Materials and mixing methods used as sub-base to support trees.
| Materials | ||||||
|---|---|---|---|---|---|---|
| Stones (80–150 mm) | Stones/crushed stones (32–80 mm) (32–45 mm) | Leca-concrete blocks* (100 × 100 mm) | Crushed lava (32–45 mm) | Crushed bricks (25–50 mm) | Sand mix (0.2–0.5 mm) | |
| Installation methods | water mix dry mix | premix water mix | premix | premix water mix dry mix | premix water mix | premix |
| Growing medium | topsoil | topsoil | topsoil | topsoil | topsoil | humus/compost |
| Density of material (g/cm3) | 2.7 | 2.7 | 1.0 | 1.8 | 1.8 | 2.6 |
| Porosity of material (vol. – %) | 0 | 0 | approx. 15 | approx. 55 | approx. 30 | 0 |
| Voids in compacted material (vol. – %) | 45 | 45/40 | 56 | 38 | 35 | 45 |
↵* Leca is the Danish commercial name for Light Expanded Clay Aggretates.