We're in process of rebuilding a tile shower stall in our 30 year old
Florida block home. We ripped all the tile and board off the walls
and ledge, the sliding door is gone (some dumpster diver snagged that
before the trash men could), and we chiseled the tile off the floor.
After we pulled the tile off the floor, we noticed the base, although
hard, firm and intact, is very damp feeling. Wanting to start good we
put down some industrial absorber (like cat litter) and within a day
it was totally wet with moisture. :O/ ???

The shower is in a dropped section of the foundation, the tile base is
built up from that. We'd rather just tile on top of this as it has
the proper slope and drain and we really don't want to rip this all
out. As we read online about shower stalls it appears the base under
the tile is a wet sand/concrete mix and we're not sure if this needs
to be totally dry or could we put the sealer (or shower base) on top
of this and just build.

Does the base layer under the floor tile need to be completely dry?

Thanks in advance for your help and info.