Which method is commonly used for testing soil compaction?

The Proctor test is the method commonly used for testing soil compaction because it provides a standardized procedure to determine the moisture-density relationship of soils. This test helps determine the optimum moisture content at which a given soil type achieves its maximum density when compacted. Compaction is critical in construction and civil engineering projects, especially for roadways and foundations, to ensure structural integrity and prevent future settlement.

When conducting the Proctor test, soil samples are compacted in a mold at specified moisture contents, and the resulting densities are measured. This information is vital for engineers, as it allows them to specify the compaction requirements necessary to achieve the desired stability and performance of earthwork or construction projects.

The other methods listed, such as core sampling, plate load testing, and the California bearing ratio test, are useful in their own contexts but serve different primary functions in soil analysis. Core sampling assesses the subsurface soil profile and strength, plate load testing evaluates the bearing capacity of the soil, and the California Bearing Ratio test gauges the strength of subgrade soils and base materials. While important in the field of geotechnical engineering, these tests do not specifically focus on compaction as the Proctor test does.