Paving over manhole cover

[misterboumsong]

My paving over my manhole cover has worked its way loose and so I chiseled out all the existing mortar just seeing if there is anything I should do other than fill with fresh mortar and stick paving back down see.pic
I've bought a bag of 25kg ready mixed mortar do I need to do anything else

 

[Amber69]

So how do you get access to the manhole?

 

[Alastairreid]

Yes, prime the back of the slabs with sbr/cement slurry so they don't come loose again...moreso if they are porcelain.

Amber69 it's a recessed cover designed to be lifted out with the slabs in it.

 

[^woody^]

Is that mortar suitable for what looks like such a thin joint?

External grade floor tile adhesive may be better