Reinforced concrete does not have the lifetime that was originally supposed during the postwar period when such structures proliferated. The Wikipedia entry for the Morandi bridge in Genoa suggests that the concrete properties were not fully accounted for in the design and led to the earliest diffculties requiring maintenance works not long after the brige was first built.
Making the bridge stays out of reinforced concrete seems like a really risky design choice. It might appear elegant, to those enamoured with concrete, but it is questionable to use them on a busy road bridge that is going to remain in place for more than five decades. And it is also negligent of the authorities to allow such a structure to remain in place for so long without planning a replacement.
Reinforced concrete has a lifetime of between 50 and 100 years. It should conservatively be judged at the lower end of this estimate for such an application (and if it turns out to be a reinforced concrete stay that failed and led to the collapse, that would indeed be correct: it only just managed to reach fifty years).
Almost all modern buiding construction globally uses this material and it is all going to have to be demolished and replaced within that sort of timescale. It seems incredibly short-sighted to use it for construction. It might be cheap, but the smaller initial outlay hides a much greater cost down the line, because the buildings are not going to last.
It incurs a massive energy cost to produce, but we are going to have to stop using it regardless of whether the construction industry makes the choice or not. The global supply of sand suitable for use in concrete is diminishing and its price is steadily rising. The Middle East, which is undergoing a construction boom, has to import sand from Australia because its own sand is unsuitable. But manufacturers are scouring riverbeds and devastating ecosystems to try to make up for the shortage.
