The UK is fortunate in having an abundant supply of primary aggregates that can be sourced from numerous sites throughout the country. However, there is growing pressure on producers and consumers to move towards a more sustainable resourcing of construction aggregates by reducing the consumption of primary aggregates through switching to recycled or secondary aggregates.

The following definitions for recycled and secondary aggregates are widely used:

Recycled Aggregates: derived from reprocessing materials previously used in construction. Examples include recycled concrete from construction and demolition waste material (C&DW) and railway ballast.

Secondary Aggregates: usually by-products of other industrial processes not previously 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 (PFA) and metallurgical slags. Natural secondary aggregates include china clay sand and slate aggregate. More information about recycled and secondary aggregates.

Approximately 275 million tonnes of aggregates are used each year in the UK as raw construction materials and of this supply, around 70 million tonnes are already derived from recycled or secondary sources1. The UK is a leading user of these materials in Europe and can be proud of the fact that 25% of UK aggregate demand is met with these more sustainable resources.

There is scope for this environmentally friendly option to be expanded further. Potential for obtaining additional supplies already exists in those construction, demolition and excavation wastes that are not currently being recycled and sent to landfill. There is also potential for better utilisation of secondary resources. Over the coming  years, these materials could increase the proportion of aggregate demand met with recycled and secondary aggregates to 30%2.

The suitability of using recycled and secondary aggregates for a wide range of applications has been well documented, including detailed project examples within the case studies tool.