The fineness of cement is a measurement of the size of the cement particles and is represented in terms of the cement’s specific surface area.
The fineness test of cement involves passing samples of cement through a standard IS sieve. This is how the test is performed. The weight of a cement particle is calculated, and the size of the particle must be more than 90 microns.
After that, the proportion of cement particles that have been kept is computed. This property of cement is referred to as its fineness.
known about Cement test
Fineness of cement: Why is it necessary to test the fineness of cement?
When cement is combined with water, as is common knowledge, the cement will hydrate, resulting in the formation of a thin coating surrounding the particle.
This very thin layer thickens up and causes the cement particles to become more distinct. The hydration of cement proceeds at a more leisurely pace as a direct result of this factor.
On the other hand, the reaction time for smaller cement particles is substantially less than that for bigger particles.
A cement particle of diameter 1 micrometre will react completely in one day, but the reaction time for a particle with a diameter of 10 micrometres is around one month.
However, there is a drawback to having too many tiny particles in cement, and that is that it causes the cement to set very quickly, which leaves no time for mixing, handling, or laying the cement.
Therefore, in order to lengthen the amount of time it takes for cement to cure, cement must be made in a variety of various particle sizes. This property of cement is measured by the test for fineness, which is performed on the cement.
all about initial setting time of cement
Examining cement’s fineness
Aim
To evaluate the fineness of cement utilising an IS sieve with a 90 m opening in accordance with the requirements of IS: 4031 (Part 1) – 1996.
Apparatus
- 90µm IS Sieve,
- Weight Balance has a capacity of 10 mg to 100 g,
- Nylon or pure bristle brush
Procedure for testing the fineness of cement
- Get a sample of the cement, and then work it in between your fingers. The sample that is being tested for fineness should be completely lump-free.
- Take a sample of cement weighing one hundred grams and record it as the W1 weight.
- Place one hundred grams of cement in a sieve with a mesh size of ninety microns and cover it with the lid.
- Now, using your hands and moving the sieve in circular and linear motions for fifteen minutes, shake the sieve to remove any debris.
- After that, W2 is equal to the weight of the cement that passes through the sieve with a particle size of 90 microns. The formula to calculate the fineness of cement is presented in the following:
Fineness = (W2/W1) * 100
After that, compute the percentage of the cement’s weight that was kept on the sieve.
Carry out the method with each of the three distinct samples of cement and then take the average of the findings to ensure accuracy.
The calculation of cement’s degree of fineness
The fineness of cement and its value are detailed in the following table.
|
According to the IS recommendations, the standard value of fineness of cement should have a fineness that is less than 10%, or the fineness of cement should not be higher than 10%.
FAQs
How exactly is the fineness of cement determined?
Two methods are used to determine the fineness of cement: (a) Sieving. (b) Through the calculation of specific surface area (total surface area of all the particles in one gram of cement) by means of air-permeability equipment.
Why does the fineness of the cement need to be performed?
The fineness of cement has significant weight in determining the pace of hydration and, thus, the rate at which one gains strength and also the rate at which one loses heat.
