COMPRESSIVE STRENGTH TEST OF CEMENT

 COMPRESSIVE STRENGTH TEST OF CEMENT

AIM:

To find out the compressive strength of cement.



APPARATUS REQUIRED:

1. Cube mould (70.6mm X 70.6mm X 70.6mm)

2. Mixing pan

3. Trowel

4. Measuring Jar

5. Tamping Rod

6. Compressed test machine

7. Weigh balance

SAMPLE:

The cement to be used must be finely powdered material that when an adequate amount of water is added can harden both underwater and in the air resulting in a hardening of constituents through chemical interaction with water as also have a binding effect on the material that needs to be set. Formerly at 3535-1986 (Reference IS: 3535 - 1986)

PROCEDURE:

  1. The standard sand confirming to IS 650 – 1966 is taken for the test.
  2. Take 200gm of cement and 600gm of standard sand in the proportion 1:3 by weight in a pan.
  3. Mix the cement and sand in dry condition with a trowel for 1minitues and then with water until the mixture is of uniform colour.
  4. The quantity of water shall be (p/4+3) % of combined weight of cement and sand where, p is the % of water required to produce a paste of standard consistency determined earlier.
  5. The time of mixing shall be not less than 3minutes and should the time taken to obtain a uniform colour exceed more than 4mins the mixture shall be rejected.
  6. After mixing the mortar, place the mortar in the cube mould in two layers and tamp with the help of the tamping rod.
  7. The mortar shall be tamped 20times in about 8seconds to ensure elimination of entrapped air and honey combing.
  8. Place the remaining quantity of mortar in the cube mould and tamped again as specified for the first layer. Finish the top surface of the cube mould by smoothing the surface with the help of trowel
  9. Place the cube moulds in temperature of 27±2o C and 90% relative humidity for 24 hours.
  10. After 24 hours remove the cubes from the mould and immediately submerge in clean water till testing. The water in which cubes are submerged shall be renewed every seven days and maintain the temperature as 27ºC ±2ºC
  11. Take out the cubes from water just before testing. Testing should be done on their sides without any packing.
  12. The rate of loading should be 35N/mm2/minute and uniform.
  13. Test should be conducted for 3 cubes and report the average value as the test result for both 7day and 28 day compressive strength.

CALCULATION:

Compressive strength = (Breaking load)/(Area of Cross section)  N/mm2.

NOTE:

Acceptable Value – compressive strength of cement for the following grade

1. 33 grade cement – 33 N/mm²

2. 43 grade cement – 43 N/mm²

3. 53 grade cement – 53 N /mm²


REFERENCE:

IS: 4031 (PART 6) – 1988.



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