How to glue wood to smooth exterior concrete?
I would always aim to &quot;Float&quot; the sleepers on top of the concrete floor.  since concrete is always porous and will retain water (ok, your floor sounds screeded) but even still.. it will have water.
So to Float the sleepers. When you fix them to the surface. use some washers to raise the sleepers -- (if you wanted, you could get some strong rubber and make rubber washers -- however, depending on the mass of the beams, i would say you would have more sound deadening effect by adding some good quality silicon / sikaflex rubber between the sleepers and the deck boards.