Re-laying Paving Slabs

[ben3290485]

I've taken up 6 paving slabs as there was a gap opening up. 3 I have taken up with the concrete underneath (and taken off what I can) and 3 which I have managed to peel off the concrete as there was no way I was going to pull out from underneath. I want to re-use the paving slabs so it still matches.

Do you think I could put down thin layer of adhesive (or something) on the concrete already there for the three I have managed to peel up or is this just going to be too thick and so won't sit flat? Could I use adhesive which I have already got and used for inside? It says it can be used for outside.

For the other three just mix sand and concrete?

Any advice really appreciated. Photos attached.

 

[Tigercubrider]

I don't understand the "now way that I was going to pull out" comment?

I'd stick drill the concrete then whack it with the bolster.
Then I'd use new sand/cement to lay the slabs
If there's a big hole either pulverise your old concrete or (easier) buy a bag of something like MOT to fill the hole and tamp it down