loose screed

[lowster]

I have recently (4 weeks ago) had the floor re-laid in my house and the finished screed in areas is loose. If I rub my hand on that particular area the sand just comes away. Is there anything I can treat the surface of the floor with to prevent this happening and get it ready for laying tiles on top?

 

[simeonosen]

If it's only dusty you can treat with a brush on dustproofer:

However you must ensure it's sound and strong enough to lay tiles onto. If it remains powdery expect your tiles to lift and crack.

If it's crumbly and friable remove the top of the surface with a scabbler or other mechanical preparation equipment and lay a min. 6mm bonded screed.