Paving slabs on an existing concrete base help

[allusernamesareinuse]

I have a very thick concrete patio which I want to freshen up by laying 450mm sq slabs over it. I don't want to try breaking up 8" thick concrete and with slabs on top I will still be 200mm below the DPC - so al should be well.

The question: what is the best mortar mix to bed the slabs down, I was thinking 1:4 sharp sand and cement - would that be OK? or would I need to use a concrete mix?

Also can some mathematics expert calculate quantities for me please The area is 2 x 5 metres and I suppose 20mm deep(?)

Thanks in advance

 

[i_am_fubar]

You could get away with just sharp sand, but a bit of cement to bind it would be useful.

DO NOT use 5 blobs of morter. pavers have a tendancy to break and plants can root easily under them.

http://www.pavingexpert.com/layflag1.htm

Assume you're concrete is you sub base and do as above.[/url]

 

[r896neo]

you could not get away with just sand, it will become a swamp as water cannot get through the concrete.

On a solid concrete base you need to use a mortar bed. Ditto what fubar said about the dabs though it's not worth the short cut.

Paving expert has some excellent calculators to help work out quantities[/b]

 

[i_am_fubar]

My bad on the sand bed. Though I didn't think that would be a problem if there was a gradient on it?

 

[r896neo]

If you point with mortar but lay on a sand bed the pointing will crack as the sand is flexible. If you tight butt and joint with dry sand as for block paving water will get through but not get away making the whole thing a swamp and very wet sand can be quite fluid.