Paving slab movement problem on clay soil

Patio flagstones (slabs), concrete flags, stone flags including yorkstone and imported flagstones.
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bak37uk
Posts: 1
Joined: Wed Sep 23, 2009 9:45 am
Location: United Kingdom

Post: # 41921Post bak37uk

Some years ago, I laid about thirty 600 x 600 x 50 mm slabs between my shed and greenhouse.
I used 4 or 5 inches of compacted brick rubble for the base and laid the slabs using a 6 + 1 mix of sharp sand and cement.
Over time, the slabs have moved, so that now the surface is very uneven.

I think there are at least three potential problems:-
1) The sub-soil is clay which expands when wet and shrinks and cracks when dry.
2) There are trees and a hedge nearby. The roots almost certainly go under the slabs. Not only does this cause the soil to shift as the roots grow but they also and suck out moisture out causing the clay to shrink in the summer months.
3) I believe in the past, a trench may have been dug to lay drains, so the sub-soil may be less stable.

I want to lift and re-lay the slabs.
How do I make sure the problem doesn't happen again?
Would reinforcing bars or mesh in the sand & cement base help?
I don't particularly want to lay a solid concrete foundation slab underneath the paving slabs unless I really have to.

Mattds
Posts: 6
Joined: Mon Jan 25, 2010 5:49 pm
Location: Tameside

Post: # 45538Post Mattds

Its prob a bit late now but did you put a haunch of mortar along the edges of your path? this will help to prevent any movement.
Dont follow my footsteps i walk into walls.

Tony McC
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Joined: Mon Jul 05, 2004 7:27 pm
Location: Warrington, People's Republic of South Lancashire
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Post: # 45551Post Tony McC

Matt,

I'm guessing that no-one answered the original post because it asks questions that are more than answered on the main website. There's a tendency amongst the Brew Cabin Irregulars (and I'm probably the worst offender!) to skip posts that are covered on the main site.

Somehow, I suspect we might not see the OP again.
Site Agent - Pavingexpert

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