The strength and durability of the structure depend on the properties of cement.
The fineness of the cement test is conducted to find whether the cement has been grind well or not.
What is the fineness of cement?
The fineness represents the particle size of cement. It should not be greater than 90-microns when sieved as per IS standard.
Importance of fineness of cement
- More cement coarse particles affect and reduce the rate of hydration. If the hydration rate decreases, then it impacts the strength development of concrete or mortar.
- More fineness induces dry cracks on concrete surfaces.
- Fineness cement can easily blend with other ingredients.
- The fine particles are easily mixed with the water to make the cement paste as compared to the coarser cement particle.
- Bleeding can be reduced.
- More fineness means high concrete workability and thus increases the setting time.
How it is measured?
The fineness of cement is determined by the sieving method.
It is measured by the ratio between coarse particles (which retained in 90-micron sieve analysis) to the fineness particles (which passed through the sieve analysis).
IS code – The test should be conducted as per IS code 4031 Part 1, and the test sample should be collected as per IS code 3535.
- Nylon brush
- 90-micron sieve
- Weighing balance – nearly weight 10 mg
- A quantity of 100g cement should be taken and weighed as W1.
- The sample cement should be free from lumps. Nicely stir the cement with a clean rod to spread the fineness to the whole area.
- Now place the cement sample into the 90-micron sieve and close it by the lid.
- Then shake the sieve gently for at least 15 minutes.
- Now note down the weight of retained cement particles in the sieve as W2.
Fineness of cement = (W2/W1) x 100
The test has to be done with at least three samples from the same batch. The average value is the fineness of the cement.
The ratio between the test samples should not be greater than 0.2% if else then repeat the test. The retaining cement particles in sieve should not be more than 10%.
|SI||Description||Sample 1||Sample 2||Sample 3|
|1||Weight of cement sample W1|
|2||Weight of retained cement in sieve W2|
|3||Percentage of Fineness|
The fineness ratio will differ based on the types of cement.
- Ordinary Portland cement – 10%
- Low heat cement – 5%
- Rapid hardening cement – 3 to 5%
- The cement sample should be dry.
- Accurate weighing is avoiding repeatability tests.
- Wear a hand glove when rub the sample cement by hand.
- Shake the sieve gently to prevent loss of cement or use sieve shaker
Video Courtesy – HIGHWAY GUIDE
Happy Learning 🙂