This document outlines the testing method to determine the fineness of hydraulic cement utilizing the Blaine air permeability apparatus. It measures the specific surface area of the cement, a crucial property that directly influences the hydration rate, heat evolution, and strength development of concrete.
Specifies the method for determining the fineness of hydraulic cement in terms of specific surface by the Blaine air permeability apparatus.
Quick Reference Values
Standard bed porosity (e)0.500 ± 0.005
Test room temperature27 ± 2 °C
Relative humidityNot exceeding 65%
Unit of Specific Surfacem²/kg or cm²/g
Key Formulas
S = (Ss * √T) / √Ts — Specific surface area calculation (simplified for constant porosity)
W = p * V * (1 - e) — Weight of sample required to achieve standard bed porosity
Practical Notes
Ensure the manometer liquid is free-flowing and the U-tube is perfectly clean before starting the test.
Compaction of the cement bed must be uniform; uneven compaction causes air channeling and invalidates the results.
Calibration using a standard reference cement of known specific surface is mandatory whenever manometer liquid or filter paper type is changed.