Three reasons to consider using recycled aggregates

Looking for a reason to build differently? We’ve got you covered.

#1: availability

Arguably the single biggest edge of recycled aggregate compared to virgin aggregate is its availability and proximity to virtually any market. Construction demolition is prevalent in all major urban centres, ensuring a supply of readily accessible material. If a structure is deconstructed and the resulting debris is used for suitable applications onsite, the owner reduces the need to purchase and transport virgin aggregate while also saving the hauling, dumping, and landfill costs for these materials.

In Canada, there were more than 3.3 million tonnes of CDW generated in 2002. (This comes from the 2005 Statistics Canada report, Human Activity and the Environment). In 2010, the United States generated 104 million tonnes, while Europe generated more than 500 tonnes in 2009–2010. (For more information, visit www.wastebusinessjournal.com/news/wbj20101005A.htm and www.biois.com/en/menu-en/expertise-en/assess/new-a/construction-waste-management-in-europe.html). (These numbers cover all materials falling under the CDW classification, including concrete.)

#2: reduce your footprint

The most obvious environmental benefit of specifying recycled aggregate is it proportionally reduces the amount of virgin aggregate that must be mined. This is no small consideration and it will likely become an even more significant factor going forward as social and environmental concerns rise over developing new quarries, while aggregate reserves are on the decline.

In addition to the benefits in terms of efficiency and economics, the close-to-market availability of recycled concrete aggregate also offers environmental and social advantages. Proximity to most project sites conceivably precludes transportation of thousands of truckloads of materials on local roads and highways. The implications of this traffic decrease include:

  • less congestion (and wear and tear) on roadways;
  • reduced traffic noise;
  • less dust related to the passage of trucks on gravel service roads from quarries; and
  • lower carbon dioxide (CO2) emissions related to transportation.

Again, the proof is in the numbers—an average ready-mix plant annually uses about 150,000 tonnes of aggregate, requiring delivery from nearly 4000 trucks every year.

#3: LEED potential

To demonstrate a commitment to sustainability, a growing number of private-sector owners and government organizations are aiming for Leadership in Energy and Environmental Design (LEED) certification of their construction projects.

LEED particularly rewards the reduction of waste at a product’s source. The use of RCA can help earn the following credits:

  • Materials and Resources (MR) Credit 2, Construction Waste Management;
  • MR Credit 4, Recycled Content; and
  • MR Credit 5, Regional Materials.

 

The LEED® Green Building Rating System recognizes recycled concrete in its point system. Credit 4 (Materials and Resources) states, “specify a minimum of 25 percent of building materials that contain in aggregate a minimum weighted average of 20 percent post-consumer recycled content material, OR, a minimum weighted average of 40 percent post-industrial recycled content material.” Using recycled aggregates instead of extracted aggregates would qualify as post-consumer. Because concrete is an assembly, its recycled content should be calculated as a percentage of recycled material on a mass basis.

Credit can also be obtained for Construction Waste Management. It is awarded based on diverting at least 50 percent by mass of construction, demolition, and land clearing waste from landfill disposal. Concrete is a relatively heavy construction material and is frequently recycled into aggregate for road bases or construction fill.

(with information from “Specifying recycled concrete aggregate – April 1, 2012” By Uwe Schutz, PhD, and R. Doug Hooton, PhD, P.Eng
https://www.constructioncanada.net/specifying-recycled-concrete-aggregate/)