# 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%