Minimum density after compaction expressed as percent of FM 1 T-180?

Minimum density after compaction expressed as percent of FM 1 T-180?

• A. 97%
• B. 98%
• C. 95%
• D. 100%

Answer: (B)

The main idea is relative compaction: field density is compared to the maximum dry density obtained from the FM 1-T 180 lab test, and the result is expressed as a percentage. This tells you how dense the compacted soil is relative to its lab-determined capacity. For this item, the required minimum is 98% of the FM 1-T 180 maximum dry density. That means the in-situ density must be at least 0.98 times the lab maximum to meet specs. Using a field test (like a nuclear gauge) you measure the field dry density and compare it to the FM 1-T 180 maximum; if it’s at least 98%, the compaction requirement is satisfied. The other numbers would imply looser or unrealistic targets for this particular specification. In short, 98% is the threshold chosen to ensure sufficient bearing capacity and reduced settlement.

The main idea is relative compaction: field density is compared to the maximum dry density obtained from the FM 1-T 180 lab test, and the result is expressed as a percentage. This tells you how dense the compacted soil is relative to its lab-determined capacity.

For this item, the required minimum is 98% of the FM 1-T 180 maximum dry density. That means the in-situ density must be at least 0.98 times the lab maximum to meet specs. Using a field test (like a nuclear gauge) you measure the field dry density and compare it to the FM 1-T 180 maximum; if it’s at least 98%, the compaction requirement is satisfied.

The other numbers would imply looser or unrealistic targets for this particular specification. In short, 98% is the threshold chosen to ensure sufficient bearing capacity and reduced settlement.