Why Roman concrete is outlasting modern concrete

[davidb]

https://www.theguardian.com/science/2017/jul/04/why-roman-concrete-still-stands-strong-while-modern-version-decays

[Nick Harbud]

Of course, it did not last quite so well in places like Caesarea Maritima and, whatever strength Roman concrete might have possessed, it pales into insignificance compared to steel reinforcement.

[Patrick Waterson]

Although its durability with or without steel reinforcement might be something to amaze later millennia ... one wonders whether there would be a place for steel-reinforced Roman concrete in modern construction.  (The likely answer is: yes, but merely as an excuse for today's architects to shave even more off safety margins.  If it is stronger, they will use less of it.)

[Tim]

Steel works slightly less well in salt water than the stuff the Romans used.

[Jim Webster]

Although its durability with or without steel reinforcement might be something to amaze later millennia ... one wonders whether there would be a place for steel-reinforced Roman concrete in modern construction.  (The likely answer is: yes, but merely as an excuse for today's architects to shave even more off safety margins.  If it is stronger, they will use less of it.)

fear not, modern engineers have a better command of the high ground. By shaving costs they allow society to spend more on nurses, firefighters or fidget spinners (insert correct good cause of choice)
Ancient engineers just wanted the damned thing to last so they didn't have to expend more slaves in the donkey work, because slaves aren't cheap

[Swampster]

Steel works slightly less well in salt water than the stuff the Romans used.

A proposal for another barrage in South Wales thinks the reinforcing steel will reduce the life span to around half of what is thought necessary to recoup the cost, due to the steel corroding. Without the steel, it wouldn't be strong enough in the first place, so the Roman concrete is being suggested. However, with limited supplies of the original material and the actual recipe being unknown at present, that is not going to happen soon.

On a related note, did anyone see the Alexander Armstrong programme where they mapped some of the mine workings under Rome? Seems like there are so many excavations that the city is built on an Aero. They were dug to get raw material for the concrete.

[Patrick Waterson]

On a related note, did anyone see the Alexander Armstrong programme where they mapped some of the mine workings under Rome? Seems like there are so many excavations that the city is built on an Aero. They were dug to get raw material for the concrete.

Hence the 'catacombs' of the early Christian era?

[Swampster]

Indeed, though the whole city is riddled with them. I think the Christian catacombs used tunnels outside the city limits, as was customary for burial.

[Nick Harbud]

The likely answer is: yes, but merely as an excuse for today's architects to shave even more off safety margins.  If it is stronger, they will use less of it.

An optimist says the glass is half-full.
A pessimist says the glass is half-empty.
An engineer says the glass is obviously twice as large as it needs to be.

[Patrick Waterson]

The likely answer is: yes, but merely as an excuse for today's architects to shave even more off safety margins.  If it is stronger, they will use less of it.

An optimist says the glass is half-full.
A pessimist says the glass is half-empty.
An engineer says the glass is obviously twice as large as it needs to be.

Elegantly put.  But the drinker might think otherwise ...