Aggregates are granular materials used in construction work. They include sand, gravel, crushed stone, recycled concrete, recycled asphalt, recycled brick and slags.
What are recycled aggregates?
Recycled aggregates come from reprocessing materials that have previously been used in construction. There are two methods of producing recycled aggregate:
- at the site of the source - the benefits of this include saving on transport costs and the environmental benefits of reducing lorry movements
- in a central plant
Examples of recycled aggregate include recycled concrete from construction and demolition waste material and railway ballast.
What are recondary aggregates?
Secondary aggregates are usually by-products of other industrial processes that have not previously been used in construction. Secondary aggregates can be further sub-divided into 'manufactured' and 'natural', depending on their source.
Examples of manufactured secondary aggregates are pulverised fuel ash and metallurgical slags. Natural secondary aggregates include china clay stent and slate aggregate.