The secret to making sustainable, strong concrete may have been at the bottom the Mediterranean Sea for the past 2,000 years: Researchers believe that the ancient Romans created concrete that is more environmentally friendly and durable than modern cement….
Monteiro and his colleagues may have found an alternative: “sea” concrete used by Romans for harbor installations in the Mediterranean is made with a different concentration of materials than today’s mix of limestone and clay, which allowed it to be baked at a much lower temperature (about 1,650 degrees, compared to 2,640 degrees for modern “Portland” concrete). The result is a strong concrete that is less harmful to the environment.Engineers have had some success using the byproducts of coal power plants, known as “fly ash” to create a type of “green” concrete, but there is only so much fly ash to go around, Monteiro says. So engineers may soon do as the Romans did and use a mix of volcanic ash and limestone.
“Volcanic ash is available in a good deal of the world, usually there are entire mountains of it following a volcanic eruption,” he says. “The Romans were unbelievably good at using it as a building material.”