During a compaction test, what is measured to determine the compaction effectiveness?

In a compaction test, the final dry density of the soil is a critical measurement used to determine compaction effectiveness. This measurement reflects how densely the soil particles are packed together and is an essential indicator of soil stability and strength. The higher the dry density, the more effectively the soil has been compacted, which is crucial for structural integrity in construction projects.

This value is factored into calculations to assess whether the compaction meets project specifications and is often compared to a specified maximum dry density obtained from standard compaction tests. By knowing the final dry density, engineers can evaluate if the soil will provide the necessary load-bearing capacity for the intended construction.

While time of compaction, volume of soil used, and soil moisture content are also relevant factors in the process, they do not provide a direct measure of the compaction’s effectiveness as the final dry density does. Time of compaction can influence density, but it is not a definitive measure; the volume of soil used may be less relevant if moisture content or other conditions change; and soil moisture content must be controlled but doesn’t directly indicate overall compaction success. Thus, the final dry density is the key metric in indicating how effectively the soil has been compacted.