A recent study conducted by the Mineral Products Association (MPA) with funding from Innovate UK has revealed that the incorporation of waste clay and brick into the cement manufacturing process can significantly reduce the embodied carbon of the final product. The research, which spanned two years, found that reclaimed clays and finely-ground brick powder can be used to lower associated emissions compared to traditional CEM I cement.
The study's findings indicate that by adopting calcined clays derived from these materials, the UK construction industry could divert up to 1.4 million tonnes of materials from waste streams. Given the abundance of clay in the UK, this presents a valuable alternative to industrial by-products like ground granulated blastfurnace slag (GGBS) and fly ash, which have been increasingly scarce due to decarbonization efforts in the power and steel industries.
While the use of calcined clays as a secondary cementitious material (SCM) has gained traction in other parts of the world, this study marks a significant milestone in the UK. The research explored two heating methods—traditional rotary kiln and flash heating—to prepare the clay for use as an SCM. Both methods were found to produce high-quality calcined clays, demonstrating no significant difference in their effectiveness.
The project garnered support from various industry players, including Heidelberg Materials UK, Tarmac, Imerys Minerals Ltd, Forterra, University College London, and the University of Dundee. Dr Diana Casey, MPA Executive Director for Energy and Climate Change, emphasized the dual benefits of using brick waste and reclaimed clays. Not only do they reduce carbon emissions and waste, but they also have the potential to create a new market within the construction industry, stimulating economic growth, job creation, and investment in the UK.
The development of low-carbon cements and concretes aligns with the MPA UK Concrete's 'Roadmap to Beyond Net Zero.' This roadmap outlines the industry's commitment to achieving net zero carbon emissions and builds upon its impressive 53% decarbonization since 1990.
The study's findings offer a promising avenue for reducing the carbon footprint of cement production while simultaneously addressing waste management challenges. By incorporating waste clay and brick into the manufacturing process, the construction industry can make a substantial contribution to a more sustainable future.
