Which procedure best verifies overall compliance with compaction requirements in the field?

• A. Spot checks on critical areas
• B. Field density tests (nuclear gauge or sand cone)
• C. Visual inspection only
• D. Moisture content measurement alone

Answer: (B)

Direct measurement of in-situ density across the work area is what verifies compaction. Field density tests using a nuclear gauge or sand cone provide actual density (and moisture content) in the compacted material. With that data you can compute the dry density and compare it to the specified maximum dry density to determine the percent compaction, ensuring the entire section meets the requirement rather than just a few spots. Properly spaced density tests give a representative picture of overall compaction and are the reliable way to confirm compliance.

Spot checks on a few spots can miss localized areas that are under-compacted; visual inspection can’t quantify density, and moisture content alone doesn’t prove adequate density since the material can be moist yet poorly compacted.