Roman techniques may be applied to new cements making them stronger

The process of production was also far more environmentally-friendly

The Pantheon, Trajan's Market and the Colosseum have stood the test of time for nearly 2,000 years.

But unlike these majestic Roman structures, today's cities are plagued by crumbling 1960s concrete tower blocks and decaying fly-overs.

Now scientists have found a 'secret' ingredient in Roman concrete that helped it endure the elements – and they believe modern engineers could follow the recipe.

Pictured are the markets of the Trajan complex, constructed about 100 CE. Drill core concrete samples from the lower supporting wall were analyzsd in this study

Using X ray beams at the Advanced Light Source (ALS), the team studied a reproduction of Roman volcanic ash-lime mortar.

In the concrete walls of Trajan's Markets, constructed around 110 CE, this mortar binds cobble-sized fragments of tuff and brick.

Scientists looked at the mineralogical changes that took place in the curing of the mortar over a period of 180 days and compared the results to 1,900 year old samples of the original.

The team discovered that the volcanic ash creates a crystal structure that prevents tiny cracks from spreading.

The study found that the volcanic ash creates a crystal structure that prevents tiny cracks from spreading

The Pantheon (pictured), Trajan's Markets and Colosseum have stood the test of time for 2,000 years

The study by the University of California, Berkeley also found that the use of strätlingite crystals in the material showed no corrosion, with their smooth surface suggesting stability.

INGREDIENTS IN ROMAN CONCRETE The mortars used to bind the concrete structures are a mixture of 85 per cent volcanic ash, fresh water and lime. The mortar is thermally treated at a much lower temperature than modern cement. Coarse chunks of volcanic tuff formed up to 45 per cent of the concrete. Advertisement

And Roman concrete was ahead in its green credentials too.

Most modern concretes are bound by limestone-based Portland cement, which requires heating a mix of limestone and clay to 1,450 degrees Celsius (2,642 degrees Fahrenheit).

The process releases enough carbon – given the 19 billion tons of Portland cement used annually – to account for about seven per cent of the total amount of carbon emitted into the atmosphere.

Roman architectural mortar, by contrast, is a mixture of about 85 per cent volcanic ash, fresh water, and lime, which is calcined at much lower temperature than Portland cement.

The mortars used to bind Roman concrete structures are a mixture of 85 per cent volcanic ash, fresh water and lime. Pictured is the Colosseum in Rome

Coarse chunks of volcanic tuff and brick compose about 45 to 55 per cent of the concrete, resulting in what the researchers claim are significant reductions in carbon emissions.

Now the researchers want to take the Roman techniques and apply it to modern cements.

'We could greatly reduce the carbon emissions associated with their production also improve their durability and mechanical resistance over time,' said study leader Marie Jackson.