LITHICRETE - Decarbonise the concrete industry by recycling battery-grade lithium waste

LITHICRETE aims to study the use of lithium mining waste as a resource to produce cementitious materials. This project will equip the UK with a net-zero strategy to cope with the upcoming lithium waste stream by directing it towards concrete manufacture. By 2030, the annual worldwide demand for battery-grade lithium is projected to exceed 2 million tonnes. The UK is committed to rely less on lithium-import and be a self-sufficient lithium economy by 2030, by identifying lithium geological deposits and investing in mining; companies in Southeast and Northeast of the UK, from Cornwall to Durham have already started exploring lithium reserves, with novel extraction and refinement processes under investigation. However, extraction and production of 1 tonne of lithium carbonate generates up to 10 tonnes of solid waste, known as lithium slag (LS). Such waste, mainly comprised of silicon and aluminium oxides, has the potential to be used as a cement replacement material in the production of concrete. In the UK alone, around 22 million tonnes of concrete were produced in 2021; an increase of 14% in comparison to previous years. Reducing the environmental impact of Portland cement has been deemed one of the major objectives in the fight against climate change, as stated in the recent UNEP report (September 2023). Replacing Portland cement with equally performing materials, such as supplementary cementitious materials (SCMs), is by far the most promising alternative to minimise the construction industry carbon emissions. Due to the global “switch” to renewable energies, and an increasing reuse of recycled over virgin steel, the availability of the most commonly used SCMs, fly ash (FA) and ground granulated blast-furnace slag (GGBS), is now limited and will soon be phased-out altogether. On the other hand, the availability of LS is projected to increase, due to the demand for production of electric vehicles, generating a favourable alternative SCM. LITHICRETE is timely, as it utilises an industrial by-product with increasing availability to meet future sustainable concrete demand. For LS to be adopted as a new material in construction, fundamental research questions remain unanswered on the physical microstructure of LS concrete, the chemistry of LS and what makes it suitable as an SCM. Therefore, investigation is needed to assess its performance, suitability and long-term resilience when used as a replacement for Portland cement. Through this funding proposal, LS as received from British Lithium Ltd plant (UK) will be characterised, its reactivity as an SCM will be explored and the optimum amount of LS as a cement replacement level in concrete will be established. LITHICRETE will establish lithium mining waste as the next generation cementitious material by investigating its incorporation into concrete in laboratory and real-scale environmental conditions. This will enable full assessment of the resilience and durability of LS concrete under different ageing and deterioration mechanisms. LITHICRETE will unite industrial partners, academics and policy makers in the field of design and assessment of sustainable construction materials and mineral extraction. The project will advance scientifically the design of next generation low-carbon concrete. LITHICRETE will establish a synergistic collaboration between the lithium industry and the construction sector to accelerate the UK net-zero agenda by achieving the production of zero-waste UK electric vehicles whilst drastically reducing the carbon footprint of our built environment.