Scientists studying the nanostructure of concrete said a change in the process used to create the widely-used material could significantly reduce carbon dioxide emissions worldwide.

Tests conducted by a team of engineers from the Massachusetts Institute of Technology discovered the secret to cement's strength lay not in its ingredients, but in how its smallest particles are arranged.

"If everything depends on the organizational structure of the nanoparticles that make up concrete, rather than on the material itself, we can conceivably replace it with a material that has concrete's other characteristics — strength, durability, mass availability and low cost — but does not release so much CO2 into the atmosphere during manufacture," said Franz-Josef Ulm, a professor of civil and environmental engineering at MIT.

Cement — the mixture of limestone, clay and water that forms a glue to bind minerals into concrete — naturally aligns into the ideal structure for strength and durability, the team found.

Examining cement particles just five nanometres — or five billionths of a metre — in diameter, Ulm and his team found they organized naturally into the most dense arrangement possible for spherical objects: a pyramid structure like a stack of oranges at the grocery store.

But while its structure has a built-in density, making cement requires heating a limestone and clay mixture to temperatures as high as 1,480 C, a process that creates much of the carbon dioxide emitted during the manufacturing process.

The production of cement accounts for at least five per cent of the world's total carbon dioxide emissions, which is seen as an important contributor to global warming.

The researchers said replicating the structure of cement could be possible without the heat-intensive process of heating the limestone and clay if an alternative material could be found.

Ulm said he is currently looking at magnesium as a potential replacement for the calcium in cement powder.

"Magnesium is an earth metal, like calcium, but it is a waste material that people must pay to dispose of," he said.

Total world production of cement was 1,652 million tonnes, according to Environment Canada data from 2001. Canada's 16 cement plants produced 13.6 million tonnes of cement, or less than one per cent of total world production, according to those same figures.