Base

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The base layer is the main 'load bearing' layer of the path. It is also referred to as the 'sub base' layer. A base layer is made up of one or more layers of well graded granular stone comprising a wide size distribution from large stones down to fine particles (dust). The larger stones interlock to provide most of the strength. The smaller stones and 'fines' fill in the gaps between the larger stone to help 'bind' the base layer together into a strong solid mass once it is compacted. The base layer should evenly spread the weight of users from the surface layer above to the formation layer below. A well constructed base layer will prevent settlement, rutting or cracking.

base in location

Path base in location...

The deeper a path's base layer is, the stronger it will be. Specifying the base layer depth requires four factors to be considered:

  • Path users – the types, frequency and loads they will impose

  • Formation strength – the load bearing capacity of the ground on which the path is being laid

  • Maximum aggregate size – the depth of base layer needs to be at least twice the size of the largest stones used to allow the stone particles to interlock properly

  • For more information about - How deep should your path base be? - read here.
  • Composition of the aggregate – some rock types or recycled materials will require additional thickness or layers to provide the required strength

The path's base layer will also regulate any surface imperfections left in the formation layer. A smooth, even and well compacted base layer is essential for a high quality surface.

Find out more about path bases here.

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