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Tests Conducted To Check Quality Of Concrete

Test conducted on site for quality control

Slump test
This is a site test to determine the workability of the ready mixed concrete just before its placing to final position inside the formwork, and is always conducted by the supervisor on site. However in mid of concreting process , should the site supervisor visually finds that the green concrete becomes dry or the placement of concrete has been interrupted , a re-test on the remaining concrete should be conducted in particular of the pour for congested reinforcement area . The procedure of test in brief is as follows: –

1. Ensure the standard Slump Cone and associated equipment are clean before test and free from hardened concrete.
2. Wet the Slump Cone and drain away the superfluous water.
3. Request the mixer or concrete truck to well mix the concrete for additional 5 minutes.
4. Place the Slump Cone on one side ( i.e. not in middle ) of the base plate on leveled ground and stand with feet on the foot-pieces of cone .
5. Using a scoop and fill the cone with sampled concrete in 3 equal layers, each of about 100mm thick.
6. Compact each layer of concrete in turn exactly 25 times with a Slump Rod, allowing the rod just passes into the underlying layer.
7. While tamping the top layer, top up the cone with a slight surcharge of concrete after the tamping operation.
8. Level the top by a “sawing and rolling” motion of the Slump Rod across the cone.
9. With feet are still firmly on the foot-pieces, wipe the cone and base plate clean and remove any leaked concrete from bottom edge of the Slump Cone.
10. Leave the foot-pieces and lift the cone carefully in a vertical up motion in a few seconds time.

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11. Invert the cone on other side and next to the mound of concrete.
12. Lay the Slump Rod across the inverted cone such that it passes above the slumped concrete at its highest point.
13. Measure the distance between the underside of rod and the highest point of concrete to the nearest 5mm.
14. This reading is the amount that the sampled concrete has slumped.
15. If the concrete does not show an acceptable slump, repeat the test with another sample.
16. If the repeated test still does not show an acceptable slump, record this fact in the report, or reject that load of concrete.

Compression test
The Compression Test is a laboratory test to determine the characteristic strength of the concrete but the making of test cubes is sometimes carried out by the supervisor on site. This cube test result is very important to the acceptance of insitu concrete work since it demonstrates the strength of the design mix.
The procedure of making the test cubes is as follows: –

1. 150 mm standard cube mold is to be used for concrete mix and 100 mm standard cube mold is to be used for grout mix.
2. Arrange adequate numbers of required cube molds to site in respect with the sampling sequence for the proposed pour.
3. Make sure the apparatus and associated equipment ( see Fig 7 – 6 ) are clean before test and free from hardened concrete and superfluous water .
4. Assemble the cube mold correctly and ensure all nuts are tightened.
5. Apply a light coat of proprietary mold oil on the internal faces of the mold.
6. Place the mold on level firm ground and fill with sampled concrete to a layer of about 50 mm thick.
7. Compact the layer of concrete thoroughly by tamping the whole surface area with the Standard Tamping Bar. (Note that no less than 35 tamps / layer for 150 mm mold and no less than 25 tamps / layer for 100 mm mold).
8. Repeat Steps 5 & 6 until the mold is all filled. (Note that 3 layers to be proceeded for 150 mm mold and 2 layers for 100 mm mold).
9. Remove the surplus concrete after the mold is fully filled and trowel the top surface flush with the mold.
10. Mark the cube surface with an identification number (say simply 1, 2, 3, etc) with a nail or match stick and record these numbers in respect with the concrete truck and location of pour where the sampled concrete is obtained.

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11. Cover the cube surface with a piece of damp cloth or polythene sheeting and keep the cube in a place free from vibration for about 24 hours to allow initial set .
12. Strip off the mold pieces in about 24 hours after the respective pour is cast. Press the concrete surface with the thumb to see any denting to ensure the concrete is sufficiently hardened, or otherwise de-molding has to be delayed for one more day and this occurrence should be stated clearly in the Test Report.
13. Mark the test cube a reference number with waterproof felt pen on the molded side, in respect with the previous identification number.
14. Place the cube and submerge in a clean water bath or preferably a thermostatically controlled curing tank until it is delivered to the accredited laboratory for testing.

Checking Quality of Fine Aggregates and Bricks
For checking the quality of fine aggregates, a field test was conducted in which the sand was placed in a flask containing water. The sand was allowed to settle for some time and then after few hours the reading of the silt or other impurity layer is takenIf that reading is less than 5% of the total sand that is put in the flask, then we accept the sand but if it is more than 5% the sand is rejected. Bricks were sent to the college laboratory for testing and thereby checking the quality of the bricks used at site.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

If you have a query, you can ask a question here.

112 comments on "Tests Conducted To Check Quality Of Concrete"

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titi says:

pls i need to know about workability of concrete by cube test

OYEBOG says:

Happy new year to the founder of the website and more grace to the elbows of those who are contributing to it.
I am a people Civil Engineer and I want to say learning about this site is a blessing because it is so informative. some of my basic academic doubts are clearified

to sum it all, this is and excellent site worth knowing by all Civil engineers

thank you all

mari says:

I am a Civil Engineer. I would Like to our Engineering civil.com,Many many happy thanks to you.,

dileep naik says:

I am a civil engineer. This is a excellent and more helpful site for civil engineers.
Thanks to u………..

ran says:

what shod be the slump valu if the concrete is opc 30N

Dhrubajyoti Bhattacharya says:

For concrete slump test refer your para – 5.
Slump cone of 300mm ht shall be filled in 4 layers (not in 3 layers), each approximately one
quarter of the height of the mould. Ref Clause 5.1.4 ; IS 1199 – 1959
Dhrubajyoti Bhattacharya
Kolkata

alagar says:

i need IS 456:2000 soft copy

Er.Suresh Bali says:

I am civil Engineer.This is the perfect Web site very appropriate replies.
thanks.

subrata chakraborty says:

Please sand us of mix design m-30 7 days report & without mix design m-20 minimum and maximum compresiv strength.

subrata chakraborty says:

Please sand us of mix design m-30 7 days report & without mix design m-20 28 days report minimum and maximum compresiv strength.

mukaram choudhari says:

many many thanks to founder of this website,
it give best knowledge to any civilengg.
it is a good web for a fresher

arjuna says:

would 100mm of concrete cover be acceptable on a wall or columm.

BDC says:

We poured a concrete slab. The site supervisor took the slump and samples. He then left the samples out in the open for 48 hours. He then came back to submerge the cubes which were in the mold in water for 6 days. He removed them from the water and drove them 70 miles (20 miles of which was gravel road). He took a 7 day test and the remaining cubes were submerged in water for another 21 days, then he took a 28 day test. The concrete failed the required 3500 psi test. Would the way the supervisor handled the cubes affect the outcome of the test?

pradeep vishwakarma says:

its a good material side to regain the knowledge.i am satisfied with the site.

constructioner says:

have you got any pics? plz!

jyoti ranjan says:

dear civil engg. i want to know abt rhe sheet piling technique ?which code book has to follow for design .

Ryan says:

Can someone please help me on my college assignment, i have to write about the process that would take place if a cube test failed. going from when it was delivered to the site right back to the laboratory and try and find out where it went wrong?

many thanks

Alex says:

What are the procedures of carrying out tests on cured cube to check compressive strength?
Many thanks

ALBAN says:

REQUIRED CONCRETE STRENGTH FOR 7 DAYS

chaithika1 says:

thank u very much 4 the lessons and notes.
it was very hard me to find out any good site to get some knowledge. finally I found this site.
I’m a student and I want to get to know people like me.
I think it’s better if we can get together and talk about problems in civil engineering.

thanx

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