The Story:
How did the ancient Romans make such lasting buildings? They created far-flung networks of roads, aqueducts, and ports. Some of the remains of these structures are still with us after thousands of years although modern concrete structures require replacement after mere decades, as one learns in contemporary discussions of the need for more “infrastructure” spending. There is new light on the Roman methods.
Riddle Solved:
Recent research looked at bubbles of lime — inorganic material involving calcium, especially calcium carbonate — bubbles called “lime clasts” found in samples of Roman-era concrete. These lime clasts had long been thought to be contamination, evidence of poor quality control among those creating the mix.
The researchers wondered whether the lime might have been put into the mix as part of the recipe, not negligence. They hypothesized that the calcium carbonate was mixed in at very high temperatures. In time the team concluded that this hot mixing was actually the key to the durable nature of the resulting building material.
Strange New Worlds:
Efforts are now underway to commercialize the Roman recipe for concrete, bringing it into 21st century use. It rightly serves as a rebuke to presentist bias that our century can, after such a long period of condescension to supposedly negligent Roman mixers, belatedly adopt their methods for the improvement of our own infrastructure.
