AASHTO T121:2016 Standard Method of Test for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete.
1.1. This method covers determination of the density (see Note I) of freshly mixed concrete and gives formulas for calculating the yield, cement content, and the air content of the concrete. Yield is defined as the volume of concrete produced from a mixture of known quantities of the component materia is.
1.2. Nonplastic concrete, such as is commonly used in the manufacture of pipe and unit masonry, is not covered by this test method.
1.3. The values stated in either SI or inch-pound units shall be regarded separately as standard. The inch-pound units are shown in brackets. The values stated might not be exact equivalents; therefore, each system must be used independently of the other.
Note 1—Unit weight was the previous terminology used to describe the property determined by this test method, which is mass per unit volume.
1.4. The text of this test method references notes and footnotes that provide explanatory information. These notes and footnotes (excluding those in tables) shall not be considered as requirements of this test method.
4.4. Measure—A cylindrical container made of steel or other suitable metal (Note 3). The minimum capacity of the measure shall conform to the requirements of Table 1 based on the nominal size of aggregate in the concrete to be tested. All measures, except for measuring bowls of air meters, which are also used for T l2lM/T 121 tests, shall conform to the requirements of T 19M/T 19. When measuring bowls of air meters arc used, they shall conform to the requirements of T 152 and shall be standardized for volume as described in T 19M/T 19. The top rim of the air meter bowls shall be smooth and plane within 0.25 mm [0.01 in.].
Note 3—The metal should not be readily subject to attack by cement paste. However, reactive materials such as aluminum alloys may be used in instances where, as a consequence of an initial reaction, a surface film is rapidly formed that protects the metal against further corrosion.
Note 4 The top rim is satisfactorily plane if a 0.25-mm [0.01 -in.] feeler gauge cannot be inserted between the rim and a piece of 6 mm [0.25 in.] or thicker plate glass laid over the top of the measure.
Note 5 —Standardization is a critical step to ensure accurate test results when using this apparatus. Failure to perform the standardization procedures as described herein will produce inaccurate or unreliable test results.AASHTO T121 pdf download.