How to check Quality of Reinforcement Steel bars used for Construction of RCC Structure

MOHAMMED ABDUL RAFAY

Founder Member
Staff member
Sep 7, 2017
345
153
Hyderabad
Mail sent to SAIL regarding the clarification needed:

Dear sir,
Yesterday we have received SAIL steel.
16 mm rebar itself indicating SAIL CS5.
Here our client asking what is means of CS5.
Please clarify the same to resolve the issue at site.
With regards.


Reply main from SAIL.

Dear Sir,

The CODE: CS5 is our internal code to understand the production unit, where it is being produced. It has got no link with Quality of material.
The Quality of the material can be seen from the MTC. The Brand name i.e. SAIL TMT EQR may also mentioned on the material.

This is for your clarification.

Thanking you

For Steel Authority Of India Ltd.

Good
 

Shubham Gomare

Junior Member
Mar 1, 2018
27
20
Pune
Sir,
Why there is different dia for different grades as well grade of steel. What will happen if we use the mandrel of different than mentioned. One more question is can bend steel used again by rebending them
 

abhjitsawant

Newbie
Aug 31, 2018
3
1
Thane
Quality of Reinforcement Steel Bars used for Construction of RCC Structure.
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.
View attachment 583

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.

Causes of Rusting:
Primary steel which is made from pure iron ore are likely to get rusted quicker compare to secondary steel.
Bars may get rusted due to contact with water or air and atmospheric condition.
View attachment 586
A brownish bars showing little rusting due to weathering are good for use.
Small amount of rust is good for bonding of steel and concrete.
If excessive scaling observed on the surface of bar, it should not be accepted.

Do Check for brand of steel, diameter and grade of steel embossed on steel bars.
View attachment 585

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
View attachment 587
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
View attachment 588

Rebar sample should be bent at 180 degree as per procedure stated in IS 1599.
View attachment 589
after this further process it to bend till 180 degree.
View attachment 590

At site we can bend it on bar bending machine using appropriate size mandrel.
sample tested bar.
View attachment 591

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 Rebend 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
View attachment 592
Below is pic showing bend rebend test (Closely look at the direction of bending and re-bending, in order to do correct test)
View attachment 593

After getting satisfactory results, you can approve the steel for further usage in actual construction.

Keep practice of getting steel tested from third party laboratory at 200 metric tone or at each lot received which ever is acceptable for your management.

I personally did a bend and rebend test for 25mm and 32 mm bar by witnessing it in third party laboratories.
When steel failed at my site and got passed in multiple third party test.

When i did witness test, i shocked to see many laboratories don't have the equipment's to test it, as their current set up don't allow higher diameter bars to get bend and rebend test.
Either machine reach its maximum capacity or their is chance of accident if we do it as per specification (That same laboratories gave me report stating rebar failure, this is real condition at least in my area of NABL accredited labs)

So my suggestion to all, when you get doubt on quality of steel, you personally witness the test process to understand either steel passes the test or not.

To do value addition to company and your self, you can implement following practice during unload of steel at site;
Count the number of bars received.
Record the average length of bar by doing random measurements.
Calculate the actual weight of steel received as per theoretical weight and compare it with actual total weight.
Make comparative statement showing the variation in steel weight as per brand of steel.
Show it to your management which brands are supplying overweight steel.

Overweight steel though it is as per tolerance provided in IS 1786 will cause a loss of money to your company, by understanding the which steel brand manufacture to optimum level and produce less overweight steel you can reduce the indirect loss to your company.

If i receive 25mm steel with 3% over weight, technically there is nothing wrong. Steel meets the requirement of IS 1786.
Site will suffer for 3% wastage without actually wasting steel and waste count will always add this unaccounted 3% loss as wasted by site engineer unless it is recorded.
Saving those 3% may cause gain of crores of rupees which are going directly to pocket of supplier and causing indirect costs to project due to which site engineers suffers a lot to get promotion. It may help you to get up in your career.
This is just a one example of steel, if you do correct work you can save a lot to company and get return benefit for doing such jobs.


This is something comes from experience and not told in any books (Now a days i wont read book, if any author had catched it then i am not aware about it, to write something like this author should have practical experience of project ;) )

Hope this will help you in doing better testing of steel bars and satisfaction of doing it right.

