For nearly two millennia, Roman concrete structures have stood the test of time, especially those poured during the imperial reign of Augustus Caesar (63 BC to AD 14).
Recently, a team of researchers from the University of California, Berkeley, civil and environmental engineering department, is working to understand what makes Roman concrete so resilient.
The team went to Cornell University to recreate the mix -- a simple recipe of volcanic ash and lime--specified by the architect Vitruvius (circa 15 BC to AD 80-70). They found it had remarkably different properties which gave it strength and longevity.
"The selection of the volcanic ash was a very good choice compared to other volcanoes around the area," said Dr. Marie Jackson, noting it was clearly by design.