A large-area elemental map (Calcium: red, Silicon: blue, Aluminum: green) of a 2 cm fragment of ancient Roman concrete (right) collected from the archaeological site of Privernum, Italy (left). A calcium-rich lime clast (in red), which is responsible for the unique self-healing properties in this ancient material, is clearly visible in the lower region of the image. Image Cortesia de the researchers (MIT)
Roman aqueducts built more than 2,000 years ago are still in operation. The Pantheon in Rome remains the largest dome made of unreinforced concrete in the world, with a diameter of 43.3 meters. At the same time, it is not unusual to see structures less than a decade old collapsing. Understanding why Roman structures remain standing has been the subject of studies by many researchers around the world. Why, even in hostile environments such as coastlines or seismic zones, do these structures remain intact? Is there some miraculous material or method that has been lost in history? An international group of researchers led by the Massachusetts Institute of Technology (MIT) has shed light on these questions, discovering that these structures had a previously overlooked capacity for self-healing, and the potentially huge environmental impact it can have, to create more durable concrete structures in the future.