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http://www.bloomberg.com/bw/articles/2013-06-14/ancient-roman-concrete-is-about-to-revolutionize-modern-architecture

ancient roman concrete lasts longer than portland cement.
scientists have finally rediscovered what the romans did to make such long lasting cement.

Many years ago remember reading about a Roman road that took some getting through. They were building a new motorway either across the Pennines or the North Yorkshire Moors, when they came across a section of an old Roman road running transverse to their direction requiring it's removal.

From what I remember it delayed the motorway construction by months. Apparently the Romans had laid down a bed of pitch-soaked timber followed by a layer of flint and a layer of iron ore. Continuing this sandwich layering until it was to their desired thickness. Then they set fire to it.

The iron ore being smelted with the carbon from the burning timbers, formed some steel variant. Which with the embedded flint was seemingly impervious to modern shifting techniques, requiring it to be hand cut with arc welding kit - inch by inch. This was a two thousand year old road that was still as strong as the day it was built. I understand embedding flint in metal is commonly used nowadays to build the walls of bank vaults.

If one were to hypothesize that the average woman has her first baby at twenty years old, then two thousand years is only one hundred generations. Nothing in evolutionary terms. So although not having access to our collective knowledges they were just as intelligent as we are. They wasn't stoopid, them Romans.

Strange that modern Italy is now a chaotic disorganised mess where nothings works properly. The outskirts of Florence are reminiscent of, if not worse than, those of some Soviet era cities.
The motorway interchanges around Genoa are like something a 12 year old might have made from an old Meccano set.

The journalistic myth that until now no-one knew what Roman concrete was made from, is a very old chestnut. As this link explains, it has been known that the main constituents of Roman cement were a particular type of volcanic ash plus lime, for a very long time.

https://en.wikipedia.org/wiki/Pozzolana

I was taught about the "Pozzolanic action" of these materials over 50 years ago at university, the word Pozzolanic deriving from the town Pozzuoli near Naples, Italy, where millennia of eruptions of Mount Vesuvius have created a thick stratum of ash and pumice. I remember that particularly, because Pozzuoli happens to be the birthplace of my long-time fancy, the actress Sophia Loren. (The brain and the libido work together, sometimes!)

No doubt yet another group of academics from various science and engineering faculties has been engaged in an investigative exercise to "re-invent the wheel" as it were, and occupy themselves in this largely unnecessary odyssey to provide themselves and legions of PhD students with something to do ...

Using modern equipment to carry out crush analyses of concrete cores, to determine the precise proportions and mineral content of numerous samples will simply add a few decimal points to what every man and his dog has known to a satisfactory degree of accuracy, for generations. Concrete back-analysis of this kind is fun to do (I've had it done), but really the breathless, almost reverent tone of the article is laughable. "2000 years old secret" indeed, utter nonsense!

Re: Moors road - I would have thought it more sensible to just build over the roman road rather than cut through it. It would seem they were replacing a better foundation with a worse one. Just do some resilience tests and adjust the top cover accordingly. Quicker, cheaper, preserves the original artifact.

603DX - we certainly got details of roman concrete on my engineering course in the early '80s. We were fortunate to have the man rumoured to be the world's 'Mr Concrete' as one of the staff. They made us mix our own for projects.

When Ascension Island airfield was being upgraded in 1984 the pervious crushed lava was replaced with concrete using locally produced lava based cement. It achieved a 28 day hardness rating in 7 days. Now I know the runway is breaking up but not sure when it was laid.