Hydrometer Analysis

A soil is considered susceptible to frost when it contains 3 percent or more by weight of particles smaller than 0.020 mm in diameter. To determine whether or not a soil contains an excessive amount of that size particle, you must perform a particle-size analysis of the materials passing the No. 200 (0.074-mm) sieve. Do this by hydrometer analysis. For a full discussion of the procedures, refer to NAVFAC MO-330 or to ASTM D 422.