Fineness of Cement

Experiment: To determine the fineness of cement.

Purpose: The purpose of this test is to find out the quantity of coarse material present in cement. It is an indirect test of fineness of cement.

What is fineness?

Cement is in the form of powder, which is obtained by grinding the various raw materials after calcimining. The grinding produces finer particles of cement. The degree to which the cement is ground to smaller and  smaller particles is called fineness of cement

Effect of fineness on properties if cement: 

During use of cement in structure water is mixed with cement. A chemical reaction takes place between water and cement, and it is called hydration. The strength of cement concrete or mortar develops with hydration. More the rate of hydration faster is the development of strength. This is because finer cement offers greater surface area of particles for hydration. At the same time the rate of development of heat due to hydration also increases.

Advantage of using finer cement:

The cement develops strength earlier and so formwork can be removed earlier thus reducing the cost of construction.

Disadvantage of using finer cement:

The finely ground cement is likely to deteriorate earlier due to setting because of moisture in air. Also the drying shrinkage is higher in case of finer cements.  
Methods of finding fineness of cement:
Fineness of cement is found by two methods
A) By method of dry sieving
B) By specific surface method- finding fineness of cement using Blanine's air permeability apparatus.
Though method B is more accurate it is rarely used for specific purpose.Method A is quite good for field work.