What is Specific Gravity?
Why are we calculating this value for cement?
Significance of specific gravity of cement
Experiment to determine this value
What is Specific Gravity of Cement?
Definition – Specific Gravity is just a comparison between the weight of a volume of a particular material to the weight of the same volume of water at
a specified temperature.
In Simple – It is a value to calculate whether the material is able to sink or float on water. Every material has some specific gravity. The value is normally in digits like 0.1 – 100. If the value is less than 1, then the material will float on water. If the value is greater than 1, then the material will sink.
3.15g/cc means the cement is 3.15 times heavier than the water of the same volume.
Why are we calculating this value for cement?
Normally aggregates are derived from stockpiles, which may be exposed to various conditions.
If the cement has exposed to extreme moisture content then, the specific gravity of cement will differ because of the moisture content present in the
pores.
Every material has solid particles and pores which may contain water in it. Normally our nominal mix design is based on the value of specific gravity of
cement as 3.15. The value will change over time if the cement is exposed to various weather conditions. So it is essential to determine the specific
gravity of cement before using it. This is why we are insisted on avoiding old stock cement, which may be affected by the external moisture content.
The significance of specific gravity of cement
As already said, the cement may contain lots of moisture content if it is exposed to various conditions and humidity. We all know that water cement ratio is an important factor. It is directly proportional to workability and the strength of a bonding. If the cement has already more moisture in it then, the value of water-cement ratio will actually affect the workability and strength rather than increasing it.
If the specific gravity of cement is greater than 3.19 then, the cement is either not minced finely as per the industry standard or it has more moisture content which will affect the mix and bonding. This is why you find lots of chunks while mixing old stock cement for concrete.
How to calculate cement specific gravity?
Using Le Chatelier Flask method, we can determine this value. This is an experiment conducted at the site level.
Pycnometer filled with kerosene
Objective:
To find specific gravity of cement value.
Required Apparatus and Materials
Ordinary Portland Cement
Kerosene
Le-Chatelier Flask capacity of 250 ml or Specific Gravity Bottle / Pycnometer
(100 ml)
Weighing balance with 0.1 gm accurate
Why are we using Kerosene instead of water?
To calculate specific gravity for any material, we use water. But water reacts with cement and forms calcium oxide. So that we are using Kerosene.
It doesn’t react with cement. This is why we are using 0.79 g/cc (specific gravity of kerosene) in our calculation (specific gravity of water – 1g/cc)
Test Procedure:
The Flask should be fully dry. Weigh the empty flask(W1)
Fill the cement on the bottle up to 50% of the flask (about 50gm) and weigh with its stopper (W2)
Add Kerosene to the cement up to the top of the bottle. Mix well to remove the air bubbles in it. Weigh the flask with cement and kerosene (W3)
Empty the flask. Fill the bottle with kerosene up to the top and weigh the flask (W4)
Calculation:
Specific Gravity of Cement Formula
The specific gravity of kerosene is 0.79 g/cc
Note:
The error value will be acceptable ±0.01.
The practical will be done within 30° C temperature.
conclusion
I hope that now you have the fair amount of knowledge on the Specific gravity of cement and importance of this test. If you found this article helpful
support us by sharing.
Why are we calculating this value for cement?
Significance of specific gravity of cement
Experiment to determine this value
What is Specific Gravity of Cement?
Definition – Specific Gravity is just a comparison between the weight of a volume of a particular material to the weight of the same volume of water at
a specified temperature.
In Simple – It is a value to calculate whether the material is able to sink or float on water. Every material has some specific gravity. The value is normally in digits like 0.1 – 100. If the value is less than 1, then the material will float on water. If the value is greater than 1, then the material will sink.
3.15g/cc means the cement is 3.15 times heavier than the water of the same volume.
Why are we calculating this value for cement?
Normally aggregates are derived from stockpiles, which may be exposed to various conditions.
If the cement has exposed to extreme moisture content then, the specific gravity of cement will differ because of the moisture content present in the
pores.
Every material has solid particles and pores which may contain water in it. Normally our nominal mix design is based on the value of specific gravity of
cement as 3.15. The value will change over time if the cement is exposed to various weather conditions. So it is essential to determine the specific
gravity of cement before using it. This is why we are insisted on avoiding old stock cement, which may be affected by the external moisture content.
The significance of specific gravity of cement
As already said, the cement may contain lots of moisture content if it is exposed to various conditions and humidity. We all know that water cement ratio is an important factor. It is directly proportional to workability and the strength of a bonding. If the cement has already more moisture in it then, the value of water-cement ratio will actually affect the workability and strength rather than increasing it.
If the specific gravity of cement is greater than 3.19 then, the cement is either not minced finely as per the industry standard or it has more moisture content which will affect the mix and bonding. This is why you find lots of chunks while mixing old stock cement for concrete.
How to calculate cement specific gravity?
Using Le Chatelier Flask method, we can determine this value. This is an experiment conducted at the site level.
Pycnometer filled with kerosene
Objective:
To find specific gravity of cement value.
Required Apparatus and Materials
Ordinary Portland Cement
Kerosene
Le-Chatelier Flask capacity of 250 ml or Specific Gravity Bottle / Pycnometer
(100 ml)
Weighing balance with 0.1 gm accurate
Why are we using Kerosene instead of water?
To calculate specific gravity for any material, we use water. But water reacts with cement and forms calcium oxide. So that we are using Kerosene.
It doesn’t react with cement. This is why we are using 0.79 g/cc (specific gravity of kerosene) in our calculation (specific gravity of water – 1g/cc)
Test Procedure:
The Flask should be fully dry. Weigh the empty flask(W1)
Fill the cement on the bottle up to 50% of the flask (about 50gm) and weigh with its stopper (W2)
Add Kerosene to the cement up to the top of the bottle. Mix well to remove the air bubbles in it. Weigh the flask with cement and kerosene (W3)
Empty the flask. Fill the bottle with kerosene up to the top and weigh the flask (W4)
Calculation:
Specific Gravity of Cement Formula
The specific gravity of kerosene is 0.79 g/cc
Note:
The error value will be acceptable ±0.01.
The practical will be done within 30° C temperature.
conclusion
I hope that now you have the fair amount of knowledge on the Specific gravity of cement and importance of this test. If you found this article helpful
support us by sharing.
