Scientists may have found magic ingredient behind ancient Rome ’s self-healing concrete

The ancient Roman Empire still makes its presence felt throughout Europe. Bathhouses, aqueducts, and seawalls built more than 2000 years ago are still standing—thanks to a special type of concrete that has proved far more durable than its modern counterpart. Now, researchers say they have figured out why Roman concrete remains so resilient: Quicklime used in the mix may have given the material self-healing properties. The work could help engineers improve the performance of modern concrete, says Marie Jackson, a geologist who studies ancient Roman concrete at the University of Utah, but who was not involved with the research. The Romans were not the first to invent concrete, but they were the first to employ it on a mass scale. By 200 B.C.E., concrete was used in the majority of their construction projects. Roman concrete consisted of a mixture of a white powder known as slaked lime, small particles and rock fragments called tephra ejected by volcanic eruptions, and water. Modern concrete, in contrast, is typically made from Portland cement: a mixture of limestone, clay, sand, chalk, and other ingredients ground and burnt at scorching temperatures. It also starts to crumble in as little as 50 years. Scientists have previously tried to explain why Roman concrete is so long-lasting. In 2017, for example, researchers found that—at least for structures exposed to the ocean— seawater reacted with the ingredients of the concrete , crea...
Source: ScienceNOW - Category: Science Source Type: news