First of all, More than 21 popular brands of Steel available in India were tested as per IS codes by First Construction Council on the Infrastructure Quality, specially For India under GoI and State Government Missions. Only six brands of Steel passed the tests - SAIL, RINL, Tata, JSPL, JSW, and Electrotherm.
I have attached a Newspaper clipping for reference. If required, I can send you the test reports copy.
Secondly, the prominent tests on Steel are physical and chemical.
At the site, we can do some physical tests to ascertain some parameters of Steel, such as ductility, unit weight, and bending.
As per IS 1786, the unit weight of the different dia of the Steel is mentioned and its variation too. Using that data, you can check the weight of the Steel available at the site.
Further ductility, bend, and re-bend tests can also be carried out at the site. The procedure for the tests are mentioned in IS 1786.
Note: These tests carried out at the site cannot be considered as final. The tests must be carried by approved labs or institutes, and the reports given by them can be considered to gauge the quality of Steel.
The quality check of the reinforcement bars brought to the site can be performed by following inspection and tests:
Compare the manufacturer test certificate. This gives the actual properties. The manufacturer test certificate is issued for a particular lot.
Check the grade of the steel in the manufacturer certificate and look at whether it is as per the order.
Check for rust and unwanted debris on it. An undesirable amount of foreign material is not acceptable. Do check for any critical deformation or splits. A little rust is fine.
Check the brand, the grade, and the diameter on the bar.
After the above-mentioned inspection, the following tests can be performed on the site as per Indian standard code IS-1786.
Check for mass per meter run
The test involves cutting a 1m length rod from different reinforcement bundles. A minimum of 4 sample bars must be taken to conduct the test. Measure the length of each bar from four sides and take the average. Weigh the bar and record it. For the respective bar, calculate the average weight/m ( Do it for a minimum of 4 samples). Compare the result with the tabulated value of theoretical weight given in IS 1786. Check if the variation observed within the limit as per the standard code.
Bend Test and Rebend Test
In the bend test, the rebar is bend to 180 degrees as per IS 1599 in a mandrel (Mandrel specification as per IS 1786). Check for cracks or rupture on the tension side of the bent bar. If there are no such issues, the rebar has passed the bend test.
In the rebend test, the bar is bend at an angle of 135 degrees. Keep the sample in boiling water for 30 minutes (Boil to 100 degrees). After this, cool the sample. Once cooled, bend it into 157.5 degrees. Check for rupture or cracks. If there is no issue, then the bar has passed the test.
I have not seen any test being carried out at the site for testing the quality of reinforcement steel. For its quality, a lab test is required. Also the test certificate from the manufacturer can be obtained to ascertain the quality of steel.
When a lot of steel received at site, First check the Manufacturer test certificate for its actual properties. With each lot of steel, manufacturer should send a test certificate of same lot for test done at their laboratory. Check for grade of steel mention in certificate and is as per the order or not.
Steel bars may have rusting on it, do check closely to know either it is acceptable or not. Steel received should be free from any contamination like, mud, dust, oil and any other foreign material etc. Bars should not have splits and any other deformation on it.
Check for brand of steel, diameter and grade of steel embossed on steel bars.
Cut the samples of 1 meter in length, min 4 nos of bars from different bundles. Measure the length of cut bars by measuring it on at-least 4 sides and average out the length of bar. Weight the bar on weight scale and record it in register. Calculate the actual average weight per meter of bar for at-least 3 samples. Compare the result of it with theoretical weight given in IS 1786
Check the variation in weight is within limit or not as per IS specification.
After finding the results for nominal mass as satisfactory proceed further to do bend test.
Bend test should be carried out as specified in IS 1599 and using mandrels of size specified in IS 1786
Rebar sample should be bent at 180 degree as per procedure stated in IS 1599.
after this further process it to bend till 180 degree.
At site we can bend it on bar bending machine using appropriate size mandrel. sample tested bar.
After bending the bar check the surface of bar opposite to bend side (which got tension, elongated due to bending) for cracks and rupture visible to a person with normal or corrected vision.
If there is no sign of rupture and cracks, rebar meets the requirement of bend test.
Further to this a rebend test also can be done at site, if required. (IS specifies for doing but if it passes bend test, in general it will pass the rebend test too. You cand do it at side provided you have required arrangement at site for this test)
For Rebending Test: First bend the bar to including angle of 135 degree. Keep it in boiling water at 100 degree for 30 minutes. Then cool it down for some time. After cooling bent it back to including angle of 157.5 degree
The rebar should not show any rupture or cracks to a person with normal or corrected vision.
Mandrel to use for Rebend test as specified in IS 1786
Below is pic showing bend rebend test (Closely look at the direction of bending and re-bending, in order to do correct test)
After getting satisfactory results, you can approve the steel for further usage in actual construction.