1.2.1 with up to 35 %, by dry mass, passing a No. 200 (75-μm) sieve if the portion passing the No. 40 (425-μm) sieve is nonplastic;

1.2.2 with up to 15 %, by dry mass, passing a No. 200 (75-μm) sieve if the portion passing the No. 40 (425-μm) sieve exhibits plastic behavior.

1.3.1 less than 30 %, by dry mass, is retained on the ³/₄-in. (19.0-mm) sieve, or in which

1.3.2 100 %, by dry mass, passes the 2-in. (50-mm) sieve.

1.5.1 Method 1A—Using saturated material and a 6-in. (152.4-mm) diameter mold; applicable for materials with maximum particle size of ³/₄-in. (19-mm) or less, or with 30 % or less, by dry mass, retained on the ³/₄-in. (19-mm) sieve.

1.5.2 Method 1B—Using saturated material and an 11-in. (279.4-mm) diameter mold; applicable for materials with maximum particle size of 2-in. (50-mm) or less

1.5.3 Method 2A—Using oven-dry material and a 6-in. (152.4-mm) diameter mold; applicable for materials with maximum particle size of ³/₄-in. (19-mm) or less, or with 30 % or less, by dry mass, retained on the ³/₄-in. (19-mm) sieve.

1.5.4 Method 2B—Using oven-dry material and an 11-in. (279.4-mm) diameter mold; applicable for materials with maximum particle size of 2-in. (50-mm) or less.

1.5.5 It is recommended that both the saturated and dry methods (Methods 1A and 2A, or 1B and 2B) be performed when beginning a new job or encountering a change in soil type, as one method or the other may result in a higher value for the maximum dry unit weight. While the dry method is often preferred for convenience and because results can be obtained more quickly, as a general rule, the saturated method should be used if it proves to produce a significantly higher value for maximum dry unit weight.

1.8.1 The gravitational system of inch-pound units is used. In this system, the pound (lbf) represents a unit of force (weight), while the unit for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculations are involved.

1.8.2 The slug unit of mass is almost never used in commercial practice; for example as related to density, balances, and the like. Therefore, the standard unit for mass in this standard is either kilogram (kg) or gram (g), or both. Also, the equivalent inch-pound unit (slug) is not given/presented in parentheses.

1.8.3 It is common practice in the engineering/construction profession, in the United States, to concurrently use pounds to represent both a unit of mass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolute system and the gravitational system. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/present the slug unit for mass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in lbm/ft³ shall not be regarded as nonconformance with this standard.

1.8.4 The terms density and unit weight are often used interchangeably. Density is mass per unit volume whereas unit weight is force per unit volume. In this standard, density is given only in SI units. After the density has been determined, the unit weight is calculated in inch-pound or SI units, or both.

1.9.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industry standard. In addition they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives, and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analytical methods for engineering design.