Dry sharp or wet motar again

Patio flagstones (slabs), concrete flags, stone flags including yorkstone and imported flagstones.
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TOLIVER
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Joined: Tue May 24, 2005 5:58 pm
Location: UK

Post: # 8328Post TOLIVER

Sorry to ask what appears to be similar to many other posts on the board. I have searched and looked through others before posting.

I am about to lay 32 square metres of concrete riven slabs in a path that is 36 inches wide.

I have three pallets of random sizes @ 600 X 450 450 X 450 and 450 X 300.

I have prepared a sub base using scalpings which is now rock solid (its had six months to compact since I started)

The question I have is what bedding material to use. The paving supplier suggested 4:1 motar , I think using building sand. Whist each slab is not that small, the path will be the same level as the grass garden each side of it.

It appears from the website that sharp sand at 10:1 would be more suitable.

The issue I am concerned about is what is an unsupported edge(which the website says should be on motar) Does grass constitute a supported edge as the paving does not rise higher than the grass. I am concerned about the slab moving / rocking

What I am asking is should I bed on motar or grit sand / cement mix and what ratio please ?

Tony McC
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Post: # 8392Post Tony McC

10:1 grit sand with cement. You can up that to 8:1 and dampen it down at the edges and bring it up the outside edge as a minimal haunch to prevent the flags sliding into the grass over the longer term.

4:1 is ridiculously over-strength, and the use of building sand for bedding is a total nonsense.
Site Agent - Pavingexpert

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