Fencing for a garden?

[Pinkness]

I have a small concrete back 'garden' and was wanting to section part of it off for the dog to go out to when it needs the toilet so its poo is confined to one space away from people walking in and out. But does anyone know what could be used as there is no grass to hammer fencing into and i dont want to have to start digging up concrete to put a fence in. It doesnt need to be a tall fence as its only a small terrier dog