The rusting and getting wet is cyclical in nature and part of what accelerates that is the formation of cracks in the first place. Part of the maintenance of concrete is to fill any cracks that you can find to prevent it from getting worse. The cracks typically start small, and they might form in places that are hard to get to as well as being too small to see, so if the concrete is self-healing it will prevent some of these small cracks from getting worse on their own which should reduce the effect of expanding water (ice) as well as expanding rust.
The reinforcement material (rebar) already has a very close thermal coefficient of expansion to concrete and this can be thought of as kind of a lucky coincidence.
The reinforcement material (rebar) already has a very close thermal coefficient of expansion to concrete and this can be thought of as kind of a lucky coincidence.