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More retro-technology examined:
Secret of how Roman concrete survived tidal battering for 2,000 years revealed
Sarah Knapton, Science Editor
3 July 2017 • 6:00pm
It is a mystery that continues to baffle modern engineers. Why do 2,000-year-old Roman piers survive to this day, yet modern concrete seawalls embedded with steel crumble within decades?
Even Pliny the Elder, writing in Naturalis Historia in 79AD, noted that concrete structures in ancient harbours, ‘become a single stone mass, impregnable to the waves, and every day stronger,’ despite being constantly battered by seawater.
Now scientists in the US think they have found the answer, and it could finally lead to modern sea defences which withstand time and tide.
They discovered that when saltwater mixes with the volcanic ash and lime used by Roman builders, it leads to the growth of interlocking minerals, which bring a virtually impenetrable cohesion to concrete.
"We're looking at a system that's contrary to everything one would want in cement-based concrete," said Prof Marie Jackson, a geology and geophysics research professor at the University of Utah who led the study.
"We're looking at a system that thrives in open chemical exchange with seawater."
Roman engineers made concrete by mixing volcanic ash with lime and seawater to make a mortar, and then added chunks of volcanic rock. The combination of ash, water, and lime produces what is called a pozzolanic reaction, named after the city of Pozzuoli in the Bay of Naples, triggering the formation of crystals in the gaps of the mixture as it sets.
etc...
http://www.telegraph.co.uk/science/...survived-tidal-battering-2000-years-revealed/
Secret of how Roman concrete survived tidal battering for 2,000 years revealed
Sarah Knapton, Science Editor
3 July 2017 • 6:00pm
It is a mystery that continues to baffle modern engineers. Why do 2,000-year-old Roman piers survive to this day, yet modern concrete seawalls embedded with steel crumble within decades?
Even Pliny the Elder, writing in Naturalis Historia in 79AD, noted that concrete structures in ancient harbours, ‘become a single stone mass, impregnable to the waves, and every day stronger,’ despite being constantly battered by seawater.
Now scientists in the US think they have found the answer, and it could finally lead to modern sea defences which withstand time and tide.
They discovered that when saltwater mixes with the volcanic ash and lime used by Roman builders, it leads to the growth of interlocking minerals, which bring a virtually impenetrable cohesion to concrete.
"We're looking at a system that's contrary to everything one would want in cement-based concrete," said Prof Marie Jackson, a geology and geophysics research professor at the University of Utah who led the study.
"We're looking at a system that thrives in open chemical exchange with seawater."
Roman engineers made concrete by mixing volcanic ash with lime and seawater to make a mortar, and then added chunks of volcanic rock. The combination of ash, water, and lime produces what is called a pozzolanic reaction, named after the city of Pozzuoli in the Bay of Naples, triggering the formation of crystals in the gaps of the mixture as it sets.
etc...
http://www.telegraph.co.uk/science/...survived-tidal-battering-2000-years-revealed/
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