FOUNDATIONS

The actual foundation required should preferably be determined by a local consultant who would take into consideration the bearing capacity of the material.

Foundations for light vehicles

In general it is only necessary to level the existing soil and apply approximately 20mm of sandy loam. 

Foundations for heavy vehicles

Areas intended for heavy traffic usually need deeper foundations. A typical example would be a 150mm deep sub-grade of ballast laid and packed over the sub-soil. On top of this, a layer of sandy loam approximately 20mm deep is required to ensure uniform load transfer to the sub-grade.

LAYING PROCEDURES

1. Prepare the foundation as described above. Use barge boards and a screed board to level off sand. The sand should contain some humus as required.
2. Slabs are laid in regular rows and levelled; no joining is required. In flat areas a slight gap 5 to 10mm may be allowed between adjacent slabs; using a suitable spacing board between rows.
3. Filling and Seeding
4. Use clean soil, level off approx. 30mm below the slab top. Add a mixture of sandy loam, grass seed and suitable lawn starter, keeping the final level to approx. 20mm below the slab top to allow successful germination. If filled too high, car tyres will crush the grass. It is always safer to keep the soil level low as you can easily top up later if required, but not vice versa.
5. Mowing an Maintenance
6. When using a small mower, cuts should be made diagonally across the slab. A mild fertiliser should be applied twice a year.

Installation on stream slopes

BG slabs laid on stream slopes effectively prevent erosion.

Mannings: n>0.026 providing high grid/water surface friction and thus reducing boundary velocity below erosion level.

45� slopes may be made secure and grass established. Every second or third unit should be stacked to provide initial stability. Units should be aligned with their long sides parallel with the stream flow.