Thermalite® Trenchblock® is a tried and tested, economical alternative to the construction of cavity walls with concrete infill, engineering bricks or heavy aggregate blocks for foundations. Also available as Hi-Strength Trenchblocks® where strengths of 7.3N/mm² or 8.7N/mm² (10.4N/mm² equivalent) is required.
- For use in soils of up to Design Sulfate Class DS 4
- Available with tongue and groove joints and handholds
- Improves thermal performance
Working dimensions Face dimensions (mm) 440 x 215, 440 x 140*
Thicknesses and weights Block thicknesses and weights at equilibrium density (for 440 x 215mm)
| Thickness (mm) |
255 |
275 |
300 |
355 |
| Trenchblock weight (kg) |
14.9 |
16.1 |
17.5 |
20.8 |
| Trenchblock 7.3N/mm² weight (kg) |
18.1 |
19.6 |
21.3 |
25.3 |
| Trenchblock 8.7N/mm² weight (kg) |
19.1 |
20.6 |
22.5 |
26.6 |
Block thicknesses and weights at equilibrium density (for 440 x 140mm)
| Thickness (mm) |
255 |
275 |
300 |
355 |
| Trenchblock weight (kg) |
9.7 |
10.5 |
11.4 |
13.5 |
| Trenchblock 7.3N/mm² weight (kg) |
11.8 |
12.7 |
13.9 |
16.4 |
| Trenchblock 8.7N/mm² weight (kg) |
12.5 |
13.4 |
14.7 |
17.3 |
Properties Mean compressive strength not less than 3.6N/mm² (7.3N/mm²: Hi-Strength)
Designed thermal conductivity below ground (λ) 0.23W/mK (0.31W/mK: Hi-Strength)
Specified gross dry density 600kg/m³ (730kg/m³: Hi-Strength)
*Not available with tongue and groove joints.