Why should aggregates be recycled?
Recycling makes sense. Aggregates come from natural deposits on the Earth’s surface that can take millions of years to form – that’s why we call them non-renewable resources.
Recycling aggregates can help preserve land, reduce energy consumption, reduce waste and conserve natural resources.
If we recycle aggregates, can we stop extracting them all together?
No. Although we can reduce the demand for aggregates through reuse and recycling, we still need newly extracted aggregates for many uses and only a limited amount of used aggregate material is currently available for recycling.
Recycling is only one part of conserving aggregate resources. Reducing the use of aggregates can also help us conserve.
How much do we recycle now?
In 2007 about 13 million tonnes of the aggregate used in Ontario was estimated to come from recycled sources – or about seven per cent of the total used. Since this information is not always tracked, additional aggregate recycling may be taking place that we don’t know about.
More recycled aggregates are used in road construction than for any other use. The Ontario Ministry of Transportation has been using recycled aggregates from asphalt pavements since the mid-1970s to build Ontario’s highways. Concrete from buildings, sidewalks and overpasses is also recycled.
Are there limits to recycling?
While much of the material used to build roads can be successfully recycled into new roads, other used aggregate materials are not currently suitable for recycling. For example, mine waste rock is produced far from markets for aggregates, and some mine waste may release chemicals that are harmful to the environment.
We also don’t yet know how to recycle some materials as useable substitutes for aggregates, or do it at a reasonable cost.
Even when recycled materials have been shown to perform well, they may not be seen as suitable for construction purposes. Some contracts require only newly extracted aggregates for road building and other construction, even though recycled material could be used successfully. Overcoming these challenges can help increase the use of recycled aggregates.
