Under kitchen sink there is a copper gas pipe coming up through a large hole in the concrete floor. Want to seal this up preferably in a rodent proof way. Don't want to use expanding foam as this can put pressure on pipe and also mice and rats can munch through this no bother. Any ideas?
Sand and cement mix would be fine. You could also wrap a bit of denso tape around the pipe if you wished to do so (for protection).
You need to protect the pipe first cement will react with the copper pipe and make it weak and cause leaks..