The remains of vast networks of roads, aqueducts, ports, and massive buildings of ancient Romans have survived for two millennia. Many of these structures were built with concrete: Rome’s famed Pantheon, which has the world’s largest unreinforced concrete dome and was dedicated in 128 A.D., is still intact.
Researchers have spent decades trying to figure out the secret of this ultradurable ancient construction material, particularly in structures that endured especially harsh conditions, such as docks, sewers, and seawalls, or those constructed in seismically active locations.
Now, a team of investigators from MIT, Harvard University, and laboratories in Italy and Switzerland, has made progress in this field, discovering ancient concrete-manufacturing strategies that incorporated several key self-healing functionalities, says a release.
Besides pozzolanic material such as volcanic ash from the area of Pozzuoli, on the Bay of Naples, researchers found small, distinctive, millimeter-scale bright white mineral features — lime clasts — which have been long recognised as a ubiquitous component of Roman concretes. These tiny lime clasts gave the concrete a previously unrecognized self-healing capability.