What is the Density Test of Hydraulic Cement?


Density of a material is the ratio of the mass of material and the volume of material of same mass. By using Le-Chatelier Flask apparatus, we conduct density test of hydraulic cement. Density of the cement gives the weight of cement of a specified volume. It is used to calculate the specific gravity of cement.

The density test of hydraulic cement is conducted as per IS 4031 (Part 11)-1988.


Density of the cement and other material is one of the vital parameter, which determines the design of the concrete. Since concrete mix proposition is done based on the weigh batching not on volumetric so density is a most important factor of cement. This explain that how important the density test of hydraulic cement is.

Density Test of Hydraulic Cement to Calculate Specific Gravity

Density Test of Hydraulic Cement to Calculate Specific Gravity, IS 4031 (Part 11)-1988


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IS: 4031 (Part 11)-1988, Methods of physical tests for Hydraulic cement for determination of specific gravity of cement


  1. Ordinary Portland Cement (OPC)
  2. Le-Chatelier Flask of 250 ml or Specific Gravity Bottle / Pycnometer of 100 ml
  3. Weighing Balance with 0.1g accuracy
  4. Heavy Rubber Pad about 12 in. × 12 in.
  5. Kerosene (free of water having a specific gravity not less than 0.731)
  6. Glass Funnel
  7. Constant Temperature Water Bath

Density Test of Hydraulic Cement to Calculate Specific Gravity

Temperature: The temperature of the laboratory will be maintained at 25ºC to 29ºC.


Procedure for Density Test of Hydraulic Cement by Le-Chatelier Method:-

  1. Take the representative sample of the cement as per IS: 3535-1986 and thoroughly mix before testing.
  2. Dry the Le-Chatelier flask and fill with kerosene oil or Naphtha to a point on the stem between the 0 and 1ml mark.
  3. After pouring, dry the inside of the flask above the level of the kerosene oil or Naphtha if necessary.
  4. Immerse the Le-Chatelier flask in a constant temperature water bath maintained at room temperature for a sufficient interval before making either of the readings so as to avoid variations greater than 0.2°C in the temperature of the liquid (kerosene or naphtha) in the flask.
  5. Record the level of the kerosene oil in the flask as initial height reading.
  6. Introduce a weighed quantity of cement (about 64 g for Portland cement) into the flask at the same temperature as the liquid so that the level of kerosene rises to about say 22 ml mark.
  7. Splashing should be avoided and cement should not be allowed to adhere to the insides of the flask above the liquid (kerosene or naphtha).
  8. Use a vibrating apparatus to accelerate the introduction of the cement into the flask and to prevent the cement from sticking to the neck.
  9. After all the cement has been introduced, insert the stopper into the flask and roll the flask gently in an inclined position to free the cement from air until no further air bubble rises to the surface of the liquid (kerosene or naphtha).
  10. If a proper amount of cement has been added, the level of the liquid (kerosene or naphtha) will be in its final position at some point of the upper series of graduations.
  11. Keep the Le-Chatelier flask again in constant temperature water bath maintained at room temperature for a sufficient interval before making either of the readings so as to avoid variations greater than 0.2°C in the temperature of the liquid (kerosene or naphtha) in the flask.
  12. Note down the new liquid (kerosene oil or naphtha) level in the flask as final height reading.

All readings should be checked until they are constant to ensure that the contents of the flask have reached the temperature of the water bath.


Observations:-
  • Mass of cement (used in the test) = …….. g
  • Initial height reading = ……. cm³
  • Final height reading = ……. cm³
  • Displaced volume = Initial reading Final reading = ……. cm³


Table: Recorded readings of the density test of hydraulic cement
Density Test of Hydraulic Cement to Calculate Specific Gravity


Calculations:-
The difference between the initial and final readings represents the volume of liquid (kerosene oil or naphtha) displaced by the mass of cement used in test.

Formula for Density Test of Hydraulic Cement:-
Density Test of Hydraulic Cement to Calculate Specific Gravity

Results:-
Density of Hydraulic Cement (Given Sample) =-----------------------

Report:-
The average value of two tests shall be reported to the second place of decimal.

If the difference between the two values of trails differs by more than 0.03, the test shall be repeated. Run three additional tests until a pair of valves are obtained within 0.03 g/cm³.


Safety and Precautions While Testing:
  1. Clean the apparatus thoroughly before testing and after testing.
  2. The test should be performed away from vibrations and other disturbances.
  3. Wear helmet, shoes and hand gloves during the test.
  4. While pouring cement in the Le-Chatelier flask, care should be taken to avoid splashing and cement should not adhere to the inside of the flask above the liquid.
  5. The kerosene oil or Naphtha should be completely free from water.
  6. The specific gravity bottle should be kept in a constant temperature water bath sufficiently long to ensure same temperature before each weighing is made.
  7. All air bubbles will be eliminated in filling the apparatus and inserting the stopper.
  8. Use a rubber pad on the tabletop when filling or rolling the flask.
  9. Before the cement has been added to the flask, a loose-fitting lead-ring weight around the stem of the flask will be helpful in holding the flask in an up-right position in the water bath or the flask may be held in the water bath by a burette clamp.
  10. For cleaning of Le-Chatelier flasks, acid cleaning is not effective in removing any deposition of silicic acid gel. Therefore, satisfactorily clean the Le-Chatelier flask by using warm sodium carbonate solution.


Standard Value of Density of Hydraulic Cement:-
The value for density of hydraulic cement is 2.8 g/cm³ (gram per cubic centimeter). The relative density (specific gravity) of hydraulic cement is 3150 kg/m³, which is equal to 3.15 grams/ml or 3.15 g/cm³ or 3.15 kg/liter. This is why we take the value for specific gravity of cement 3.15.

The bulk density of cement is nearly 1.14. This means the bulk of cement (solid particles surrounded by air voids) has a density of about 1140 kg/m³, which is equal to 1.14 grams/ml or 1.14 g/cm³. Standard density of one cement bag is equal to 1.14 grams/ml or 1.14 g/cm³ or 1440 kg/m³


Significance of Specific Gravity of Cement:-
Density of the cement and other material is one of the vital parameter, which determines the design of the concrete. Since concrete mix proposition is done based on the weigh batching not on volumetric so density is a most important factor of cement.