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abhjitsawant

Newbie
Aug 31, 2018
3
1
Thane
STEEL SPECIFICATION- LIST OF MANDATORY
DOCUMENT AND TEST

1) Refer IS CODE 1786:2008 for Steel
2) Steel MTC and Delivery challan should be submitted by respective Vendor during delivery of steel
to project site. No un-loading of steel will be allowed, against MTC.
3) Tare weight receipt to be checked—1st truck with steel and rechecked again after unloading of
steel.
4) After inspection of Document, field test on site will be conducted by Quality lab technician
5) Test includes Rolling Margin, Bend and Re-bend test.
6) Field test passed—Lab technician will inform the Stores/Material department
7) Field Test failed 3rd party test to be conducted
8) No steel will be allowed for construction use till 3rd party Passed report
9) For every new Steel vendor on board, 3rd party test will be conducted on priority
a. Physical Test and chemical tests—3rd Party lab Frequency
10) b. For consignment below 100 tonnes (i) under 10 mm dia, one sample for each 25 tonnes or part
thereof (ii) 10 mm to 16 mm dia one sample for each 35 tonnes or part thereof (iii) over 16 mm dia
one sample for each 45 tonnes or part thereof
11) c. For consignment over 100 tonnes (i) Under 10 mm dia, one sample for each 40 tonnes or part
thereof (ii) 10 mm to 16 mm, one sample for each 45 tonnes or part thereof (iii) over 16 mm dia,
one sample for each 50 tonnes or part thereof.
12) Tests: Selection and preparation of Test sample. All the tests pieces shall be selected by the
Quality technician or his authorized representative either- (a) From cutting of bars OR (b) If he so
desires, from any bar after it has been cut to the required or specified size and the test piece taken
from and any part of it. In neither case, the test pieces shall be detached from the bar or coil except
in the presence of the Engineer-in-Charge or his authorized representative. The test pieces
obtained in accordance with as above shall be full sections of the bars as rolled and subsequently
cold worked and shall be subjected to physical tests without any further modifications. No deduction
in size by machining or otherwise shall be permissible. No test piece shall be enacted or otherwise
subject to heat treatment. Any straightening which a test piece may require shall be done cold.
13) Tensile Test: 0.2% proof stress and percentage elongation – This shall be done as per IS 1608,
read in conjunction with IS 226.
14) RE- test: This shall be done as per IS 1786.
15) Re-bend test: This shall be done as per IS 1786
16) High strength deformed bars & wires shall conform to IS 1786. The physical properties for all sizes
of steel bars are mentioned in Table 5.2
17) Chemical composition of reinforcement bars shall be as per Table 5.3
18) Mild steel is not recommended for the use in structures located in earthquake zone subjected to
severe damage and for structures subjected to dynamic loading.
19) Nominal mass/weight : The tolerance on mass/ weight for round and square bars shall be the
percentage given in Table 5.1 of the mass/ weight calculated on the basis that the masses of the
bar/ wire of nominal diameter and of density 7.85 kg/ cm3 or 0.00785 kg/mm3 .
20) Thermo Mechanically treated reinforcement bars: (a) There is no BIS code for TMT bars. The
available code BIS 1786 pertains to HSD Bars. Therefore there should be no stipulation that TMT
bars should conform to relevant BIS code.
(b) The TMT bars are being produced under valid licence from either of the firms namely Tempcore,
Thermex Evcon Turbo & Turbo Quench. These firms have acquired patents and are giving licence
to various producers to produce TMT Bars.
(c) The TMT bars shall conform to IS 1786 pertaining to Fe 415 D or Fe 500 D or Fe grade of steel
as specified.
(d) In design and construction of reinforced concrete building in seismic zone III and above, steel
reinforcement of Grade Fe 415 D shall be used. However, high strength deformed steel bars,
produced by thermomechanical treatment process of grade Fe 415, Fe 500 and Fe 550 having
elongation more than 14.5. % and conform to other requirements of Fe 415 D, Fe 500 D and Fe
550 D respectively of IS 1786 may also be used for reinforcement. In future, latest provision of IS
456 and IS 13920 or any other relevant code as modified from time to time shall be applicable.