Construct soil in 6-12 inch compacted lifts and RAP in alternate layers with 6 inch maximum compacted lifts. What is the maximum soil lift thickness?

Construct soil in 6-12 inch compacted lifts and RAP in alternate layers with 6 inch maximum compacted lifts. What is the maximum soil lift thickness?

• A. 6 inches
• B. 12 inches
• C. 18 inches
• D. 24 inches

Answer: (B)

The main idea is how thick a soil layer can be compacted in one lift. In this specification, soil lifts are allowed to be compacted in a range from six to twelve inches. Therefore the maximum soil lift thickness is twelve inches. This limit is set so that the compaction equipment can reliably densify the material and achieve a uniform density with the layers beneath, avoiding poor compaction, moisture pockets, or density variations that thicker lifts could cause. Lifts thicker than twelve inches aren’t permitted, while six inches is allowed but isn’t the maximum. The 18-inch and 24-inch options exceed the specified maximum.

The main idea is how thick a soil layer can be compacted in one lift. In this specification, soil lifts are allowed to be compacted in a range from six to twelve inches. Therefore the maximum soil lift thickness is twelve inches. This limit is set so that the compaction equipment can reliably densify the material and achieve a uniform density with the layers beneath, avoiding poor compaction, moisture pockets, or density variations that thicker lifts could cause. Lifts thicker than twelve inches aren’t permitted, while six inches is allowed but isn’t the maximum. The 18-inch and 24-inch options exceed the specified maximum.