Concrete Compressive Strength Test Procedure
Today we are posting about Concrete Compressive Strength Test. This test is really important in construction. This Concrete Compressive Strength Test is usually done when we are pouring concrete on a structure on site. The quality control engineer will take some sample of the poured concrete then analyze it in a concrete lab. The objective of the tests are required to determine the strength of concrete and therefore its suitability for the job.
Concrete Compressive Strength Test Reference Standard.
IS : 516-1959 – Methods of tests for strength of concrete.
Concrete Compressive Strength Test Equipment.
- Compression testing machine (2000 KN)
- Curing tank/Accelerated curing tank
- Balance (0-10 Kg)
Concrete Compressive Strength Test 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.
Concrete Compressive Strength Test Calculation.
Compressive strength is calculate using the following formula :
Compressive strength (kg/cm2) = Wf / Ap
Wf = Maximum applied load just before load, (kg)
Ap = Plan area of cube mould, (mm2)
Concrete Compressive Strength Test Safety and 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.