Firstly thanks to Mike Taylor for the suggestion of slate across the
cavity,and thanks to Michael Mcneil for replying to my question about
making a dry mix for screeding.

Yesterday, we made the mix, placed it, but I am now wondering if we
made it too dry!
It compacted in the hand when squeezed, but absolutely no excees
moisture was present.

I wet the slab four times during the day before laying, and PVA'd 5:1
as we screeded.

Even after covering the screed with polythene, the top surface just
became dust, so today I went over the screed with a mist sprayer and
trowelled the surface.
However, it is still suspiciously loose on top.

Should the mix have been wetter, or is it normal for the top to become
a bit loose as it cures?

Is it irredeemable? - am I going to end up needing to seal it or put a
self leveler on to hold it together. Or dig the whole lot out :-(

Thanks in advance

Bill M