Old Roof Tiles As Aquarium Decor

Some people down the road are having a new roof put on and there's a skip loaded with old tiles outside. I was wondering if I could use some in my tank to make a hiding place for the clown loach that would be big enough to fit them all?

Also if yes, what should I do to clean it up other than just washing them, I'd rather not lose the weathered look and if I scrub them too much they'll go terracotta colour.