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Benefits  > Recyclable
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green design recyclable concreteConstruction and demolition waste in the U.S. is approximately 135 million tons annually, or about 3 lbs/person/day. Recyclable materials can be recycled at the end of their useful

life as a building, pavement, or other structure – reducing the amount of material that is landfilled and reducing the need for virgin materials in new construction.

 

green design recyclable concreteThe constituents of concrete can be recycled materials, and concrete itself can also be recycled; these materials are usually available locally. Most concrete in urban areas is recycled as fill or road base and not placed in landfills. Concrete pieces from demolished structures can also be reused to protect shorelines, for example in gabion walls or as rip rap.
 
Wood and steel forms are recycled when they become worn or obsolete. Virtually all reinforcing steel is made from recycled steel. Many cement plants burn waste-derived fuels such as spent solvents, used oils, and tires.
 
Recycled concrete can be used as aggregate in new concrete, particularly the coarse portion. When using the recycled concrete as aggregate, the following should be taken into consideration:
 
 
  • Recycled concrete as aggregate will typically have higher absorption and lower specific gravity than natural aggregate and will produce concrete with slightly higher drying shrinkage and creep. These differences become greater with increasing amounts of recycled fine aggregates.
  • Too many recycled fines can also produce a harsh and unworkable mixture. Many transportation departments have found that using 100% coarse recycled aggregate, but only about 10% to 20% recycled fines, works well. The remaining percentage of fines is natural sand.
  • In crushing the concrete, it is difficult to control particle size distribution, meaning that the “aggregate” may fail to meet grading requirements of ASTM C33 – “Standard Specification for Concrete Aggregates”.
  • The chloride content of recycled aggregates is of concern if the material will be used in reinforced concrete. This is particularly an issue if the recycled concrete is from pavements in northern climates where road salt is freely spread in the winter. The alkali content and type of aggregate in the system is probably unknown, and therefore if mixed with unsuitable materials, a risk of alkali-silica reaction is possible.
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Resources
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Download DocumentIn-Place Concrete Pavement Recycling Makes a Green Statement (1997)
Environmental Council of Concrete Organizations, #EV14, 2 pages
Available for free. Bringing the recycling process to the job site saves fuel, saves on wear and tear of roads, and reduces exhaust fumes resulting from the transport of concrete to and from off-site recycling centers. This two-page bulletin presents a case history of an on-site recycling system.
Download DocumentRecycling Concrete Saves Resources, Eliminates Dumping (1997)
Environmmental Council of Concrete Organizations, #EV15, 2 pages
Available for free. This bulletin summarizes some of the considerations involved in recycling concrete into feasible aggregate for new concrete. The bulletin discusses standards, potential contaminants, and cost savings, also highlighting the invaluable savings of landfill space and resources.
Located at External Web SiteConcrete as a Carbon Sink
Liv Haselbach, Associate Professor Civil and Environmental Engineering Washington State University
Located at External Web SiteConstruction Waste Managment Database
Whole Building Design Guide
Enter your geographic information to determine where you can take concrete to be recycled.
Located at External Web SiteOne Block, One Mile, One World: Recycling Pavement with Full-Depth Reclamation
This pocket-size DVD includes a 6-minute video on the benefits and sustainable aspects of using full-depth reclamation (FDR) to rehabilitate deteriorated asphalt pavements. It features construction scenes from a project in Dallas and includes several testimonials highlighting the many sustainable aspects of FDR. Windows format only.
Located at External Web SiteRecycle Concrete Aggregate with Fly ash-A Preliminary Study of a Sustainable Structural Material
American Concrete Pavement Association
Contact the American Concrete Paving Association for receive a copy of this study by the Univ. of California / Berkeley looks at demolition and production of crushed concrete aggregate in conjunction with high volume fly ash as a viable structural concrete in the San Francisco Bay Area. Email rjolly@pavement.com for a free copy.
Located at External Web SiteSlag Cement Association (2006)
An industry resource website dealing with slag cement.