To determine the fineness of cement by dry sieving as per IS: 4031 (Part 1) – 1996.
The fineness of cement is measured by sieving it through a standard sieve. The proportion of cement, the grain sizes of which, is larger than the specified mesh size is thus determined.
1) 90μm IS Sieve
2) Balance capable of weighing 10 g to the nearest 10 mg
3) A nylon or pure bristle brush, preferably with 25 to 40 mm bristle, for cleaning the sieve.
- Weigh approximately 10g of cement to the nearest 0.01g and place it on the sieve.
- Agitate the sieve by swirling, planetary and linear movements, until no more fine material passes through it.
- Weigh the residue and express its mass as a percentage R1, of the quantity first placed on the sieve to the nearest 0.1 percent.
- Gently brush all the fine material off the base of the sieve.
- Repeat the whole procedure using a fresh 10g sample to obtain R2. Then calculate 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.
REPORTING OF RESULTS:
Report the value of R, to the nearest 0.1 percent, as the residue on the 90μm sieve.
Fineness of cement affects hydration rate hence the rate of strength gain. The smaller the particle size, the greater the surface area-to-volume ratio, and thus, the more area available for water-cement interaction per unit volume. Therefore finer cement reacts faster with water and the rate of development of strength and corresponding heat of hydration is high.
Fineness test is used to check the proper grinding of cement and measures the surface area of the cement particles per unit mass.
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