What is required for roadbed soils to be effective?

• A. They should be saturated
• B. They should be compacted to near maximum density
• C. They should be loose and well-drained
• D. They should have low compaction

Answer: (B)

For roadbed soils to be effective, compaction to near maximum density is crucial. Compacted soils provide the necessary support for the overlying pavement structures, helping to distribute loads from traffic evenly and minimizing the risk of deformation or settlement. When the soil is compacted effectively, the air voids are reduced, and the particles are closely packed together, which enhances its load-bearing capacity and stability.

In contrast, saturated soils can weaken the load-bearing capacity and promote issues like consolidation and instability due to water pressure in voids. Loose, well-drained soils may not provide the strength needed to support loads and can lead to shifts or settlement under weight. Low compaction results in increased void spaces, which may also allow for movement or failure under stress. Therefore, achieving near maximum density through proper compaction techniques is essential for effective roadbed performance.