Concrete from a demolished school building and carbon dioxide (CO2) from the air have been formed into new blocks strong enough to build a house.

The team of University of Tokyo researchers behind the new method believe it could help to significantly cut down the CO2 emissions associated with the construction sector. An estimated 11% of global emissions are associated with the materials and construction of new buildings.

To make the new blocks, demolished concrete from a school building was crushed into a fine powder, sieved and then carbonated over three months. Carbonation is usually a slow, natural process occuring when compounds in concrete react with CO2 in the air to form calcium carbonate. The researchers performed a sped-up version of this process to recreate the same kind of concrete you would find in older buildings.

Once the process was complete, the team pressurised the material into layers in a mould and heated it to form the new block. Instead of making buildings from new...