Objective
The tests are required to determine the strength of concrete and therefore its suitability for the job.
Reference Standards
IS : 516-1959 – Methods of tests for strength of concrete.
Equipment & Apparatus
- Compression testing machine (2000 KN)
- Curing tank/Accelerated curing tank
- Balance (0-10 Kg)
Procedure
- Representative samples of concrete shall be taken and used for casting cubes 15 cm x 15 cm x 15 cm or cylindrical specimens of 15 cm dia x 30 cm long.
- The concrete shall be filled into the moulds in layers approximately 5 cm deep. It would be distributed evenly and compacted either by vibration or by hand tamping. After the top layer has been compacted, the surface of concrete shall be finished level with the top of the mould using a trowel; and covered with a glass plate to prevent evaporation.
- The specimen shall be stored at site for 24+ ½ h under damp matting or sack. After that, the samples shall be stored in clean water at 27+20C; until the time of test. The ends of all cylindrical specimens that are not plane within 0.05 mm shall be capped.
- Just prior to testing, the cylindrical specimen shall be capped with sulphur mixture comprising 3 parts sulphur to 1 part of inert filler such as fire clay.
- Specimen shall be tested immediately on removal from water and while they are still in wet condition.
- The bearing surface of the testing specimen shall be wiped clean and any loose material removed from the surface. In the case of cubes, the specimen shall be placed in the machine in such a manner that the load cube as cast, that is, not to the top and bottom.
- Align the axis of the specimen with the steel platen, do not use any packing.
- The load shall be applied slowly without shock and increased continuously at a rate of approximately 140 kg/sq.cm/min until the resistance of the specimen to the increased load breaks down and no greater load can be sustained. The maximum load applied to the specimen shall then be recorded and any unusual features noted at the time of failure brought out in the report.
Calculation
Compressive strength is calculate using the following formula
Compressive strength (kg/cm2) = Wf / Ap
Where
Wf = Maximum applied load just before load, (kg)
Ap = Plan area of cube mould, (mm2)
Safety & Precautions
- Use hand gloves, safety shoes & apron at the time of test.
- After test switch off the machine.
- Keep all the exposed metal parts greased.
- Keep the guide rods firmly fixed to the base & top plate.
- Equipment should be cleaned thoroughly before testing & after testing.
Cube test of 7 days and 28 days failed.
Additional set of cubes available was tested on the 35th day which passed.
What conclusion should be advisably reached, whether the test has failed or passed?
Is 516 strength 7 days qube and 28 days strength which is code mensoin is code
age required for pavement concrete core strength?
5.25 KN/sec is equal to 140kg/cm2/min for cube
compression testing machine for speed limit load per minute
Plz explain gypsum capping in concrete cores method & water gypsum ratio and other important thing’s about that.
Thx & best regards
G. S. Tiwari
minimum test specimen for compressive strength of concrete ?
List count of ctm 100KN capacity
what is the compressive strength of concrete cube in Dry&wet condition of M20
Do you have pdf notes of ”to check compressive strength of concrete”? Hmmmmm sir
Anyone tell me what is the compressive strength of 150mm size cubes after 60 days of curing?
Anyone tell me what is the compressive strength of 150mm size cubes after 60 days of curingcuring?
It is not easy to tell u. After conducting of test for 60days only, it is possible ok. Better u check ok. In site no one ll give permission to us. To conduct tests for 60days.
How many 28 days in 60days because M20 is strength of in 28days.
At what speed we keep our ctm machine for testing 150mmx150mmx150mm cube If answer is 5.2 Why?
140kg/sq.cm/min equals to how many KN/min ?
what its advantages?
Sir you upload evrything that is very fantastic and easy to study.
1KN equal to N?
1N equal to kg?
1KN=1000 N , 1 N= 0.101971621 KG.
if i don’t have vibration they told that I can shock the mold but i am afraid from segregation what must i do
how read the compressive test machine reading….
Dear Mr. Suryakanta
We have planned 150mm RCC, (1 cement: 1.5 Coarse sand : 3 Graded stone of 20 mm nominal size). Please confirm whether it will sustain 35 MT / Sq,Mtr.
83 ton load for cube how we will convert in n/mm2
1 ton = 10000 N
so 83 ton = 830000 N
The area off a cube in mm2 is = 150mm * 150 mm = 22500 mm2
So the strength off cube in N/mm2 = 830000/22500 = 36.9 N/mm2
140 kg/sq.cm/min convert this into tonnes/min
Bro How to Calculate Cube Test For Load to Strength ?
How to Devide 150×150 = 22500 But How to 1000 Come ?
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