Archaeology & History

How has Roman concrete lasted 2,000 years ?

By T.K. Randall
July 4, 2017

Image: Roman Legionnaire
Credit: Rennett Stowe / CC BY 2.0 (adapted) Whatever the Romans put in to their concrete, it has certainly stood the test of time - as evidenced by the continued survival of some 2,000-year-old structures in contrast to many modern efforts which have disintegrated within mere decades by the continuous battering of the ocean waves.

There are even historic accounts of the strength of Roman concrete such as that of Pliny the Elder, who in 79AD described how the concrete structures of the time "became a single stone mass, impregnable to the waves, and every day stronger."

Now according to a new study by scientists in the US, the answer to this mystery lies in the way seawater mixes with the volcanic ash and lime within the concrete to form interlocking minerals.

These then provide a virtually impregnable cohesion to the structure that can last for millennia."We're looking at a system that's contrary to everything one would want in cement-based concrete," said study leader Prof Marie Jackson from the University of Utah.

"We're looking at a system that thrives in open chemical exchange with seawater."

It is hoped that the findings could one day help modern engineers develop new, more durable types of concrete that also take advantage of this same strengthening mechanism.

Locating a replacement for the volcanic ash used by the Romans however could prove a challenge.

Source: Telegraph

Tags: Roman, Concrete