An operator is compacting a 250 mm lift of engineered fill consisting of sandy loam with some silt content. The project specifications require both surface sealing and good compaction throughout the lift. Which compactor type would offer the best compromise?

Question: An operator is compacting a 250 mm lift of engineered fill consisting of sandy loam with some silt content. The project specifications require both surface sealing and good compaction throughout the lift. Which compactor type would offer the best compromise?

Answer options:

• Smooth drum vibratory compactor for the entire process ✅ Padfoot roller for initial passes, followed by a pneumatic tire roller for finishing
• Pneumatic tire roller for initial passes, followed by a smooth drum for finishing
• Only a static steel wheel roller is needed for this material

Correct answer: Padfoot roller for initial passes, followed by a pneumatic tire roller for finishing

Explanation: For mixed soils or those requiring internal kneading followed by surface sealing, a combination approach is often best. The padfoot starts compaction, and the pneumatic roller seals the surface and improves density.