New British recipe for concrete promises to save a million tonnes of carbon dioxide emissions each year – the equivalent of over 3,500 transatlantic flights – if the changes are adopted across all UK construction sites
The first change to the concrete mix in 40 years has been revealed in the UK after the British Standards Institution (BSI) approved a new mix, which promises to slash CO2 emissions.
Limestone powder can now be added to the material in one of the biggest changes to concrete production “since the 1980s”. For every 5% of limestone powder added, a 5% CO2 reduction can be delivered per tonne of concrete, according to MPA UK Concrete, the group representing the UK concrete industry.
One of the most significant changes to the traditional ‘recipe’ for making concrete since the 1980s, is set to be introduced in the UK, helping architects and engineers decarbonise the construction of buildings and infrastructure.
The new concrete BSI ‘recipe’ blends finely ground limestone from UK quarries with other materials such as fly ash, a by-product from power generation and ground granulated blast furnace slag (GGBS), a by-product from the steel industry.
UK Concrete and cement manufacturing accounts for 7.7m tonnes of carbon dioxide emissions, equating to 1.5 per cent of the UK’s total carbon emissions.
The majority of the carbon dioxide emissions is associated with the production of cement, and using these supplementary materials such as limestone powder helps to reduce the amount of traditional cement (CEM I) to create a lower carbon concrete.
With the new standards now available, the CEM I content in concrete can be replaced with up to 20 per cent of limestone powder, a product widely available in the UK.
“Making concrete is a bit like baking except that with concrete, ingredients are combined to alter properties such as strength, deliver environmental performance and change the aesthetics of the finished material,” says Elaine Toogood, director, architecture and sustainable design at the Concrete Centre, she was speaking to Building.co.uk.
“In a climate emergency, this new approved standard is important to helping architects and engineers significantly lower embodied manufacturing emissions today and in the future, while delivering structural strength in buildings and infrastructure.
“Providing a new generation of concretes are an important part of the UK concrete and cement industry’s roadmap to net zero alongside other technologies including the use of decarbonised transport, fuel switching and Carbon Capture, Usage or Storage (CCUS) technology.”
For many years, GGBS and fly ash have been repurposed as an ingredient for concrete, but less of it is being produced in the net zero transition, so the use of limestone fines is important for helping to provide a sustainable source of materials to continue to lower the embodied emissions of concrete.
The new specification changes are part of a rigorous research and testing process over two years with the results then independently assessed for inclusion into the standard by the BSI technical committee for concrete.
