What type of roller is best used for clay materials?

The sheepsfoot roller is particularly effective for compacting clay materials due to its unique design, which features a series of cylindrical, protruding feet on the roller drum. These feet penetrate into the clay when the roller moves forward, allowing for more effective compaction by exerting pressure directly into the material. The increased weight and the geometry of the sheepsfoot roller help to achieve a higher density in cohesive soils like clay, which can be challenging to compact evenly.

In contrast, while vibratory rollers may enhance compaction in granular soils due to their vibration frequency, they are less effective on cohesive soils because the vibrations can lead to the displacement of the clay material rather than compacting it. Pneumatic rollers can increase compaction as well, but they mainly work well on granular bases and are not ideal for cohesive materials. Flat plate rollers, although useful in specific contexts, do not provide the depth of penetration necessary for effectively compacting clay layers. Therefore, the sheepsfoot roller is the optimal choice for achieving the desired compaction in clay materials.