The Roman recipe – a mix of volcanic ash, lime (calcium oxide), seawater and lumps of volcanic rock – held together piers, breakwaters and harbours. Scientists say this is the result of seawater reacting with the volcanic material in the cement and creating new minerals that reinforced the concrete. Writing in the journal American Mineralogist, Jackson and colleagues describe how they analysed concrete cores from Roman piers, breakwaters and harbours. By contrast, modern concrete, based on Portland cement, is not supposed to change after it hardens – meaning any reactions with the material cause damage. Jackson has previously argued Roman concrete should be used to build the seawall for the Swansea lagoon.

Source: The Guardian July 04, 2017 04:52 UTC