Comparative life cycle assessment between imported and recovered fly ash for blended cement concrete in the UK

A UK government report released in 2017 indicated that fly ash (FA) production locally is expected to seize after 2021. This means that for the construction industry to meet its continuously increasing demand for an Ordinary Portland Cement (OPC) replacement, FA would probably need to be either imported or recovered from landfills through energy-intensive processes. Recent reports show that companies in the UK have already started importing FA from several countries from which Germany and China were chosen as case studies to exemplify the closest and furthest respectively. The environmental impact associated with the FA transportation raises concerns about the environmental sustainability of the final concrete product. Therefore, this study focuses on using a life cycle assessment (LCA) tool to analyse the environmental impact of importing FA from Germany and China and compare that to recovering landfilled FA in the UK. The study is the first of its kind to investigate the environmental impact of any of the alternatives. Using a Cradle-to-Gate approach and a mix of primary and secondary data, these alternatives were modelled and compared to conventional OPC and currently available locally sources of FA. Results show that the environmental burden from transporting FA from China to the UK will overcome the environmental benefits of it replacing OPC. It is then concluded that the most promising alternative for cleaner production of blended cement concrete is to recover the 50 million tonnes of landfilled FA from the UK using the Dry-processing technique explained in the study. The second best alternative is to import FA from a country within the Europe region to the UK.