Site investigation · Laboratory: compaction & field density
Compaction curve (standard / modified) calculator
Moisture–density points to MDD and OMC with zero-air-voids and 80 % saturation lines, plus field density ratio.
Standard: AS 1289.5.1.1 / 5.2.1 · ZAV line
Open the live calculator → All site investigation calculators
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 |
|---|---|---|
| Compactive effort | Standard (596 kJ/m³) | |
| Mould mass | 4220 | g |
| Mould volume | 944 | cm³ |
| Gs | 2.68 | |
| Mould + wet soil (g), moisture (%) | 6010, 8.1 6110, 10.2 6170, 12.0 6150, 14.1 6090, 16.0 | |
| Field dry density (optional) | 1.78 | t/m³ |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Maximum dry density MDD | 1.845 | t/m³ |
| Optimum moisture content OMC | 11.8 | % |
| Saturation at optimum | 70 | % |
| Field density ratio (dry) | 96.5 | % |
| Point 1: w, ρd | 8.1 %, 1.754 | t/m³ |
| Point 2: w, ρd | 10.2 %, 1.817 | t/m³ |
| Point 3: w, ρd | 12.0 %, 1.844 | t/m³ |
| Point 4: w, ρd | 14.1 %, 1.792 | t/m³ |
| Point 5: w, ρd | 16.0 %, 1.708 | t/m³ |
- ✓ Peak bracketed (points both sides of OMC)
- ✓ Curve stays below ZAV line
- ✗ Field density ratio ≥ 98 % (typical spec; check yours)
Method, formulas and assumptions
- ρ = (m − mmould)/V; ρd = ρ/(1 + w)
- Parabola through the three highest points gives MDD and OMC
- ZAV: ρd = Gs·ρw / (1 + w·Gs/S) with S = 1 (and 0.8)
- Density ratio = field ρd / MDD × 100 (standard compaction)
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.