The number of blows for compaction in the standard Proctor test is based on what?

The correct answer relates to the size of the mold used in the standard Proctor test, which directly influences the number of blows required for proper compaction. The standard Proctor test is designed to determine the optimum moisture content and maximum dry density of soil when compacted.

In this test, a specific volume mold is used, and the method prescribes a certain number of blows to be applied by a rammer of a defined weight from a specific height. This standardized approach ensures consistency in compaction efforts across different tests, facilitating reliable comparisons of soil behaviors. The size of the mold dictates how much soil is compacted and affects how the density is measured, hence demonstrating that the number of blows is pertinent to the geometry of the mold.

While other factors such as the type of soil or moisture content certainly play significant roles in the behavior of soils during compaction, they do not dictate the standardization of the number of blows. The standardization ensures that the test results can be replicated and compared regardless of the soil's characteristics.