screed floor sandy and dusty now a hole !!

[Donnapaddy]

hi screened floor has now been down for about 7 weeks ,today I moved a table and there's a small hole which when I put my finger in yellow sand comes out ,in another spot there's not as much yellow sand but a small hole ..yesterday I had to chisel some of the floor away where it met our exsisting floor as it was too high and some was solid but some underneath was dusty and crumbly .the actual floor feels gritty to walk on is this normal or should it feel smooth ,I'm hoping the bloke didn't mix it wrong . Also on breeze blocks is it ok for the cement to be a bit powdery crumbly when you run a nail over it ..thanks

Manly