Monday, June 24, 2013

Long lost Roman concrete formula rediscovered

Concrete has been used in the modern era for only 300 years or so.  It is based on "Portland" cement, so called because it can be cast into smooth forms reminiscent of fine limestone quarried in Portland Head, England.

The problem is that modern cement begins to crumble after 30 years, and won't generally last much longer than 50-70 years.  It's a big reason why we continually rebuild bridges.  The Romans built all sorts of structures that are still standing after 2000 years.  Why?

Their concrete didn't fall apart like ours does, because they didn't use Portland cement.  They used volcanic rock:
The researchers now know why ancient Roman concrete is so superior. They extracted from the floor of Italy’s Pozzuoili Bay, in the northern tip of the Bay of Naples, a sample of concrete breakwater that dates back to 37 B.C. and analyzed its mineral components at research labs in Europe and the U.S., including at Berkeley Lab’s Advanced Light Source. The analysis, the scientists believe, reveals the lost recipe of Roman concrete, and it also points to how much more stable and less environmentally damaging it is than today’s blend.

That’s why the findings, which were published earlier this month in the Journal of the American Ceramic Society and American Mineralogist, are considered so important for today’s industrial engineers and the future of the world’s cities and ports. “The building industry has been searching for a way to make more durable concretes,” Jackson points out.

...

The secret to Roman concrete lies in its unique mineral formulation and production technique. As the researchers explain in a press release outlining their findings, “The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated—incorporating water molecules into its structure—and reacted with the ash to cement the whole mixture together.”
This isn't just dusty history, this is something that can make a big difference to modern construction.  Not often you can get that from an archaeology dig.

7 comments:

Dave H said...

Cue the "ancient aliens" crowd in 3... 2... 1...

Randallsix13 said...

Forget aliens ancient or modern. How long until Mike Holmes starts using this on his show?

Anonymous said...

Are there any semi-recent formulations of cement and concrete that have aged better than others? I'm thinking of the 70-year-old concrete structures on Omaha beach that withstood a fair number of large diameter high velocity projectiles as well as constant salt laden moisture and appear to still be relatively stable and solid.

selsey.steve said...

If salt water is put with Portland cement then the resultant mix is entirely useless. Salt water absorption by already-set Portland cement is equally destructive, as 'rotting' concrete bridges over British motorways have shown. The roads are salted in winter to de-ice roads. Any Portland cement in contact with the resultant salt water suffers accordingly.
http://www.highways.gov.uk/roads/road-projects/M27-Junction-9-Pier-Replacement affects me directly.

Ratus said...

Am I the only one who read this as "Romulan" concrete?

NotClauswitz said...

That water-curing concrete stuff is still remarkable today, two thousand odd years later. Amazing stuff, why didn't we ever think of it? We're not so smart after all.

Anonymous said...

Coming soon - Vulcan Brand Cement. Guaranteed to outlive the civilization it's built for!