The concrete that the ancient Romans created is so durable that it may hold lessons for those who want to reduce carbon emissions.
Paul Preuss, from the Lawrence Berkeley National Laboratory, explains.
“The chemical secrets of a concrete Roman breakwater that has spent the last 2,000 years submerged in the Mediterranean Sea have been uncovered by an international team of researchers led by Paulo Monteiro of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), a professor of civil and environmental engineering at the University of California, Berkeley.
“Analysis of samples provided by team member Marie Jackson pinpointed why the best Roman concrete was superior to most modern concrete in durability, why its manufacture was less environmentally damaging – and how these improvements could be adopted in the modern world.
“ ‘It’s not that modern concrete isn’t good – it’s so good we use 19 billion tons of it a year,’ says Monteiro. ‘The problem is that manufacturing Portland cement accounts for seven percent of the carbon dioxide that industry puts into the air.’ …
“The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated – incorporating water molecules into its structure – and reacted with the ash to cement the whole mixture together.”
Apparently the key ingredients are found all over the world, enough to make a big difference in construction — and carbon emissions.
There’s more at the Berkeley Lab site for readers who can follow a technical explanation.
Photo: Berkeley Lab
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