Which equipment is specified for compacting the surface when the excavated area is left with A-2-7 Soil Groups?

Which equipment is specified for compacting the surface when the excavated area is left with A-2-7 Soil Groups?

• A. Smooth wheel roller
• B. Vibratory plate compactor
• C. Pneumatic roller
• D. Sheepsfoot roller

Answer: (D)

The choice of compaction method depends on how the soil behaves. A-2-7 soils are cohesive and respond best to kneading action rather than just static rolling. A sheepsfoot roller has feet that press and knead the soil as it moves, breaking up soil structure, reducing air voids, and densifying clayey surfaces more effectively than other rollers. This kneading action is key for cohesive soils, giving a more uniform, stable surface after excavation. In contrast, a smooth wheel roller works well on granular soils but tends to seal or ride over clay, a vibratory plate compactor relies on vibration that’s less effective for cohesive soils and can cause pumping, and a pneumatic roller is suited more to asphalt and granular bases. So for an excavated area left with A-2-7 soil, the heaviest-titted, footed roller—the sheepsfoot roller—is the best choice.

The choice of compaction method depends on how the soil behaves. A-2-7 soils are cohesive and respond best to kneading action rather than just static rolling. A sheepsfoot roller has feet that press and knead the soil as it moves, breaking up soil structure, reducing air voids, and densifying clayey surfaces more effectively than other rollers. This kneading action is key for cohesive soils, giving a more uniform, stable surface after excavation.

In contrast, a smooth wheel roller works well on granular soils but tends to seal or ride over clay, a vibratory plate compactor relies on vibration that’s less effective for cohesive soils and can cause pumping, and a pneumatic roller is suited more to asphalt and granular bases. So for an excavated area left with A-2-7 soil, the heaviest-titted, footed roller—the sheepsfoot roller—is the best choice.