Site investigation · Laboratory: soil classification
Double hydrometer dispersion ratio calculator
Percent dispersion from the fraction finer than 5 µm with and without dispersant and mechanical agitation.
Standard: ASTM D4221 · AS 1289.3.8.2 (related)
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Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Finer than 5 µm without dispersant | 14 | % |
| Finer than 5 µm with dispersant | 36 | % |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Percent dispersion | 38.89 | % |
| Indication | intermediate |
- ✗ Non-dispersive (< 30%)
Method, formulas and assumptions
- Percent dispersion = 100*14/36 = 38.889 %
- Indication = IF(38.889>50,"dispersive",IF(38.889>=30,"intermediate","non-dispersive")) = intermediate
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.