Roman concrete
Scientists want to know why ancient structures are still going strong
It’s been dubbed the most durable building material ever, and it was created thousands of years ago. Ancient Roman concrete was used to create iconic structures such as the Pantheon and the Colosseum, but it’s the piers and sea walls that scientists are most interested in.
Many of these marine marvels are still standing while modern concrete decays within decades.
Using a combination of high-powered X-rays, Raman spectroscopy and electron microscopy, scientists from the University of Utah have uncovered the chemistry. The Romans used a mix of volcanic ash, quicklime (calcium oxide), chunks of volcanic rock and seawater, which triggers a chemical reaction. This reaction produces crystals that continue to grow over time, which strengthen the concrete and prevent cracks from developing.
Meanwhile, modern Portland cement uses sand and gravel particles as they are intended to be chemically unreactive. This means that any reactions that occur can expand and crack the concrete. The process is also responsible for approximately five per cent of global carbon dioxide emissions.
It is hoped that by figuring out the Roman’s exact formula we could in future replace modern concrete with a stronger, more environmentally friendly material that will truly stand the test of time in the way the Roman’s concrete has.