Different types of Steel rebars are available from different companies. Selecting the best Steel rebar for construction is important for the strength and durability of the structure. In this article, we are going to look at how to check the quality of steel rebars based on type, brand, mass, dimension, quality, length and chemical composition and how to select the best steel rebar to built RCC Houses.
1. Check the Type of Steel rebar
Steel rebars are popularly classified as follows based on their manufacturing process
1.1 TMT Bars
TMT bars are thermo-mechanical treated bars. . They are manufactured through rapid cooling process to create a tough outer surface with a relatively ductile inner core. Hence TMT bars have a better balance between strength and ductility. In the present scenario, TMT bars are widely used for their TMT bars are widely used for their following advantages.
- Superior strength.
- Good ductility and elongation.
- Better Ribs projection for bonding.
- Good weldability.
The TMT Fe500 and TMT Fe500D are two great choices for building all types of homes. Fe500D offers extra ductility. Fe500S is well suited for earthquake prone areas.
1.2 CRS TMT Bars
CRS TMT bars are corrosion resistant TMT bars. CRS TMT bars are treated to resist corrosion by epoxy coating or similar methods. They are ideal for building houses in erosive areas such as coastal areas.
1.3 HYSD Bars
HYSD bars are High Yield Strength Deformed bars. They are now replaced by TMT bars.
1.4 CTD bars
CTD bars are Cold-twisted Deformed bars. They were twisted at room temperature to increase strength. CTD bars have low strength, low ductility and they are more prone to corrosion than other bars.
2. Visual Inspection for Rust and Identification Mark
Steel rebars should be free from rust and dust. Each running meter must have their brand name, diameter and grade details such as FE 500, FE 550 D. Many branded steel bars come with a company tag.
3. Check for Uniform Mass/Weight
Steel rebars must have a homogeneous mass per unit length. Therefore, when choosing a steel brand for your construction, make sure that all steel rebars of the same diameter and the same length have the same weight.
4. Check for Minimum Mass/Weight
Check if the steel rebar has the following Minimum mass per meter according to the IS Steel Codebook.
| Nominal size of Steel rebar | Minimum Mass per meter |
|---|---|
| 4 mm | 0.099 kg/m |
| 5 mm | 0.154 kg/m |
| 6 mm | 0.222 kg/m |
| 8 mm | 0.395 kg/m |
| 10 mm | 0.617 kg/m |
| 12 mm | 0.888 kg/m |
| 16 mm | 1.58 kg/m |
| 20 mm | 2.47 kg/m |
| 25 mm | 3.85 kg/m |
| 28 mm | 4.83 kg/m |
| 32 mm | 6.31 kg/m |
| 36 mm | 7.99 kg/m |
| 40 mm | 9.86 kg/m |
The mass of the steel bar can be calculated from the popular formula d2/162. Examples are given in my other post.
- The unit weight of steel is 7850 kg/m3.
- Mass per cross-sectional area per meter is 0.007850 kg/mm2 per meter.
Sometimes there may be a slight deviation in the mass of the steel rebar, but according to the Indian Standard Steel Code book the deviations should not exceed the tolerance percentage given below.
| Nominal size of Steel Rebar | Mass Tolerance |
|---|---|
| 0-10mm | +-7 % |
| 12-16mm | +-5% |
| Above 16mm, | +-3 % |
The Test specimens taken to check the mass of the steel bar should not be less than 500 mm
5.Check for Steel Grade/Strength
Steel rebars are classified into different grades based on their strength. For example, in the Fe415D standard, “Fe” stands for iron (steel), “415” denotes the Minimum Yield strength (tensile strength) of steel bar and letter D shows the ductile property of the steel bar.
The Yield strength and Ultimate Tensile strength required for steel rebars of different grades are given below. You can check the strength and elongation property of the rebar in the labs with a help of any tensile testing machines like UTM.
| Grade of Steel | Minimum Yield Strength | Minimum Ultimate Tensile Strength | Minimum Elongation Percentage |
|---|---|---|---|
| Fe415 | 415 | 485 | 14.5% |
| Fe415D | 415 | 500 | 18% |
| Fe500 | 500 | 545 | 12% |
| Fe500D | 500 | 565 | 16% |
| Fe550 | 550 | 585 | 10% |
| Fe550D | 550 | 600 | 14.5% |
| Fe600 | 600 | 660 | 10% |
In the latest amendment of the steel codebook, new grades like Fe415S and Fe500S have been added. These grades have higher ductility than other grades and are more suitable for earthquake prone areas.
| Grade of Steel | Minimum Yield stress | Maximum Yield stress | Minimum Elongation |
|---|---|---|---|
| Fe415S | 415 | 540 | 20% |
| Fe500S | 500 | 545 | 18% |
6. Check for Length
Typically, steel rebars are provided in the form of 12-meter lengths and sometimes in the form of spirals during large construction operations. The length of the steel rebar shall not be less than 25 mm or more than 75 mm as specified in the bar specification..
7. Check for Ribs Projection
The Rib Projects on the HYST and TMT bars should not be less than the value given below. The Ribs help to create a good bond between the steel and the concrete.
| Nominal size of Deformed Steel rebar | Minimum Ribs Projection |
|---|---|
| Less than 10mm | 0.12mm |
| 12mm to 16mm | 0.15mm |
| above 16mm | 0.17mm |
8.Chemical Composition as per Indian steel codebook
| Grade of Steel | Carbon | Sulphur | Phosphorous |
|---|---|---|---|
| Fe415 | 0.3 | 0.06 | 0.06 |
| Fe415D/Fe415S | 0.25 | 0.045 | 0.045 |
| Fe500 | 0.3 | 0.055 | 0.055 |
| Fe500D/Fe500S | 0.25 | 0.40 | 0.40 |
| Fe550 | 0.3 | 0.055 | 0.055 |
| Fe550D | 0.25 | 0.40 | 0.40 |
| Fe600 | 0.30 | 0.40 | 0.40 |
9.Selection of Best Steel Rebar Brand for Construction of House
Cost is an important factor when it comes to choosing steel brands. Some cheap steels may not have the required quality, while some high quality steel may be too expensive for our needs. Listed below are some of the well known and well known good quality steel brands.
TATA Steels – TATA Tiscom, TATA Tiscom SD
Tata is the most trusted brand across India. TATA Tiscom is a high strength TMT ribbed bar. They provide good strength, ductility and elongation. TATA Tiscom SD is a super ductile steel rebar. They have a high ductile ratio of 1.5, which prevents them from breaking under sudden loads. They are best suited for buildings in seismic areas to withstand seismic loads.
JSW Steels – JSW Neo steel
JSW is another popular and trusted brand. The JSW Neosteel 550D is a high-strength TMT ripped ductile bar with good uniform mass, strength and ductility.
Other popular steel brands are Visakh Steel, Essar Steel, Camden Steel and Amman Steel.
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