Which material is the heaviest type of earth to put on top of a pipe?

Which material is the heaviest type of earth to put on top of a pipe?

• A. Dry sand
• B. Wet clay
• C. Gravel
• D. Loam

Answer: (B)

Heaviness here comes from density, or unit weight, of the backfill material. When you place material around a pipe, you’re adding weight per volume, and moisture really boosts that weight. Wet clay retains water and packs tightly, so its moist unit weight is higher than the other options. Dry sand has little moisture, so it’s lighter; gravel can be dense but without the added water it doesn’t reach the same high density as wet clay; loam is a mixed soil and generally ends up less dense than saturated cohesive clay. So, wet clay tends to be the heaviest material to put on top of a pipe because its moisture content and cohesive, fine-grained nature allow it to achieve the greatest packed density.

Heaviness here comes from density, or unit weight, of the backfill material. When you place material around a pipe, you’re adding weight per volume, and moisture really boosts that weight. Wet clay retains water and packs tightly, so its moist unit weight is higher than the other options. Dry sand has little moisture, so it’s lighter; gravel can be dense but without the added water it doesn’t reach the same high density as wet clay; loam is a mixed soil and generally ends up less dense than saturated cohesive clay. So, wet clay tends to be the heaviest material to put on top of a pipe because its moisture content and cohesive, fine-grained nature allow it to achieve the greatest packed density.