Gyratory compaction evaluations include monitoring pressure, speed, angle of gyration, and height measurement during compaction.

• A. True
• B. The height measurement is not used
• C. Height measurement is also monitored during compaction
• D. Only pressure and speed are monitored

Answer: (C)

When evaluating gyratory compaction, you monitor several aspects of the process to understand how the sample densifies under the gyratory action. Pressure provides the axial load, speed controls how fast the rotator moves, and the angle of gyration sets the magnitude of the sample’s oval motion. Height measurement is included because it tracks how much the specimen shortens as compaction progresses. That height data is essential for assessing volume change and, together with the mold geometry and sample mass, allows calculation of bulk density and air voids—key indicators of compaction quality and consistency. So the height measurement is also monitored during compaction. Without it, you’d miss a critical piece of the density/voids picture, and focusing only on pressure and speed would ignore how the angle of gyration and the height change influence compaction behavior.