Block paving/slabs on new sub grade - Wait for new sub grade to settle?

[Wildwoodmc]

Hello,

Firstly thank you for the wealth of expertise and information that is shared on the site and in this forum.

My initial issue is laying pavers/slabs around a pool area, the new pool has been dug into a hill and then levelled, therefore the mountain side sub grade is stable, however the opposite side is newly laid earth. My question is: can I lay a sub grade, sand bedding and block pavers/slabs knowing that the earth will settle and drop up to 10/15 or even 20 centimetres? Would it suffice to top up the sub base and relay the pavers/slabs in 6 months or year when the earth has fully settled?
Thank you all in advance!

[seanandruby]

You need to dig out any soft earth down to a stable sub soil. Cover with a capping layer, compact then start your formation.

[Wildwoodmc]

Thank you Sean. That would mean close to 2.5 metres to the stable sub grade. Can I lay a number of capping layers to close that 2.5 metre gap? I saw that a capping layer should not be higher than 225 mm.

[seanandruby]

Had no idea it was that deep. It should of been filled in layers compacting as you went. Then maybe a geo-grid, capping, membrane terran, or similar then sub base.

[Tony McC]

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.

[Wildwoodmc]

Tony thank you, really appreciate the advice. Looks like I need to remove it all and start again with the layering, I guess the contracter should have known this - he knew I was going to lay something around the pool!