Recycled concrete aggregate (RCA) is derived from construction and demolition residue, and is material that has previously been used in construction and in most instances has a known history of use.

It has similar properties to natural crushed rock aggregates and may be used in the same way. Provision for use of RCA in concrete is given in BS 8500-2.

Approximately 109 million tonnes of construction and demolition residues are created each year in the UK; around 60 million tonnes of this is concrete. This compares with the 165 million tonnes of natural aggregate used each year.

Subject to the energy required to crush, shred and separate construction and demolition residues, increased use of RCA as an aggregate in concrete will contribute towards policies of sustainable development by:

• reducing natural aggregate usage
• conserving landfill capacity
• potentially reducing transport impacts.