Mystery of 2,000-year-old Roman concrete solved - Roman concrete contained aluminium tobermorite, a rare mineral that adds extra strength. When the Roman concrete was exposed to seawater, the tobermorite crystallised and spread.

Mystery of 2,000-year-old Roman concrete solved by scientists

http://www.msn.com/en-gb/news/world/mystery-of-2000-year-old-roman-concrete-solved-by-scientists/ar-BBDLPqT?li=AAmiR2Z&ocid=spartandhp

 

... Some 2,000 years after they were first erected, Ancient Roman harbours made from concrete are still standing across Europe. ...

... Concrete used for ancient sea walls was made by mixing lime, seawater, volcanic ash and rock. The combination produces a 'possolanic reaction' – named after the commune of Pozzuoli in Naples.

Researchers have now discovered that elements in the ash react with sea water, which actually strengthens the material. ...

... Romans created a rock-like concrete that thrives in open chemical exchange with seawater,"...

...

Researchers discovered the Roman concrete contained aluminium tobermorite, a rare mineral that adds extra strength. When the Roman concrete was exposed to seawater, the tobermorite crystallised and spread.

The researchers said that long-term exposure to sea water helped these crystals to continue growing, reinforcing the concrete and preventing cracks from developing. ...

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Egilsstaðir, 05.07.2017  Jónas Gunnlaugsson