SPECIFIC GRAVITY/DENSITY OF HYDRAULIC CEMENT (IS:4031-Part 11-1988)

Overview

Specific gravity is defined as the ratio between the weight of a given volume of cement and weight of an equal volume of water.

Apparatus

Measuring Instruments

NAME CAPACITY / RANGE / SIZE ACCURACY / LEAST COUNT
Lechatelier flask
Balance
Water bath

Other Apparatus

 Tray
Le chatelier flask
Le chatelier flask

Environmental Conditions

Temp
Relative humidity

Test Procedure

  1. Dry the Le-chatelier flask and fill with kerosene oil or Naptha to a point on the stem between 0 and 1 ml.
  2. Dry the inside of the flask above the level of the liquid.
  3. Immerse the flask in a constant temp water bath maintained at room temp for sufficient time.
  4. Record the level of the kerosene oil in the flask as initial reading.
  5. Introduce about 60 g of cement into the flask so that the level of kerosene rises to about say 22 ml mark. Splashing should be avoided and cement should not be allowed to adhere to the sides of the flask above the liquid.
  6. Insert the glass nipple into the flask and roll it gently in an inclined position to free the cement from air until no further air bubble rises to the surface of the liquid.
  7. Keep the flask again in constant temp water bath and note down the new liquid level as final reading.

Calculation

The difference between the first and final readings represents the volume of liquid displaced by the mass of cement used in test.

The density is calculated as per the below mentioned formula to the second place of decimal.

cement sp gravity 1

  • Note ::Two tests shall be carried out and the average is reported. If the difference between the two values differs by more than 0.03, the test shall be repeated.

Precautions

  • While pouring cement in the Lechatelier flask, care should be taken to avoid splashing and cement should not adhere to the inside of the flask above the liquid.
  • The kerosene or Naptha should be completely free from water.

Technical Discussions

  • The test for finding the specific gravity of Portland cement was originally considered to be of value in detecting adulteration and under burning, but is no longer thought to be of much importance in view of the fact that other tests  lead to more definite conclusions.

Test Standard Reference

  • IS:4031(Pat 11):1988-Methods of physical tests for hydraulic cement (Determination of density)
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