Using a Roman Recipe to Make Greener Concrete

To make modern concrete, the mixture has to be heated to 2640 degrees F. Since we use so much concrete, this has a major environmental impact; concrete manufacture produces about 7 percent of global CO2 emissions.

Looking for improvement, some scientists decided to consult the experts in concrete technology: the ancient Romans. After all, some Roman concrete work is still strong and stable 2,000 years later, and they did not have modern kilns capable of such high temperatures. It turns out that Roman "sea concrete," the kind they used in harbor installations, meets modern requirements for strength, durability and so on but only has to be heated to 1650 degrees F. The key is the large-scale use of volcanic ash in the mixture. Since volcanic ash is readily available in much of the world, its use could lead to a substantial reduction in CO2 emissions. The only drawback is that the Roman concrete takes longer to dry than modern mixtures,which would be a problem for some uses but not others.

If you're curious about Roman concrete technology, you might consider checking romanconcrete.com.