Correct option is A
The fineness of the cement is checked to test
the proper grinding of the cement which significantly influences the rate of hydration. These two methods
are used for the determination of the fineness of cement:
1) Air permeability method (Blaine):-The fineness of cement is measured as the specific surface. Specific surface is expressed as the total surface area in square meters of all the cement particles in one kilogram of cement. The higher the specific surface is, the finer cement will be.
2) Sieving method:- This method serves only to demonstrate the presence of coarse cement particles. This method is primarily suited to checking and controlling the production process. The fineness of cement is measured by sieving it on standard sieves. 100 g of cement sample is taken and air-set lumps, if any, in the sample are broken with fingers. The sample is placed on a 90 micron sieve and continuously sieved for 15 minutes. The residue should not exceed the limits specified below
