When does a house become a home? When the members of the household live in a safe and secure environment.
Building a structure that is inherently strong and is able to resist external forces such as earthquakes and other natural forces lays the foundation of a safe home.
Bricks, mortar, even cement, cannot provide this strength. Plain concrete, although compression-resistant, is very weak in tension and therefore is not a very good structural member by itself. However, concrete can be made extremely useful by reinforcing it with steel material like TMT bars which have the desired ductility and bond characteristics to absorb tensile forces.
Thermo Mechanically Treated (TMT) bar is a type of reinforced steel bar which undergoes an additional process during its production cycle to obtain these required characteristics. This additional process consists of Quenching and Self-Tempering.
Good quality TMT bars have high ductility which is why they can resist earthquake shocks. Their design also helps in improved bonding with cement. Strong bonding between steel bars and cement results in buildings becoming earthquake resistant.
The Indian subcontinent has a history of devastating earthquakes. Geographical data shows that almost 54% of land in India is vulnerable to earthquakes. A World Bank and United Nations report estimates that around 200 million city dwellers in India will be exposed to storms and earthquakes by 2050. Natural disasters bring huge economic losses in their wake.
Keeping all these factors in mind, a person planning to build a home should therefore give priority to purchase of TMT bars, which
Steel Authority of India Limited (SAIL), a Maharatna Central Public Sector Enterprise with the largest steel making capacity in the country, pioneered the production of TMT bars in India. SAIL has been in the forefront of the country’s infrastructural development, be it railway infrastructure, airports, bridges, dams, oil refineries, power plants or industries, and defence applications. On the safety aspect, too, SAIL has been one of the most dependable and trusted steel suppliers in the country; in fact, SAIL has been the sole supplier of rails to the Indian Railways for decades.
range of steel products in the country. The pan-India network of 4 Regional Offices, 37 Branch Sales Offices, 10 Operational Customer Contact Offices and 45 Warehouses.
SAIL has recently installed state-of-the-art new rolling mills in its major plants, among which are modern mills producing new-age TMT bars branded as SAIL SeQR (Pronounced as SAIL secure).These bars are produced through advanced manufacturing processes by the modernised integrated steel plants of SAIL using virgin iron ore from SAIL’s own mines.
For home builders, SAIL SeQR TMT bars, available in dia from 8 mm to 20 mm, promise the highest levels of safety and security at affordable prices.
Attributes | Advantages |
---|---|
High UTS/YS ratio & high ductility | Provides good plastic energy absorption leading to higher safety of structures during earthquakes/tsunamis/cyclones, etc. |
Superior bendability | Easier to bend & rebend-very good for onsite works |
Superior rib pattern | High bonding properties with concrete |
High uniform elongation | Enhances plastic energy absorption capacity High resistance to failure |
Clean steel, low Sulphur & Phosphorus levels | Enhances resistance to cold & hot shortness & imparts improved internal soundness |
SAIL SeQR TMT bars possess the unique combination of high strength and high ductility that surpasses the minimum specified level ofBIS. This combination is achieved through carefully controlled cooling which forms a hard martensitic surface and a softer ferrite pearlite inner core.
Usage of primary steel making route from virgin iron ore and secondary refining processes leads to highly clean steel with low levels of sulphur and phosphorus as well as gaseous content. (High phosphorus level makes steel brittle under cold condition leading to cracking, while high sulphur level reduces the strength under high temperature conditions). Lower levels of phosphorus and sulphur as well as use of electro magnetic stirred impart internal soundness of material thereby improving ductility in terms of higher capability for uniform elongation and better bendability.
The prominent and uniform rib pattern of SAIL SeQR TMT bars is produced through the usage of special quality CNC mechanised rings which provide capability for stronger bonding with concrete.
SAIL SeQR TMT bars are characterised by high UTS/YS ratio due to which they are capable of absorbing more energy when stressed beyond yielding point. This enables the bars to maintain their internal strength in the face of sudden occurrences such as earthquake/tsunami, etc., avoiding any catastrophic failures. Capability for higher uniform elongation also enables SAIL SeQR TMT bars to accommodate plastic deformation without necking, thereby resisting ultimate failure and providing higher safety to structures during occurrences like earthquake/tsunami/cyclones, etc.
SAIL SeQR TMT bars are bendable over lower mandrel diameter compared to specified mandrel diameters as per IS 1786-2008, Grade D specification.This allows easier bending with less effort and thus facilitates easier onsite works.
SAIL SeQR TMT bars are perfectly weldable by normal process of welding with suitable electrodes. They are also weldable without preheating, preferably with low hydrogen electrode.
SAIL SeQR TMT bars have better corrosion and fire resistance properties due to the uniform and thick tempered martensitic rim.
Element | IS 1786 : 2008 | IS 178b: 2008 | SAIL SeQR Typical Values |
---|---|---|---|
Fe 500 | Fe500D | Fe SOOD | |
Carbon (C) maximum | 0.30 | 0.25 | 0.25 |
Sulphur (S) maximum | 0.055 | 0.040 | 0.035 |
Phosphorus (P) maximum | 0.055 | 0.040 | 0.035 |
S+P maximum | 0.105 | 0.075 | 0.070 |
Parameter | IS 1786 : 2008 | IS 1786 : 2008 | SAIL SeQR Typical Values |
---|---|---|---|
Fe 500 | Fe SOOD | Fe SOOD | |
YS, MPa (minimum) | 500 | 500 | 500 |
Tensile Strength, MPa | 545 min. | 565 min. | 650 max. |
UTS/YS ratio (minimum) | 1.08 | 1.10 | 1.16 |
Total Elongation (minimum)(GL=5.65 | 12.0 | 16.0 | 18.0 |
Bend test min. mandrel dia (For nominal dia up to 20 mm) | 4d | 3d | 2d |
Rebend mandrel dia up to 10 mm Rebend mandrel dia (10 mm to 20 mm) | 5d 7d |
4d 6d (d = diameter of TMT Bar) |
3d 5d |
Size (in mm) | Weight (in kg/m) |
---|---|
8 | 0.39 |
10 | 0.62 |
12 | 0.89 |
16 | 1.58 |
20 | 2.47 |
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