The use of recycled and secondary aggregates to achieve a circular economy within geotechnical engineering

The construction industry’s current dependence on primary aggregates is unsustainable as these are non-renewable resources and the consumption of these materials has a high environmental impact. The global annual production of primary aggre-gates is estimated to be 50 billion tonnes. In Europe, where 2 billion tonnes of primary aggregates are produced annually, approximately 90% of aggregates are utilised by the construction industry, whilst over 1Gt of waste are sent to landfill; in the UK, 44% of landfilled waste arises from the construction industry. The drive to adopt a circular economy necessitates changes in resource use (including non-renewable aggregates). Recycling wastes, such as aggregates, could help this situation; whilst this concept is not new, it does not appear to have been widely embraced in geotechnical engineering. The aim of this paper is to highlight the benefits of increasing the use of alternative aggregates as this would enable the reserves of primary aggregates to be better maintained and less material would be landfilled—a win-win situation and a contributing step to-wards developing a truly circular economy.