This part of IS 4031 covers the procedure for determining the fineness of hydraulic cement using the Blaine air permeability apparatus. The test measures the specific surface area of the cement (expressed in cm²/g or m²/kg), which is a crucial parameter affecting the rate of hydration, heat evolution, and strength development of concrete.
Describes the procedure for determining the fineness of hydraulic cement by the Blaine air permeability method.
Quick Reference Values
standard porosity of compacted bed0.500 ± 0.005
testing room temperature27 ± 2 °C
testing relative humidity65 ± 5 %
filter paper porosityMedium retentive (Whatman No. 40 or equivalent)
Key Formulas
W = ρ × V × (1 - e) — Weight of sample to be tested
S = (Ss × √T × √ns) / (√Ts × √n) — Specific surface area calculation
Practical Notes
Always calibrate the Blaine apparatus using a standard reference cement of known specific surface area before testing.
Ensure the permeability cell, perforated disc, and plunger are completely clean and dry to avoid sample sticking and inaccurate volume compaction.
Place the filter paper discs correctly (one below and one above the cement bed) to prevent cement particles from clogging the perforated disc.