A German construction project has saved an estimated 136 tonnes of carbon dioxide from entering the atmosphere by using incorporating air pockets made of recycled plastic within its concrete slabs.

The two SparkassenVersicherung (SV) buildings in Mannheim’s Glückstein district are being built with concrete slabs developed by Cobiax, which include voids so that less concrete is used.The slabs have up to 35 per cent less material than solid reinforced concrete, thanks to the presence of the hollow spheres of plastic.

These spherical void formers fill parts of the slab not required for load bearing.Not only does this bring a reduction in concrete – one of the world’s main sources of carbon emissions – but also the lighter slabs reduce the energy expenditure required for transport.

For the 13-storey SV buildings, designed by architecture studio Sacker, this has meant using 1,613 tonnes less concrete across the two buildings, with significant CO2 savings to match.”The lower volume of concrete reduces pollutant emissions, so that we were able to achieve CO2 savings of 136 tonnes by using our system in the Quartier4 project,” said Cobiax.