8 minute read
FEATURE STORY
FEATURE STORY Aggregate, Concrete and Asphalt Producers Lead in Recycling
Charley Rea, Director of Communications, Safety & Technical Services, CalCIMA
Photo provided by North American Recycling and Crushing
Above: North American Recycling and Crushing recycling concrete and asphalt at their Anaheim recycle site.
Late last year, the U.S. EPA commenced a new National Recycling Strategy. There is no better time than now for California to follow and make a renewed commitment to recycling. It only makes sense – it reduces materials in the landfills, conserves natural resources, reduces greenhouse gases, and often saves money!
CalCIMA’s members have led the way in the recycling of aggregates, concrete and asphalt, all of which are common construction materials. The National Recycling Strategy emphasizes the achievement of a circular economy, one where materials can be reused again and again. Fortunately, in the recycling of concrete and asphalt there are many procedures and practices already well established. But the 1 million tons of concrete, asphalt and roofing shingles that go to California landfills speak to the need to do more. "Recycled pavement is stronger, more durable and less expensive to produce than new pavement which saves the end-user money. More importantly, recycling construction materials is simply the right thing to do for the environment," says Aaron Waddell, Account Manager, North American Recycling and Crushing.
The focus on recycling is particularly important in California where we have new infusion of funding for public works from SB 1, The Road Repair and Accountability Act of 2017, and the recently approved federal Infrastructure Investment and Jobs Act (IIJA). Recycling can help extend the value of those infrastructure
Left: North American Recycling and Crushing (NOAM) recycling concrete into 1" fill material at Magic Johnson Park in Los Angeles.
Bottom Left: NOAM’s Cat 988 loading concrete and asphalt into a jaw crusher to process CLII and CMB materials at their Colton recycle site.
Bottom Right: Stacking CLII and CMB from recycled concrete and asphalt at NOAM’s Ontario recycle site.
Photos provided by North American Recycling and Crushing
investments in an environmentally progressive way.
“The recycling of building materials offers so many positive benefits in terms of environmental impact, reduction of cost to the public, greatly reduces landfilling of construction materials while at the same time conserving California’s natural resources. These recycled materials, being used over many years now have proven their engineered value on almost all types of construction projects from roads and bridges to buildings, dams and large structural projects. Our industry is eager to do more,” said Daniel Fritz, Martin Marietta’s CalCIMA Executive Committee and Board Member.
The key to incentivizing the reuse of concrete and asphalt is having specifications for roads, buildings, and structures that allow the use of recycled materials. Specifications are generally written to allow “up to” a certain percentage of recycled material. This means that to the extent the recycled material is available and meets quality requirements it can be used without having to make any special adjustments.
Allowing the use of recycled construction materials expands the market of available materials and thereby achieving greater cost efficiency for public works and other projects. The National Asphalt Pavement Association estimates there was $3.3 billion in savings in the 2019 construction season from the use of reclaimed asphalt pavement (RAP) alone.
“Recycling of construction materials is now more important and beneficial than ever. It has been proven by university research and Caltrans practice that using recycled aggregate, asphalt and concrete produces a product equal in quality to using virgin materials. In addition, it reduces GHG and other air emissions and makes our infrastructure investment funding go further. Simply put, it is a beneficial sustainable practice that should be encouraged by all government leaders,” said Gary Johnson, Vice President, Land and Quarry, for Granite Construction.
These are a few of the ways recycling of concrete and asphalt is being accomplished and where more can be done:
RECYCLED MATERIALS FOR ROAD BASE
Using crushed concrete and asphalt rubble as an aggregate in road base is one of the most sensible and achievable ways to
Above: Granite’s Big Rock plant produces the RAP and recycled plastic mix.
Inset: Core sample of Granite’s mix with RAP & recycled plastic.
Right: Granite Construction produced RAP and recycled plastic mix for Target parking lot. Below: Granite Construction has placed RAP and recycled plastic mix on various projects.
