Which sieve is used in Method A of a Standard/Modified Proctor?

In Method A of the Standard/Modified Proctor test, the No. 4 sieve is utilized to separate coarse particles from finer particles in a soil sample. This is an essential step in determining the moisture-density relationships of soils, which is crucial for understanding compaction characteristics. The No. 4 sieve has an opening size of 4.75 mm, and by using it, we can ensure that the material passing through is primarily fine enough to assess its behavior under compaction.

Choosing the appropriate sieve is important because it allows for a consistent and standard approach when conducting the test, ultimately impacting how compaction specifications are established for construction projects. The other sieves mentioned, such as No. 6, No. 8, and No. 10, have larger openings than No. 4 and would allow more coarse material to pass through, which would not provide an accurate representation of the soil's fine material behavior. Thus, the use of the No. 4 sieve is critical in achieving reliable test results in soil compaction assessments.