When considering any form of construction, whether commercial or private, checking for the quality of the steel bars is a very important factor. Since steel bars are the initial foundation of any structure, they not only provide strength and durability to it but also save it from any kind of natural calamity.
To avoid future mishaps, it is wise to choose a TMT bar of greater quality and a reputable brand while going for the construction of any property. There are a few grounds that you might consider before purchasing a quality steel bar along with this, a few important tests are also performed that a TMT bar must pass to demonstrate its high quality, which is outlined here.
First and the foremost point is to ask for a mill test certificate (MTC), from the wholesaler.
A mill test certificate(MTC) or mill test report(MTR), is issued by a manufacturer to certify the chemical & mechanical features of a product, and its compliance with the applicable norms and technical specifications.
An MTC report contains the following information :
- Product name and dimensions(grade & diameter in case of a TMT bar)
- Quantity covered by the certificate (ex. Metric tons)
- Final test result
- Dimensional measurements, to check compliance with allowed tolerances(ex, for steel bars: diameter, wall thickness, length, straightness).
- Material grade & applicable specification, including results of chemical and mechanical tests.
- Results of any additional tests like hydrostatic, ultrasounds, hardness impact test, etc.
Match the received product with the standards mentioned in the MTC report.
Thorough physical examination of the product received.
- Check the length of the bars using measuring tapes.
- Check the weight of the TMT bar according to the IS standard code, for ex: In IS standard you can find the ideal weight of approx. 1m TMT bar. If the weight is according to the IS standard code, the quality of the received TMT bar is fine.
- Check the color of the TMT bar, it should be steel grey( yellow or a rusty brown color is a depiction of a corroded metal), any slight or noticeable difference in the color could affect the quality of the TMT bar.
Bend test: In the bend test, the steel bar is bent at 135 degrees, then is checked for any kind of cracks or rupture on the tension side of the bent bar, if there are no such issues, the rebar has passed the bend test.
Rebend test: Keep the sample in boiling water for 30 min(boil to 100 degrees). After this, cool the sample, once cooled, bend it to 157.5 degrees, then check it from the tension side if no cracks are found the bar is said to have passed the test.
The above-mentioned tests will help verify a product whether it is of the highest quality or not. To find all the product specifications in one place you can look for the details on the MTC report and cross-check the details if they are in accordance with the standard mentioned in IS 1786.
Other grounds that you must consider while buying a steel bar are:• ISI Mark – always look for the standard Indian standard mark, mentioned on the bar. • Seismic zone- most of the areas which lie in the high seismic zones are prone to frequent earthquakes and other natural calamities, construction in such red zone areas should be done using high-grade and highly ductile TMT steel bars. • Ribs on steel bars- ribs are provided on the TMT bar to support bonding. It is often advised to buy TMT with transverse ribs. While using TMT in slab construction requires a steel bar to be bent. During Bending, do not bend it along the longitudinal ribs. Also, purchasing TMT bars with x-ribs is not advisable. • Length of steel bar- primary steel bar used in construction should always be 12m in length.
Secondary steel bars whose business is not flourishing often use duplicate bars in the market instead of the primary bars, this is done to maintain the factory cost and minimize losses.
Before choosing to purchase a TMT bar, visit the company website if it’s there. Check their distributors and dealer networks and evaluate their product category thoroughly. This might provide you an idea about the difference between a real and duplicate TMT bar.