Procedure For Casting of Cubes and Testing
Procedure For Casting Of Cubes
The Size of the cube mould is 150mm
Step-1: – For Taking Sample and Fill Cube Mould
- Take random samples from the mix in a ghamela, while concreting.
- Pour concrete into the cubes in 3 layers.
- Compact each layer with 35 Nos. of strokes with the tamping rod.
- Finish the top surface by thapi /trowel after compaction of the last layer.
- Each specimen should be taken from different locations of the proposed concreting.
- After 24 hours, remove the specimen from the mould.
- While removing, take care to avoid breaking the edges.
- Code the cube with paint or marker. Coding should be self-explanatory, building no. and the date of casting.
- Submerge the specimen in clean, freshwater until the time of testing.
- Test 3 specimens for 7 days & 3 specimens for 28 days of curing.
Step-2: – For testing the cubes in the in-house lab of the organization, observe the following procedures-
- Check the coding & numbers of cubes received.
- Enter the details of cubes in the testing register.
- Weight the cube & note the figures in the register.
- Cube size is 150mm cube, then the volume of cube concrete is (150 x 150 x 150) = 0.003375 cubic metre
- Then Weight of the cube is not more than the volume of cube X concrete density, ( Concrete density is 2400 kg per cubic meter )
- If the Cube weight is not equal to the calculated weight, then we need to dry our cube again.
- Inform the concerned person about any damages.
- Check the dates of casting & testing for 7 & 28 days.
- Place the cube in the testing machine, so that the load is applied to the opposite side of the cube as cast, i.e., not on top & bottom.
- Record the maximum load applied to the specimen.
- Observe the appearance of concrete with the failure & note the same.
- Calculate compressive strength = ((Maximum load at failure.))/((Contact area of the cube))
- Take the average strength of specimen cubes.
- This average strength represents the strength of concrete of a particular portion of the structure.
- Prepare the test report & submit it to higher authorities.
Concrete cube strength according to days
- 7 days- 65%
- 14 days – 90 %
- 28 days – 99%