> There is nothing special about roman concrete compared to moderns concrete. Modern concrete is much better
Roman concrete is special because it is much more self-healing than modern concrete, and thus more durable.
However, that comes at the cost of being much less strong, set much slower and require rare ingredients. Roman concrete also doesn’t play nice with steel reinforcement.
I think you are incorrect. Compared to modern concrete, roman concrete was more poorly cured at the time of pouring. So when it began to weather and crack, un-cured concrete would mix with water and cure. Thus it was somewhat self healing.
Modern concrete is more uniform in mix, and thus it doesn't leave uncured portions.
We have modern architecture crumbling already less than 100 years after it has been built. I know engineering is about tradeoffs but we should also acknowledge that, as a society, we are so much used to put direct economic cost as the main and sometimes only metric.
You would be very unhappy if you had to live in a house as built 100 years ago. Back then electric lights were rare. even if you had them the wiring wasn't up to running modern life. my house is only 50 years old and it shows signs of the major remodel 30 years ago, and there are still a lot of things that a newer house would all do different that I sometimes miss.
I've lived in a 100 year old house and and in a brand new house, they both had issues. That also both had advantages too.
Oddly the older house had a better designed kitchen. Our lives change over time and our housing has to adjust to that too.
> What if we built things that are meant to last? Would the world be better for it?
You'd have a better bridge, at the expense of other things, like hospitals or roads. If people choose good-enough bridges, that shows there is something else they value more.
Certainly, "enough" is doing a lot of work and things get blurry, but I think "good enough" is meant to capture some of that. Over building is also a problem. It isn't strictly true that building longer lived things is cheaper over time either, it obviously depends on the specific things getting compared. And if you go 100 years rather than 25 years, you'll have fewer chances to adjust and optimize for changes to the context, new technology, changing goals, or more efficient (including cost saving) methods.
Obviously, there's a way to do both poorly too. We can make expensive things that don't last. I think a large chunk of gripes about things that don't last are really about (1) not getting the upside of the tradeoff, cheaper (in both senses) more flexible solutions, and (2) just getting bad quality period.
It might very well be that building and maintaining a bridge for 100 years costs three or four times as much as building and maintaining one that last 50 years. If demolition costs are not same as cost of bridge well in long run replacing the bridge ever 50 years is cheaper.
On whole it is entirely reasonable optimisation problem. What is the best lifespan of single bridge over desired total lifespan.
"Good enough" bridges still last 50+ years. We could design a bridge to last 200 years but we won't even know if the design we have today will even be needed in 200 years. Maybe by then we all use trains in underground tunnels.