Compressive strength test

GROUP: 2

Aim

• Compressive strength of concrete cubes.

Apparatus

• Testing machine, of appropriate capacity with permissible error of 2% of the accurate result, it should be equipped with 2 hardened faces having steel plates, one of the plates shall be fitted with a ball seating in the form the position of a sphere, the center of which

Age at Testing

• Tests shall be made at 3 day, 7 day and 14 days.

No of Specimens

• The following specimens will be tested at the following days:

• 3 days – 3 cubes (150*150*150 mm)• 7 days – 3 cubes (150*150*150 mm)• 28 days – 3 cubes (150*150*150 mm) , 3

cylinder (dia:150mm height:300mm),• 3 cubes (100*100*100 mm)

Procedure• The test specimen are to be stored in the curing tank until the

time of testing. The temperature of the storage shall be from 27 ± 2°C.

• Specimens stored in water shall be tested immediately on removal from the water. The surface water and grit shall be wiped off the specimen.

• The dimensions of the specimens to the nearest 0.2mm and their weight shall be noted before testing.

• Placing the specimen in the testing machine the bearing surface of the testing machine shall be wiped clean and any loose sand or other material shall be removed from surface of the specimen, which will be in contact with the compression plates.

Procedure

• In the case of cubes the specimen shall be placed in the machine in such a manner that the load shall be applied to opposite sides of the cubes as cast, that is, not the top and the bottom of the cube.

• The axis should be carefully aligned with the center of the thrust from where the load is applied.

• No packing shall be used between the faces of the test specimen and the steel plates of the testing machine.

Procedure

• The load shall be applied without shock and increase continuously at the rate of 140kg/cm²/ min. until the resistance of the specimen to the increasing load breaks down and no greater load can be sustained by the cube.

• The maximum load applied to the specimen shall be recorded and the appearance of the concrete and any unusual feature in the type of failure shall be noted, if any

Observation TableSR NO. DAY OF

TESTINGSAMPLE NO. WT. OF

SAMPLE(KG)

Area in Cm(2) COMPRESSIVE STRENGTH(MPa)

AVG. COMPRESSIVE STRENGTH(MPa)

CUBE 7 (150*150*150) 9.01 - 26.08

3CUBE 8 (150*150*150) 9.10

-

32.82 29.13

CUBE 9 (150*150*150) 8.97 - 28.68

CUBE 4 (150*150*150) 8.91 - 39.08

7 CUBE 5 (150*150*150) 8.88 - 23.55 40.625

CUBE 6 (150*150*150) 8.91 - 42.17

CUBE 1 (150*150*150) 9.05 - 44.82

CUBE 2 (150*150*150) 9.11

-51.62 46.20

CUBE -3 (150*150*150) 9.01 - 42.62

28 CUBE-2-(100*100*100) 2.66 49.83 10.31

CUBE -3 (100*100*100) 2.64 49.71 10.14 10.30

CUBE 1 (100*100*100) 2.68 50.1 10.44

CYLINDER 3.2.1 13.72 - 17.66

CYLINDER 3.2.1 13.68 - 15.46

CYLINDER 3.2.1 13.62 - 13.57* 15.56

• Note: Indicates that the specimen was in a different curing tank *

• Indicates that specimen may have honeycombing effect (Red colour)

Failure Pattern (Cube under uniaxial compression)

Failure Pattern (Cube under uniaxial compression)

Failure Pattern (Cube under uniaxial compression)

Failure Pattern (Cube under uniaxial compression)

Failure Pattern (Cylinder under Uniaxial compression)

Failure Pattern (Cylinder under Uniaxial compression)