The subject is complicated. For example see this paper[0]. The setting of concrete goes on for a long time and the Romans were probably not aware of how long t

The subject is complicated. For example see this paper[0]. The setting of concrete goes on for a long time and the Romans were probably not aware of how long their concrete(s) was/were going to last. There is a type of 'survivorship bias' going on here. But still, I guess, they knew something important. Adding reinforcement to concrete may well be a source of shortevity - or what ever the complement to longevity is. [0] https://www.sciencedirect.com/science/article/abs/pii/S0022509616305919 https://www.sciencedirect.com/science/article/abs/pii/S00225...