Single-drum vibratory rollers and soil compactors work to compact subsoils and material such as asphalt. The roller is a steel cylinder that oscillates and or vibrates to eliminate the gaps between the small materials in the soil, aggregate, or asphalt. Some rollers work on concrete.
The operating weight of the machine provides compaction as well as the roller attached to it. Additional ballast can be added, usually in the form of water or sand. Other ballast can be used to increase the amount of weight applied to the surface being compacted.
Compaction can also be applied through a vibratory and / or oscillating movement of the drum. Vibratory is an up and down motion; oscillation is a side to side motion.
The roller, or drum, can be smooth or have projections. These are called padfoot or sheepsfoot rollers and provide a more aggressive compaction punch.