How the Soil Compaction Calculator Works
The Soil Compaction Calculator calculates the field dry density and compares it with the maximum dry density from a laboratory compaction test. This comparison is called relative compaction.
This is different from simply dividing wet density by dry density. In construction, compaction is usually checked by comparing field dry density against a specified maximum dry density.
Soil Compaction Formula
First, calculate dry density from wet density and moisture content:
Then calculate relative compaction:
Example Calculation
Field wet density = 2050 kg/m³ Moisture content = 12% Maximum dry density = 1900 kg/m³ Target compaction = 95%
Field dry density:
Relative compaction:
Since 96.33% is greater than the 95% target, this example passes the target compaction requirement.
Typical Target Compaction Values
| Application | Typical target |
|---|---|
| General fill | 90% to 95% |
| Road subgrade | 95% or higher |
| Structural fill | 95% to 98% |
| Project-specific geotechnical work | Use specifications |
Frequently Asked Questions
Is wet density the same as dry density?
No. Wet density includes water. Dry density removes the water effect and is more useful for checking compaction.
What is maximum dry density?
Maximum dry density is usually obtained from a laboratory compaction test such as a Proctor test.
What does 95% compaction mean?
It means the field dry density is 95% of the maximum dry density determined by the selected laboratory test method.
Can this replace field testing?
No. It only performs the calculation. Actual compaction verification requires proper field and laboratory testing.