3rxXt0c” width=”600″ height=”400″]

Applications

TMT bars find wide applications in different spheres:

    • General purpose concrete re-enforcement structures
    • Bridges
    • Flyovers
    • Dams
    • High rise buildings
    • Industrial structures
    • Concrete roads
    • Underground structures

SAIL in its website lists out following application areas:

Specification Application Special Qualities
SAIL TMT General concrete reinforcements in high rise buildings, bridges and other concrete structures Excellent bendability, good weldability and high fatigue resistance on dynamic loading
SAIL TMT HCR*(i.e. High Corrosion Resistant) Construction exposed to coastal, marine or underground environment In addition to above this has high corrosion resistance properties

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References:
Latest developments on steel front” by Jagvir Goyal
Thermex Quenching and Tempering Technology” by R.K. Markan, the Chairman and Managing Director of H&K India
Websites of SAIL, Rajuri steel & Evcon

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