CASTING OF CONCRETE CUBE AND COMPRESSION TEST ON CONCRETE CUBE
Ex.No:10
Date:
Aim
To determine the compressive strength of concrete specimens as per IS: 516 - 1959.
Apparatus required
1. Weighing balance
2. Tools and containers for mixing.
3. Tamping rod (square in cross section)
4. Automatic compression Testing machine.
5. moulds for testing cubes (150 mm side)
Significance of the test
Tests should be done at recognized ages of the test specimens, usually being 7 and 28 days.
The ages should be calculated from the time of the addition of water to the drying of
ingredients.. At least three specimens, preferably from different batches, should be taken
for testing at each selected age.
Procedure
Casting of cubes
1. Calculate the material required for preparing the concrete of given proportions
2. Mix them thoroughly in mechanical mixer until uniform colour of concrete is obtained
3. Pour concrete in the oiled with a medium viscosity oil. Fill the moulds in 2 layers each of
approximately 50mm deep and ramming 35 times each layer heavily.
4. .Finally it is finished properly and the date and batch no. are marked on the specimen.
6. Immediately after being made, they should be covered with wet mats.
7. Specimens are removed from the moulds after 24hrs and cured in water 28 days
8. After 24 hours the specimens are removed from the mould and immersed in water for
curing in a curing tank available in the Casting Yard. Then after 28 days (or 7 days/14 days),
the specimen is ready for testing.
Testing of cubes
1.The specimen is placed centrally between the bearing plates.
2.The load should be applied without shock and increased continuously at a rate of
approximately 140kg/sq.cm/minute until the resistance of the specimen to the increasing
load breaks down and no greater load can be sustained.
3. Record the maximum load applied to each cube.
4. Also note the type of failure and appearance cracks.
Result
The compressive strength of cement concrete is ________________N/mm2 in 28days
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Left side
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Observation and calculation
Mix proportion 1:1.5:3
Volume of the cube = 150mm x 150mm x 150mm
=0.003375m3
Weight of dry concrete= 1.57 x weight of wet concrete (20mm size aggregate)
Unit weight of concrete=2400kg/m3
Weight of materials taken= 1.57 x volume of slump cone x unit weight of concrete
W=………….kg
Weight of cement = x W =………….kg
Weight of fine aggregate= x W =…………… kg
Weight of coarse aggregate = x W =……………. Kg
Weight of water (ml) = W/C ratio x weight of cement
s.no Specimen Sample Size in Area Maximum Compressive Mean
no mm x (A) crushing strength=P/A in
mm x In mm2 load (P) In N/mm2 N/mm2
mm In N
1 Concrete
cube
