Which material is heaviest to place on top of a pipe?

Which material is heaviest to place on top of a pipe?

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

Answer: (A)

Weight of backfill material directly over a pipe affects the load the pipe must carry. Wet clay is the heaviest among common backfill options because moisture increases its density and the cohesive clay holds water, forming a dense mass that transmits more vertical load to the pipe. Dry sand is lighter due to the absence of moisture, gravel is heavy but typically not as dense as saturated clay, and topsoil, while compact, generally weighs less than saturated clay. So, the heaviest material to place on top of a pipe is wet clay.

Weight of backfill material directly over a pipe affects the load the pipe must carry. Wet clay is the heaviest among common backfill options because moisture increases its density and the cohesive clay holds water, forming a dense mass that transmits more vertical load to the pipe. Dry sand is lighter due to the absence of moisture, gravel is heavy but typically not as dense as saturated clay, and topsoil, while compact, generally weighs less than saturated clay. So, the heaviest material to place on top of a pipe is wet clay.