Which type of roller compacts soil from the bottom up?

The sheep foot roller is specifically designed to compact soil from the bottom up. Its distinctive design features multiple protruding "feet" or pads that penetrate the soil as the roller is moved over it. When these feet press down into the soil, they create vertical stresses that help to compact the soil layers effectively from the bottom. This method is particularly beneficial for cohesive soils, such as clay, where adequate density and stability are required at deeper layers.

In contrast, other types of rollers, such as steel-wheel rollers and smooth drum rollers, primarily apply weight and pressure to the surface of the soil, leading to surface compaction rather than deeper layer consolidation. Vibratory rollers use a combination of vibration and weight, which can enhance surface compaction but may not effectively achieve the same bottom-up compaction as the sheep foot roller.

Thus, the sheep foot roller is the ideal choice for achieving thorough compaction in a bottom-up manner, making it particularly effective in specialized applications where deep soil density is crucial.