I do have some ice melt outside, there is expansion joints there. We did lay the pipe and the concrete was poured over it 4". They came back a day later and cut the expansion joints in. But they are only an inch in. I don't run the ice melt all the time. Maybe two three times a year so the concrete is exposed to minus 20 deg's F.
I can't find a picture of that installation otherwise I would put it on.