Good point. The steel rusts, expands, more water gets in, more rust, concrete cracking, exposed rebar, rebar rusts away, no tensile strength, collapse.

(I was going to link to a picture, but at least half the images of corroded rebar found by search are AI-generated. Bogus technical pictures are getting out of control. Just saw some of the construction of the Panama Canal. No, steam shovels there did not have cowcatchers.)