Proctor Compaction Test

The Proctor compaction test is a laboratory procedure that determines the optimum moisture content at which a given soil or fill material can be compacted to its maximum practical density, by compacting samples at varying moisture levels and plotting the results as a Proctor curve.

Standard Proctor and Modified Proctor are the two common versions, differing in compaction effort. Results are commonly referenced before slab, pavement, or footing subgrade work to confirm the fill will adequately support the load above it.