What is Specific Gravity of Cement?
Specific
gravity of a material is defined as the ratio between weight of a given volume
of material and weight of an equal volume of water. Therefore, specific
gravity of cement is the ratio of weight of a given volume of cement with
weight of an equal volume of water at a specified temperature.
Specific
gravity of a material is a dimensionless quantity.
Why is Specific Gravity Test of Cement Important?
Specific gravity is
an important property of cement being related to its density
and viscosity. It is one of the factor to determine the density of cement. Moreover,
density of the cement and other materials is one of the vital parameter, which
determines the design of the concrete. If the specific gravity of cement is
more than 3.19 then it has more moisture content, which will affect the mix and
bonding.
When water is added
to the cement then the hardening of the
cement starts. Once the cement hydrated with water, it becomes
useless. So kerosene is used to determine the specific gravity of cement.
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Specific Gravity of Cement by as per IS: 4031 Part-11 (1988)
Hi friends, you are welcomed in Civil
Allied Gyan. Here I have explained about determination of
the specific gravity of cement. Read definition,
apparatus, IS code, test procedure, observations, formula,result, lab report
about specific gravity of cement by Le-Chatelier method.
IS Code for Specific Gravity of Cement Test:-
IS:
4031 (Part 11)-1988, Methods of physical tests for Hydraulic cement for
determination of specific gravity of cement
Apparatus Required For Specific Gravity Test of Cement Test by Le-Chatelier Flask:-
- Ordinary Portland Cement (OPC)
- Le-Chatelier Flask of 250 ml or Specific Gravity Bottle / Pycnometer of 100 ml
- Weighing Balance with 0.1g accuracy
- Kerosene (free from water)
- Glass Funnel
- A Shallow Tray
- Constant Temperature Water Bath
Procedure for Specific Gravity Test of Cement by Le-Chatelier Method:-
- Dry and
clean the specific gravity bottle and weigh it with the stopper (W₁).
- Fill
the specific gravity bottle with cement paste sample at least half of the
bottle and weigh with stopper (W₂).
- Fill
the specific gravity bottle containing the cement sample, with kerosene oil (free
of water) placing the stopper and weigh it (W₃).
Until doing this, do not allow any air bubbles to remain in the specific
gravity bottle.
- After weighing the specific gravity bottle, the bottle will be cleaned and dried again.
- Then
fill the specific gravity bottle with fresh kerosene oil and weigh it with
stopper (W₄).
- Remove the kerosene oil from the specific gravity bottle and fill it with full of fresh water and measure the weight of bottle along with stopper (W₅).
- All the above weighing should be done at the room temperature of 26°C to 28°C.
We can use Le-Chatelier Flask instead of specific gravity bottle.
Observations:-
Description
of item
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Trial
1
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Trial
2
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Weight
of empty bottle (W₁ g)
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Weight
of bottle + Cement ( W₂ g)
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Weight
of Specific gravity bottle + Cement + Kerosene ( W₃ g)
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Weight
of bottle + Full Kerosene( W₄ g)
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Weight
of bottle + Full Water ( W₅ g)
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Calculations:-
Formula for Specific gravity of cement:
The specific gravity of kerosene is 0.79.
Therefore, also
Results:-
Specific
gravity of Cement (Given Sample) =-----------------------
Report:-
Two tests will be carried out and their average value is reported. If the difference between the two values differs by more than
0.03, the test shall be repeated.
Safety and Precautions While Testing:
- Clean the apparatus thoroughly before testing and after testing.
- The test should be performed away from vibrations and other disturbances.
- Wear helmet, shoes and hand gloves during the test.
- While pouring cement in the specific gravity bottle (or Le-Chatelier flask), care should be taken to avoid splashing and cement should not adhere to the inside of the flask above the liquid.
- The kerosene oil or Naphtha should be completely free from water.
- The specific gravity bottle should be kept in a constant temperature water bath sufficiently long to ensure same temperature before each weighing is made.
- All air bubbles will be eliminated in filling the apparatus and inserting the stopper.
- Duplicate results of specific gravity of cement should agree within 0.01.
Standard
Value of Specific Gravity of Cement:-
The value for specific gravity of Ordinary Portland
Cement (OPC) is nearly 3.15 while the specific gravity value of Portland-Blast-Furnace-Slag
and Portland-Pozzolan cements is nearly 2.90.
− As
per Portland cement Association (PCA 1988) and Design & Control of Concrete
Mixtures.
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