Recycled Aggregates
The benefits and limitations, not a one-size-fits-all solution.
Though the words “green” and “sustainable” have been coined the catchphrases of the decade, recycling aggregates for infrastructure demand is nothing new. With growing technical innovations and rising standards, the process of recycling aggregate has become more efficient and practical; yielding positive impacts for the construction sector. At the same time, repairing our nations aging infrastructure has become a prevailing concern. This focus has made construction and demolition (C&D) debris recycling more important than ever.
Recycling concrete and asphalt helps supplement the raw materials necessary to create sustainable communities, but recycled aggregate alone cannot satisfy all construction aggregate needs. Currently, 80 % of asphalt removed from roads is reused, yet it is estimated that if all concrete and asphalt rubble were recycled, it would only provide 5% of the total demand for aggregates. So, what does this mean for C&D debris recycling? Simply that this green practice does have its limitations. By outlining the advantages and limitations of recycled materials, we are reminded that maintaining local sources of natural resources is important, while also continuing to support the use of recycled aggregate.
Advantages
Recycling aggregates helps divert waste away from landfills by annually crushing millions of tons of used concrete and asphalt pavement. By collecting and removing these materials to be crushed at a local recycling facility, long-haul transportation is reduced along with energy use. Additionally, wear and tear on roads and equipment that results from excessive transportation is eliminated.
Recycling aggregates helps strengthen local economies by providing aggregate needs for local projects; investing critical materials and revenue back into the community.
As long as transportation costs are kept low, the cost of recycled aggregate has a lower market price than virgin aggregates. Recyclers have the ability to charge a fee for accepting C&D debris. Where recycle sites are located close to the point of origin, or where disposal of materials into landfills would be too costly, recycled materials have an advantage. Thus, the added revenue allows for reduced prices; allowing competition with natural aggregates.
Creates a value-added product, new business opportunities and local jobs.
Limitations
In order to minimize the costs and maximize environmental benefits, recycled aggregate facilities must remain close to local markets. It is not economically or environmentally viable to meet the demands of construction projects that lie further away from the source.
Recycled aggregate is subject to specifications, meaning that in some cases, it must meet the same grading and quality specifications as virgin aggregate. This can sway contractors away from using recycled materials. In addition, CalTrans and local jurisdictions may only allow a certain percentage of recycled materials in a final product, further limiting the ability to use recycled aggregate.
Even if all C&D materials were recovered and processed, there would not be enough supply to keep up with the growing demands for aggregates.
The use of recycled aggregates is helping to define the construction aggregates business as a green industry that contributes to sustainability. Recycling practices continue to expand to meet infrastructure needs, reducing landfill disposal, and creating jobs. While recycled aggregate certainly plays a key role within the aggregates industry, these materials alone cannot solve California’s growing aggregate shortage.
Recycled Aggregate Legislation Update:
AB 812 (Ma) is the CalCIMA sponsored bill to encourage recycling of asphalt and concrete materials in the making of new asphalt and concrete. The bill will be heard in the Assembly Appropriations Committee January 9. If you plan to attend, please let crea@calcima.org know.
Recycled Aggregate Resources:
Calrecycle
USGS
CalCIMA
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