What is the maximum loose-lift depth for a single smooth drum vibratory compactor?

What is the maximum loose-lift depth for a single smooth drum vibratory compactor?

• A. 4 in
• B. 6 in
• C. 9 in
• D. 12 in

Answer: (C)

The main idea is that the depth a single smooth-drum vibratory roller can effectively compact in one pass is limited by how far the vibration and weight reach into the soil. For a single smooth drum, that practical compactable layer per pass tops out at about 9 inches. If you place a thicker lift, like 12 inches, the energy doesn’t reach the bottom, so the bottom portion stays loose and you’d need additional passes with thinner lifts to achieve uniform density. Lifts of 4 or 6 inches can be compacted well in one pass, but they’re not the maximum you can go for this machine. So 9 inches is the highest thickness reliably compacted per pass with a single smooth drum.

The main idea is that the depth a single smooth-drum vibratory roller can effectively compact in one pass is limited by how far the vibration and weight reach into the soil. For a single smooth drum, that practical compactable layer per pass tops out at about 9 inches. If you place a thicker lift, like 12 inches, the energy doesn’t reach the bottom, so the bottom portion stays loose and you’d need additional passes with thinner lifts to achieve uniform density. Lifts of 4 or 6 inches can be compacted well in one pass, but they’re not the maximum you can go for this machine. So 9 inches is the highest thickness reliably compacted per pass with a single smooth drum.