AASHTO R 74-16 (2020) PDF Download

AASHTO R 74-16 (2020) is a standard practice that outlines the procedure for the wet preparation of disturbed soil samples for testing purposes. The standard primarily focuses on the mechanical analysis and determination of soil constants. There are two methods described in the standard: Method A and Method B.

Method A involves drying the field samples at a temperature not exceeding 60°C, conducting a wet separation using a 0.425-mm sieve, and then drying the separated soil at a temperature not exceeding 60°C. On the other hand, Method B specifies that the field samples should be kept at a moisture content equal to or greater than the natural moisture content. These samples are required to be shipped to the laboratory in sealed containers and should not be allowed to dry out before testing.

If no specific procedure is specified, Method A is considered to be the governing method. The standard also mentions that this practice was previously designated as test method T 146.