FINENESS TEST OF CEMENT
The Fineness Test of Cement is covered under ASTM C430/ASTM C150
Purpose:
The rate of hydration, strength development, and heat
evolution are all impacted by the cement's fineness. Faster strength growth
results from finer cement particles since they have a greater surface area for
hydration.
Apparatus:
- 90 µm IS Sieve: A standard sieve with 90-micron openings.
- Weighing Balance: Capable of measuring up to 100 grams with an accuracy of 0.01 grams.
- Brush: For cleaning the sieve.
Procedure:
- Sample
Preparation: Weigh approximately 100 grams of
cement accurately.
- Sieving: The cement sample should be placed on the 90 µm sieve. For
fifteen minutes, sieve the sample continuously, making sure to move the sieve
in a circular motion and keep it slightly angled.
- Weighing
Residue: After sieving, collect the residue
remaining on the sieve. Weigh this residue accurately.
- Calculation: Determine the percentage of residue retained on the sieve
using the formula:
Fineness (%) = (Weight of Residue/Original Sample Weight)×100
According
to standards, the residue should not exceed 10% by weight for ordinary Portland
cement.
Limitations:
- Manual
Sieving Errors: Because of differences in effort
and technique, manual sieving can produce inconsistencies. It is advised to use
mechanical sieving equipment for more reliable outcomes.
- Environmental
Factors: Cement particles may clump together
due to high humidity, producing unreliable results. To reduce this effect,
tests should be carried out in a controlled setting.
- Equipment
Calibration: To guarantee accuracy, weighing
scales must be calibrated on a regular basis and sieves must be maintained
properly.
The Pakistan Standards (PS) specifications, which are in line with
international standards like ASTM and BS EN, are followed by laboratories in
Pakistan. For building projects to achieve the required strength and longevity,
it is essential to keep the cement's fineness within predetermined bounds.
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