ASTM D 7263 : 2021

1.1.1Method A (Water Displacement)—A specimen is coated in wax and then placed in water to measure the volume by determining the quantity of water displaced. The density and unit weight are then calculated based on the mass and volume measurements. Do not use this method if the specimen is susceptible to surface wax intrusion.

1.1.2Method B (Direct Measurement)—The dimensions and mass of a specimen are measured. The density and unit weight are then calculated using these direct measurements. Usually, the specimen has a cylindrical or cuboid shape. Intact and reconstituted/remolded specimens may be tested by this method in conjunction with strength, permeability/hydraulic conductivity (air/water) and compressibility determinations.

1.2.1The gravitational system of inch-pound units is used when dealing with inch-pound units. In the system, the pound (lbf) represents a unit of force (weight), while the units for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculations are involved.

1.2.2It is common practice in the engineering/construction profession to concurrently use pounds to represent both a unit of mass (lbm) and of force (lbf). This practice implicitly combines two separate systems of units; the absolute and the gravitational systems. 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 of mass. However, the use of balances and scales recording pounds of mass (lbm) or recording density in lbm/ft³ shall not be regarded as nonconformance with this standard.

1.2.3The 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 SI or inch-pound units, or both.

1.3.1The 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 analysis methods for engineering design.