We could all use some protection
On Monday, we're having a presentation on Cathodic Protection of Concrete Structures:
For those who don't know, the big problem with concrete, especially near road surfaces in places where snow and ice is a problem, is the corrosion of the steel reinforcing bars (rebars) inside. Concrete is permiable, so dissolved chlorides come in and cause the steel to corrode. Concrete is also really strong in compression but really weak in tension. There are two main problems with this: 1) that rebar is there to give the concrete strength in tension, and if you remove some steel, then your concrete structure isn't as strong anymore, and 2) rust takes up more space than the original steel, so this results in tensile stresses within the concrete as the rust tries to expand, which will cause the outer cover of concrete to spall off. Very bad stuff.
Now there are a few ways to combat this. The main thing we do now that we didn't do in decades past is use much more concrete cover (thickness of concrete between the exposed surface and the rebar). This will greatly delay the ingress of chlorides. Other options are coating the rebar with epoxy so that the chlorides can't get to it or using stainless steel.