ASTM D1883-21 PDF Download

The ASTM D1883-21 standard is a test method for determining the California Bearing Ratio (CBR) of laboratory-compacted soils. The scope of the standard specifies that it is primarily intended for materials with a maximum particle size less than 3/4 in. (19 mm). However, if materials with a larger particle size need to be tested, the standard allows for modifying the gradation of the material to ensure it all passes through a 3/4-in. sieve while maintaining the same total gravel fraction.

The standard notes that CBR results for materials with a significant percentage of particles retained on the No. 4 (4.75 mm) sieve may be more variable than for finer materials, requiring additional trials to establish reliable results. The standard also provides for determining the CBR at optimum water content or a range of water contents, along with a specified dry unit weight.

Unless specified otherwise, all specimens are required to be soaked prior to penetration. The standard also discusses the use of different unit systems, with the inch-pound units using pounds as both a unit of mass and force. The standard emphasizes the importance of adhering to significant digits and rounding guidelines, as established in Practice D6026.