Soil and Rock - Bulk Factors
Soil and rock expansion - or swell - after mining.
Soil or rock from the borrow expands when dropped on the lorry or the landfill - or stockpiled. One cubic from the borrow does not translate to one cubic dump.
Bulking or swell factors for some materials:
| Material | Density at the Borrow 103 (kg/m3) | Bulking (Swell) Factor (%) |
|---|---|---|
| Basalt | 2.4 - 3.1 | 75 - 80 |
| Clay | 1.8 - 2.6 | 20 - 40 |
| Dolomite | 2.8 | 50 - 60 |
| Earth | 20 - 30 | |
| Gneiss | 2.69 | 75 - 80 |
| Granite | 2.6 - 2.8 | 75 - 80 |
| Gravel, dry | 1.80 | 20 - 30 |
| Gravel, wet | 2.00 | 20 - 30 |
| Gravel, wet w/clay | 50 - 60 | |
| Limestone | 2.7 -2.8 | 75 - 80 |
| Loam | 15 - 25 | |
| Quartz | 2.65 | 75 - 80 |
| Rock | 40 - 80 | |
| Sand, dry | 1.60 | 20 - 30 |
| Sand, wet | 1.95 | 20 - 30 |
| Sandstone | 2.1 - 2.4 | 75 - 80 |
| Slate | 2.6 - 3.3 | 85 - 90 |
| Soil | 1.2 - 1.6 | 20 - 30 |
- 1 kg/m3 = 0.0624 lb/ft3
Example - Swell Factor
After excavation of 300 m3 clay with bulking factor 40% - the clay swells to
(300 m3) (100% + 40%) / 100% = 420 m3
in the dump.
