As per Is code 2720: 8 section 4.1.1, Sieve No.4 is used to check whether aggregation materials after they have been broken into individual particles. and only individual particles shall be retained on the sieve no. 4. So, sieve No. 4 is used to check whether the aggregation materials have been broken down properly or not.
Based on ASTM D698-00a, Sieve no. 4 used to determine the method of compaction test. This Standard provides three Method of testing namely Method A, Method B, and Method C.
Method A may be used if 20 % or less by mass of the material is retained on the No. 4 (4.75-mm) sieve.
Method B Shall be used if more than 20 % by mass of the material is retained on the No. 4 (4.75-mm) sieve and 20 % or less by mass of the material is retained on the 3⁄8-in. (9.5-mm) sieve.
Method C - Shall be used if more than 20 % by mass of the material is retained on the 3⁄8-in. (9.5-mm) sieve and less than 30 % by mass of the material is retained on the 3⁄4-in. (19.0-mm) sieve.