Why cover the concrete paving? As long as your birds have the shaving on the inner part that they can re-treat to they will be fine.
If the shavings get wet and damp you should remove them a.s.a.p. as they could go moudly very quickly and this would be fatal for your birds. I use a plastic dish in the flight area of my avairy where my quails can enjoy a dust bath and scratch around in. It's great as I can keep it away from areas that it could get wet or damp. On the dry sunny days i put straw in my flight area as the quails love to bury themselveds in it
