1. objective
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 faster the development of strength.
The fineness of grinding has increased over the years. But now it has got nearly stabilized.
Different cements are ground to different fineness. The particle size fraction below 3
microns has been found to have the predominant effect on the strength at one day while
325 micron fraction has a major influence on the 28 days strength. Increase in fineness
of cement is also found to increase the drying shrinkage of concrete.

Fig. 1: Specific Surface versus Compressive Strength of Cement
Fineness of cement is tested in two ways :
(a) By sieving.
(b) By determination of specific surface (total surface area of all the particles in one gram of cement)
by airpermeability apparatus. Expressed as cm^{2}/gm or m^{2}/kg. Generally Blaine Air permeability apparatus is used.

2. apparatus required

Fig. 2: Cement
The samples of the cement shall be taken according to
the requirements of IS 3535:1986 and the relevant
standard specification for the type of cement being
tested. The representative sample of the cement selected
as above shall be thoroughly mixed before testing.


Fig. 3: Balance
Balance be capable of weighing up to 10 g to the nearest 10 mg.


Fig. 4: Sieve
It comprises a firm, durable, noncorrodible, cylindrical
frame of 150 mm to 200 mm nominal diameter and 40 mm to 100
mm depth, fitted with 90 micron mesh sieve cloth of woven
stainless steel, or other abrasionresisting and noncorrodible
metal wire.
The sieve cloth shall comply with the requirements of IS 460
(Part 1):1985 and IS 460 (Part 3):1985 and shall be free of
visible irregularities in mesh size when inspected optically by
the methods of IS 460 (Part 3):1985. A tray fitting beneath
the sieve frame and a lid fitting above it shall be provided
to avoid loss of material during sieving.


Fig. 5: Nylon Bristol Brush
For cleaning of sieve.

3. reference
IS 4031(Part 1):1996 Methods of Physical Tests for Hydraulic Cement: Determination of
Fineness by Dry Sieving (second revision). Reaffirmed May 2016
4. procedure

Agitate the sample of cement to be tested by shaking
for 2 min in a stoppered jar to disperse agglomerates.
Wait 2 min. Stir the resulting powder gently using a
clean dry rod in order to distribute the fines throughout
the cement.

Fit the tray under the sieve, weigh approximately 10 g
of cement to the nearest 0.01 g and place it on the
sieve, being careful to avoid loss. Disperse any
agglomerates. Fit the lid over the sieve. Agitate the
sieve by swirling, planetary and linear movement until
no more fine material passes through it. Remove and
weigh the residue. Express its mass as a percentage, R_{1},
of the quantity first placed in the sieve to the nearest
0.1 percent. Gently brush all the fine material off the
base of the sieve into the tray.

Repeat the whole procedure using a fresh 10 g sample to obtain R_{2}. Then calculate the
residue of the cement R as the mean of R1, and R2, as a percentage, expressed to the
nearest 0.1 percent.

When the results differ by more than 1 percent absolute, carry out a third sieving and
calculate the mean of the three values.

Check the sieve after every 100 sieving as per para 4.4.2 of IS: 4031 (Part 1)