Researchers at Ecole Polytechnique Federal de Lausanne, Switzerland, have new funding to develop and test of a new blend of low-carbon cement. This new green cement has the potential to reduce the carbon footprint of construction sites by 40 per cent. Cement production comprises some 10 per cent of human CO2 emissions.

The challenge has been to make greener cement and reduce C02 emissions but maintain the strength and durability of the cement in the process. The most common construction cement is Portland cement. It also happens to be the cheapest to make and is the most caustic, containing toxic ingredients like silica and chromium. It has environmental concerns on every level from the high energy consumption related for mining it to the release of a high volume of greenhouse gases.

Ecole Polytechnique s green cement discovery was made mostly by accident. Their new cement was created from materials that were already available and widely used – calcined clay and ground limestone. But when those ingredients are added in large amounts to concrete mixtures, the aluminates from the clay interacted with the calcium carbonates from the limestone and created a cement paste that was less porous and stronger than traditional cement.

The researchers believe the discovery, called LC3 (Limestone Calcined Clay Cement), boils down to more calcified clay and limestone in cement mixtures, rather than less. They say LC3 has the potential to become a benchmark material for low-carbon concrete because clay and limestone are abundant materials found all over the world.