zlacker

We only use reinforced concrete. The type of work where simple concrete is enough are very rare.

>>GoToRO+(OP)
It may start to lose it's strength after 50 years, as designed, if kept under designated conditions.

As for decay, IIUC, it loses pH gradually, from the time you mix it, and that pH is the most important protecting factor that stops the steel from rusting.

Obviously though, a lot of factors have a huge factor on lifetime, including composition, construction, environmental conditions ...

>>GoToRO+(OP)
Simple concrete is enough in almost all cases for what we do - if we use enough of it. Rebar allows dramatically reducing the amount we use in most cases, with this predictable trade off

It’s rarely physics, almost always economics.

>>lazide+zc
Plain concrete is simply not allowed by code for many applications. So even if you could theoretically justify the design, you couldn’t get the permit to build it.

Physics, economics, and bureaucratics is a good summary of structural engineering. The last one can’t be ignored.