Minimum density after compaction on stabilized subgrade.

Minimum density after compaction on stabilized subgrade.

• A. 98% of FM 1 T-180
• B. 99% of FM 1 T-180
• C. 95% of FM 1 T-180
• D. 97% of FM 1 T-180

Answer: (A)

Achieving a high relative density is essential for stabilized subgrades because it gives the soil the strength and stiffness needed to support pavement loads and resist deformation. The field density is expressed as a percent of the laboratory maximum dry density obtained from the FM 1-T 180 test. For stabilized subgrade, the common requirement is to reach at least 98% of that maximum dry density. In practice, you measure field density (often with a nuclear gauge), correct for moisture, compare to the lab MDD, and verify it’s at or above 98%. This threshold helps ensure the subgrade won’t creep or fail under traffic and environmental stresses. While some projects may specify slightly different targets, 98% is the standard reference for stabilized subgrade.

Achieving a high relative density is essential for stabilized subgrades because it gives the soil the strength and stiffness needed to support pavement loads and resist deformation. The field density is expressed as a percent of the laboratory maximum dry density obtained from the FM 1-T 180 test. For stabilized subgrade, the common requirement is to reach at least 98% of that maximum dry density. In practice, you measure field density (often with a nuclear gauge), correct for moisture, compare to the lab MDD, and verify it’s at or above 98%. This threshold helps ensure the subgrade won’t creep or fail under traffic and environmental stresses. While some projects may specify slightly different targets, 98% is the standard reference for stabilized subgrade.