Which hammer weight is used for standard proctor testing?

• A. 10 pounds.
• B. 8 pounds.
• C. 4 pounds.
• D. 5.5 pounds.

Answer: (D)

Standard Proctor testing uses a specific energy input defined by a 5.5-pound hammer dropped from a height of 12 inches. This combination is chosen to compact soil in layers so you can determine the maximum dry density and the optimum moisture content for that soil. The energy level is lower than in the Modified Proctor, which uses a heavier hammer (10 pounds) and a higher drop (18 inches) to simulate more intense compaction. So the 5.5-pound hammer is the one that matches the standard procedure.