Which statement describes the compacting mechanism used by Pneumatic Tired rollers?

• A. Compact using dead weight only
• B. Compact using vibration with dynamic force only
• C. Compact using dead weight with dynamic force but no vibration
• D. Compact using dead weight and dynamic force (Vibration)

Answer: (D)

Pneumatic tired rollers compact with a combination of static pressure and a vibratory, dynamic force. The tires’ dead weight presses the asphalt, helping close larger air voids and provide uniform contact. At the same time, vibration delivers a dynamic input that reorients aggregates and further reduces air voids, boosting density, especially near the surface and at joints. This dual action—dead weight plus vibration—makes compaction more effective than either mechanism alone.