Researchers determine the durability of Roman concrete

The Pantheon in Rome, with the world’s largest unreinforced concrete dome, dates back to A.D. 128 and is still intact, and some ancient Roman aqueducts still deliver water to Rome.

Researchers have spent decades trying to understand the secret of this ultradurable construction material, particularly in structures that endured harsh conditions.

Now, a team of investigators from MIT, Harvard University, and laboratories in Italy and Switzerland, has discovered ancient concrete-manufacturing strategies that incorporated several key self-healing functionalities. The findings are published in Science Advances, in a paper by MIT professor of civil and environmental engineering Admir Masic, former doctoral student Linda Seymour, and four others.

Researchers have previously assumed that ancient concrete’s durability was based on pozzolanic material such as volcanic ash. These ancient samples also contain millimetre-scale bright white mineral features, which are recognized as a ubiquitous component of Roman concretes. These white chunks - lime clasts - originate from lime, another component of Roman concrete mix.