Roman concrete was durable and self-repairing, and quite a bit of it is still around, whereas modern concrete’s lifespan can be measured in decades. The assumption had been that this because of a key ingredient: pozzolanic ash. But a study published yesterday in Science Advances suggests that the Roman process hot mixed quicklime, leaving lime clasts in the matrix that, by dissolving when exposed to water and then re-forming, could fill cracks in the concrete. More at MIT News.
Jonathan Crowe blogs about maps at The Map Room and writes and reviews science fiction and fantasy; his work has been published by AE, The New York Review of Science Fiction, Strange Horizons and Tor.com. He lives in Shawville, Quebec.