Is it OK to pave without mixing?
As long as you not planning to put anything heavy on it it will be OK. Dry pouring concrete can have dry pockets were water did not get to. Usually using dry pouring to make a drive way for car, garage is sufficient and possibly with some light bearing structures(open steel/wood Structures) .

I used dry pouring for putting in posts mostly but even for a simple brick wall I used wet pouring and a vibrated the concrete to get rid of air pockets.

But it also important to what underlying soil you have and what you want to do with the slab.

I have heard where people put barns on dry poured concrete and they still standing. So it all depends on your situation really and if you use any reinforced grids or not.

EDIT

From your comment


  The form was 2x4 s, so 3.5". The underlying ground was hard-packed
  clay. i did use a wire-mesh as reinforcement.


I would say you made a really strong piece of concrete slab. The only thing that would have made it stronger was doing a wet pour. It is also good you put a mesh in because clay (even packed) will move constantly and if any cracks happen, the mesh will keep your slab from falling apart. 

By home building standards on clay you for home building you need a minimum thickness of 6inches with 0.2inch mesh. So in your place I would not worry about your slab failing soon.