Two tests: Standard Proctor (ASTM D698) uses a 5.5-lb hammer dropping 12 inches; Modified Proctor (ASTM D1557) uses a 10-lb hammer dropping 18 inches. Modified Proctor yields a higher density. Specs typically call for Modified Proctor on structural fill below buildings and roads.
Field compaction is verified with a nuclear density gauge or sand cone test. Each lift of structural fill (typically 8-12 inches of placed loose soil) is rolled and tested. Failure to meet density requires re-rolling and re-testing.
The compacted volume of the soil at 95-100% Proctor is denser than the bank state — that's the shrink factor estimators apply when computing the bank volume of soil needed to produce a given compacted fill volume.