The Wonders of Roman Concrete

Many folks have already mentioned this item at Discovery.com about the concrete used in Trajan’s Market … here’s the incipit:

Sandy ash produced by a volcano that erupted 456,000 years ago might have helped a huge ancient Roman complex survive intact for nearly 2,000 years despite three earthquakes, according to research presented last week in Rome.

X-ray analysis of a wall sample from the Trajan’s Market ruins in Rome showed that the mortars used by ancient Romans contained stratlingite, a mineral known to strengthen modern cements.

“It is the first time that stratlingite is recognized in ancient mortars,” Lucrezia Ungaro, the Trajan Forum archaeological chief, told Discovery News. “This is amazing, and shows the technical expertise of Roman builders.”

Including a semicircular set of halls arranged on three levels, the “Market” complex is traditionally attributed to Apollodorus of Damascus, a Syrian architect who worked primarily for the Emperor Trajan. A gifted and innovative designer, Apollodorus is credited with most of the Imperial buildings, including the Forum of Trajan and Trajan’s column.

Dating to 113 A.D., the enormous complex is no longer believed to be the world’s first shopping mall, but rather a sort of “multi-functional center” with administrative buildings for Trajan, who ruled from 98 to 117 A.D.

Amazingly, the huge complex survived three devastating earthquakes — in 443 A.D., 1349 and 1703.

“Although the presence of the high-quality stratlinglite cements does not ensure protection from concrete cracking and failure from earthquake ground shaking, it shows the very well bonded nature of the wall concrete,” Marie Jackson, of Northern Arizona University’s department of history, told Discovery News.

Jackson co-authored the research with Barry Scheetz, professor of materials, civil and nuclear engineering at Pennsylvania State University, and volcanologist Fabrizio Marra of Italy’s National Institute of Geophysics and Volcanology.

For those of you collecting such things, in the past we’ve noted items on Roman ‘hydraulic’ concrete and how Roman concrete was ‘greener’ than that which is generally in use today. We should also mention romanconcrete.com, which has a pile of articles on the subject.

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