Feasibility of Using a Gyratory Compactor to Determine Compaction Characteristics of Base Course Aggregates

To explore the effectiveness of using a gyratory compactor to provide an accurate prediction of optimum in-place soil densities.

The most commonly used laboratory method to determine the maximum dry density and optimum moisture content of soils used in civil structures is the Standard and Modified Proctor tests. The Proctor test has remained relatively unchanged for decades even though compaction methods in the field have changed dramatically. One shortcoming of the Proctor test is that it uses impact loads to compact the soils, which does not accurately reflect field compaction; soil density in the field comes from a combination of kneading, vibration, and increased normal pressures. Consequently, a more appropriate method of compacting soils in the laboratory is needed. As part of the Strategic Highway Research Program, a device called a gyratory compactor was created in the early 1990s to more accurately predict in-place asphalt densities. Gyratory compactors simultaneously use static compression and a shearing action to compact asphalt mixtures. Because gyratory compactors more accurately predict in-place asphalt densities, this project will look at using this method to obtain the maximum dry density and optimum moisture content of construction soils.