Paving slab movement problem on clay soil

[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]

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.

[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.