Temporary works & site · Piling works
Bored pile: concrete volume, cage and pour calculator
Concrete and reinforcement quantities for a bored pile: theoretical and overbreak volume, trucks, tremie pour time, cage mass (longitudinal bars, helix or ligatures, spacers) and checks on cover, clear bar spacing and minimum steel. Elevation and section drawn to scale.
Standard: AS 2159 Cl 6 (cover, cage) · AS 3600 · tremie placement practice
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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 |
|---|---|---|
| Pile diameter | 0.9 | m |
| Pile length | 20 | m |
| Overbreak allowance | 15 | % |
| Cage length | 12 | m |
| Longitudinal bars | 12 | |
| Bar diameter | 24 | mm |
| Helix bar diameter | 12 | mm |
| Helix pitch | 200 | mm |
| Cover to helix | 75 | mm |
| Truck load | 7 | m³ |
| Tremie pour rate | 25 | m³/h |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Theoretical volume | 12.72 | m³ |
| Volume incl. overbreak | 14.63 | m³ |
| Trucks | 3 | |
| Pour time (tremie) | 0.6 | h |
| Cage mass (incl. 8 % laps/spacers) | 684 | kg |
| Clear bar spacing | 160 | mm |
| Longitudinal steel ratio | 0.85 | % |
- ✓ Cover ≥ 75 mm (AS 2159 cast-in-place)
- ✓ Clear bar spacing ≥ 100 mm (concrete flow) — 160 mm
- ✓ Steel ratio ≥ 0.5 % — 0.85 %
- ✓ Pour ≤ 4 h (initial set) — 0.6 h
Method, formulas and assumptions
- Volume = πD²/4 × L × (1 + overbreak). Cage: longitudinal bars over the cage length plus a helix of pitch s on the bar circle; 8 % added for laps, spacers and stiffening rings.
- Keep clear spacing ≥ 100 mm (≥ 4 × aggregate) so tremie concrete flows through the cage; AS 2159 Table 6.4.2 gives cover for exposure.
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.