Photos provided by Granite Construction
recycle concrete and asphalt, and reuses a huge amount of material based on volume. Caltrans issued specifications in 2007 that allow up to 100% recycled concrete and asphalt for road base. Caltrans has achieved the optimal level, but further gains can be made with local governments, some of which continue to prohibit or limit use of recycled concrete and asphalt in road base.
RECLAIMED ASPHALT PAVEMENT (RAP) IN ASPHALT PAVEMENTS
A huge area of focus for CalCIMA members has been to increase the allowable percentage of reclaimed asphalt pavement (RAP) in asphalt pavements. This is a particularly important area of recycling, since it not only conserves aggregates but also oil, which is used as a binder for the aggregates in asphalt. Nationally, the use of RAP in asphalt pavements reduces greenhouse gases by 24 million metric tons. Caltrans allows up to 25% RAP in road projects. Legislation sponsored by CalCIMA (Public Law 2012-230) requires Caltrans to develop specifications to allow up to 40% RAP. Specifications have been drafted, but it may be several years until they become common on highway projects.
RAP & LOCAL GOVERNMENTS Despite Caltrans allowing 25% RAP and may be soon increasing that level, many California local governments prohibit use of RAP or are still at a lower level. This is particularly important since most local roads are made of asphalt. The bill AB 2355 (Levine) in 2014 provided incentive for cities and counties to achieve the Caltrans level or better by 2017, but many cities and counties still have not reached that level. Unfortunately, AB 1035 (Salas/Skinner) to further strengthen recycling by local governments last year was not signed into law.
RECYCLED ASPHALT SHINGLES
One promising area is the incorporation of recycled asphalt shingles (RAS). The asphalt content in the shingles can help reduce the reliance on natural sources of oil. Asphalt producers, recyclers, and Caltrans are currently working to complete and test specifications to allow up to 3% RAS in asphalt pavements, as well as combine it with RAP.
RECYCLING PLASTIC ASPHALT An exciting and emerging area is to recycle post-consumer plastic into asphalt. This is a way to reduce from the waste stream plastic that cannot otherwise be recycled while also reducing use of the oil binder in asphalt. A recent test of reusing recycled plastic bags with a 20% RAP mix on an asphalt parking lot appears to have met with success!
RECYCLED CONCRETE AS A PRODUCT
In 2005 and 2013, the Public Resources Code was amended to make clear in law that use of recycled materials in concrete are an acceptable product in accordance with identified specifications and codes. When California’s Green Building Code was launched in 2009, it incorporated producers’ requests to allow for use of recycled materials in concrete— whether aggregates, water, and other materials.
RETURNED PLASTIC CONCRETE
A particularly ground-breaking area of CalCIMA members’ efforts has been to advocate with Caltrans to establish a specification for the use of returned plastic concrete (RPC). This means taking concrete un-used from a job site, but that is still fresh or moist, and remixing into a new batch of concrete. The result was the first-in-the-nation specification to allow up to 15% returned plastic concrete in a mix.
The reuse of returned plastic concrete achieves circularity in recycling--it reuses the cement, aggregates, and water from the original mix. A study commissioned by Caltrans and CalCIMA found a reduction of 15.3% in carbon footprint and a 16.2% reduction in embodied energy from use of returned plastic concrete in a mix. Despite this standard, much work still needs to be done to facilitate the implementation and use of returned plastic concrete.
RECYCLING HARDENED CONCRETE An even greater need for recycling of concrete materials is to allow reuse of hardened concrete as an aggregate in new concrete, since hardened concrete accounts for a large portion of construction material sent to landfills. Progress has been made in allowing its use in making blocks and in sidewalks, including through Caltrans specifications.
The next goal is to allow the use of crushed, hardened concrete in pavements and structures. There is substantial research from the Federal Highway Administration, National Concrete Pavement Technology Center and the National Ready Mixed Concrete Association to support this effort. Caltrans has taken initial steps but needs to do more.
“The new National Recycling Strategy offers further opportunity for California to build on what is currently happening, expanding specifications and uses by state agencies, and ensure local governments utilize those standards, too,” said Marty Hansberger, Director of Technical Services for Holliday Rock and CalCIMA Chairman. n
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