This test method covers determination of the fineness of hydraulic cement, using the Blaine air-permeability apparatus, in terms of the specific surface expressed as total surface area in square centimetres per gram, or square metres per kilogram, of cement. Two test methods are given: test method A is the reference test method using the manually operated standard Blaine apparatus, while test method B permits the use of automated apparatus that has in accordance with the qualification requirements of this test method demonstrated acceptable performance. The Blaine air-permeability apparatus consists essentially of a means of drawing a definite quantity of air through a prepared bed of cement of definite porosity. The permeability cell shall consist of a rigid cylinder, constructed of austenitic stainless steel. The disk shall be constructed of noncorroding metal, and shall fit the inside of the cell snugly. The plunger shall be constructed of austenitic stainless steel and shall fit into the cell. The filter paper disks shall be circular, with smooth edges, and shall have the same diameter as the inside of the cell. The U-tube manometer shall be constructed according to the design indicated. The manometer shall be filled to the midpoint line with a nonvolatile, nonhygroscopic liquid of low viscosity and density. The timer shall have a positive starting and stopping mechanism. The calibration of the air permeability apparatus shall be made using the standard reference material. The automated test method shall employ apparatus designed either on the principles of the Blaine air-permeability method or apparatus based on the air-permeability principles of the Lea and Nurse method. When the specific surface values determined by an automated apparatus are to be used for acceptance or rejection of cement, the method used shall comply with the qualification requirements. When standardization is required in order to achieve agreement between test method A and test method B, the apparatus shall be standardized according to the requirements prescribed.