Density of Hydraulic Cement

This test method covers the determination of the density of hydraulic cement. Its particular usefulness is in connection with the design and control of concrete mixtures. The density of hydraulic cement is defined as the mass of a unit volume of the solids. The apparatus to be used is a Le Chatelier flask, which is circular in cross-section. This flask shall be thoroughly annealed before being graduated. They shall be of sufficient thickness to ensure reasonable resistance to breakage. Each flask shall bear a permanent identification number and the stopper, if not interchangeably ground, shall bear the same number. Interchangeable ground-glass parts shall be marked on both members with the standard-taper symbol, followed by the size designation. The standard temperature shall be indicated, and the unit of capacity shall be shown by the letters “mL” placed above the highest graduation mark. Kerosene, free of water, or naphtha shall be used in the density determination. The flask shall be filled with either of the liquids mentioned to a point on the stem between the 0 and the 1-mL mark. The inside of the flask shall be dried above the level of the liquid, if necessary, after pouring. The first reading shall be recorded after the flask has been immersed in the water bath. A quantity of cement shall be introduced in small increments at the same temperature as the liquid. A vibrating apparatus may be used to accelerate the introduction of the cement into the flask and to prevent the cement from sticking to the neck. After all the cement has been introduced, the stopper shall be placed in the flask and the flask shall be rolled in an inclined position, or gently whirl it in a horizontal circle, so as to free the cement from air until no further air bubbles rise to the surface of the liquid. If a proper amount of cement has been added, the level of the liquid will be in its final position at some point of the upper series of graduations. The final reading shall be recorded after the flask has been immersed in the water bath. The difference between the first and the final readings represents the volume of liquid displaced by the mass of cement used in the test. The cement density can now be determined.