Secondary aggregate
Low Carbon Concrete Routemap, Setting the agenda for a path to net zero, draft for consultation published by the Institution of Civil Engineers in 2021, defines secondary aggregates as: ‘Aggregates that are usually by-products of other industrial processes that have not previously been used in construction.’
The National Planning Policy Framework (NPPF), published by the Ministry of Housing, Communities and Local Government in 2021, defined secondary aggregates as: ‘…aggregates from industrial wastes such as glass (cullet), incinerator bottom ash, coal derived fly ash, railway ballast, fine ceramic waste (pitcher), and scrap tyres; and industrial and minerals by-products, notably waste from china clay, coal and slate extraction and spent foundry sand. These can also include hydraulically bound materials.’
This definition was repeated in the revised NPPF in 2024.
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