Laying 42mm pavers on a concrete base - How thin can the adhesive layer be

[etranger.mc]

I have to lay 42mm concrete pavers on to a new 40mm concrete base, put down 3 months ago. Can I use a mortar mix or could I use a tile cement to hold them? They are 600 x400 in size. Thinnest possible solution. Any ideas would be appreciated.

[lutonlagerlout]

40mm concrete base??
what is that base on?
40 mm of concrete is not much kop for anything mate
100mm should be minimum
LLL

[etranger.mc]

Yes it's on another concrete base which I have no idea how thick that is! lets just say very!
All I know is that the base is good but I'm stuck for height when it comes to laying the slabs on top.
If I put a a bedding layer of sand on what is the minimum I could use?