Joined: July 2004
||Posted: 30 May 2017,11:46
Capping layers, and sub-base layers acn have an overall depth of anything you like, but should be constructed as individual layers not exceeding 225mm in depth due to the compaction limitations of even the best equipment.
So, if you had 2.5m to make up, that might be done as, say, 12 courses at 200mm, then a final 100mm course to a fine tolerance.
In real life, as Sean said, with that sort of depth we'd be looking to incorporate a number of layers of geo-grid, probably every 600mm or so. Actually, at a 2.5m build-up, I'd want an engineer to sign-off any proposed design so it's not my arse on the line if there were to be any problems further down the line.
Built-up as layers, with geo-grids to limit internal movement and absorb tension, and then properly compacted with regular density checks to ensure compaction was achieved to a minimum standard, then there should be almost no settlement over the service life.
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