Determination of fineness of given sample of cement

Aim:

To determine the fineness of the given sample of cement by sieving.

Equipments Required:

• IS-90 micron sieve conforming to IS: 460-1965
• Standard balance
• Measuring jar.
• Weighing balance
• & brush.

Theory:

The fineness of cement has an important bearing on the rate of hydration and hence on the rate of gain of strength and also on the rate of evolution of heat. Finer cement offers a greater surface area for hydration and hence the faster and greater the development of strength. Increase in fineness of cement is also found to increase the drying shrinkage of concrete. Fineness of cement is tested either by sieving or by determination of specific surface by air-permeability apparatus. Specific surface is the total surface area of all the particles in one gram of cement.

Procedure:

1. Weigh accurately 100 g of cement and place it on a standard 90 micron IS sieve.
2. Break down any air-set lumps in the cement sample with fingers.
3. Continuously sieve the sample giving circular and vertical motion for a period of 15 minutes.
4. Weigh the residue left on the sieve. As per IS code the percentage residue should not exceed 10%.

Precautions:

• Air set lumps in the cement sample are to be crushed using fingers and not to be pressed with the sieve.
• Sieving shall be done holding the sieve in both hands and with gentle wrist motion.
• More or less continuous rotation of the sieve shall be carried out throughout sieving.

Observations :

Sl.No	Weight of sasmple ( gms )	Weight of residue ( gms )	Fineness ( % )
1.
2.
3.

Result:

Fineness of the given sample of cement is = __________

Viva Questions:

1. Define fineness of cement ?
2. What is the sieve size used in fineness of cement ?