I've been reading up about reinforced concrete, as it is one if not the cheapest way how to build (with some solid foundation). I found out that it actually has quite poor durability (50-100 years or something). The reason for this, if I understand correctly, are the steel rebars, which work inside the concrete because of corrosion and deteriorate the construction by cracking the structure. If I also understand correctly, the rebar is used to make the structures more flexible and easier to build and bigger structures simply cannot be build just by using concrete (since then it would probably be easy to get longer durability as Pantheon seems to do just fine).
It might be completely dumb question but why they don't use stainless steel instead? From what I've read the cost of stainless steel is only about 4-5x more expensive. I did some very rough calculations and considering the price of land, price of work, price of concrete, price of everything what you put in the building afterwards like other engineering materials, the cost of building demolition in its life cycle and so on it seems like financially very shortsighted decision.
Or is it the case that the stainless steel would not prolong the lifetime so rapidly? If so, why?
(stainless steel should not corrode and the thermal attributes of steel and concrete seem to be almost the same)