Theory:
Specific gravity is defined as the ratio between weight of a given volume of
material and weight of an equal volume of water. In case of cement, specific gravity is determined by use of a Le Chatelier’s flask (Figure 3). Sometimes, a specific gravity bottle may be employed to a standard Le Chatelier’s flask. To determine the specific gravity of cement, kerosene is used which does not react with cement. The specific gravity of OPC is generally around 3.15.
Objective:
Determination of specific gravity of cement using Le-Chatelier flash.
Reference:
IS 4031 (Part-11):1988.
Apparatus:
Le Chaterliers flask, weighing balance, kerosene (free from water).
Material:
Ordinary Portland cement; Water; Grease
Procedure:
1. Dry the flask carefully and fill with kerosene or naphtha to a point on the stem between zero and 1 m
2. Record the level of the liquid in the flask as initial reading.
3. Put a weighted quantity of cement (about 60 g) into the flask so that level of
kerosene rise to about 22 ml mark, care being taken to avoid splashing and to
see that cement does not adhere to the sides of the above the liquid.
4. After putting all the cement to the flask, roll the flask gently in an inclined position to expel air until no further air bubble rises to the surface of the liquid.
5. Note down the new liquid level as final reading.
Observations:
• Weight of cement used in g. (W1)
: _______
• Initial reading of flask in ml (V1)
: _______
• Final reading of flask in ml (V2)
: _______
• Volume of cement particle (V2 - V1)
: _______
• Weight of equal volume of water in g. (W2)
: _______
• Specific gravity of cement (W1/ W2)
: _______
Result and conclusion:
Specific gravity of the given cement obtained as ___________.
Precautions: (Discuss about the precautions to be taken while conducting this experiment)
Questions:
1. Why water cannot be used for determination of specific gravity of cement?
2. What are the sources of errors in this experiment?
3. If the air bubbles are not completely removed from the flask, how the results will be
affected?
4. Why is it necessary to keep the temperature of test chamber constant during this
experiment?
