ASTM C204

Fineness of Hydraulic Cement by Air-Permeability Apparatus

Applicability: Applies to portland cement, blended hydraulic cements, and other hydraulic cementitious materials where fineness is a specification or quality control parameter. Used in cement manufacturing, quality assurance testing, and construction materials laboratories to verify compliance with ASTM C150, C595, C1157, and similar specifications that require Blaine fineness reporting.

Purpose: Determines the fineness of hydraulic cement by measuring the specific surface area in cm²/g using the Blaine air-permeability apparatus. Air is drawn through a compacted cement bed at a defined porosity, and the time required for a fixed volume of air to pass through is compared against a calibrated reference. The resulting Blaine fineness value characterizes particle size distribution indirectly and is used to predict hydration rate, strength gain, and workability of cementitious systems.