2020, Asphalt Pavements, California, Sustainability

The latest pilot project utilizing recycled plastic in asphalt takes shape in Northern California

The following article is from the the August 3rd issue of the CalAPA Asphalt Insider.

Click here for an article from NBC Bay Area about the same project.

Adding recycled plastic to asphalt was tried out for the first time on a section of the state highway system in Northern California last week, giving Caltrans engineers an opportunity to conduct a real-world evaluation of the concept. It also marked the first time the department paved a highway using 100 percent recycled materials.  

The project comes as the concept of incorporating recycled plastic is gaining attention as a way to address the nation’s recycling crisis. China, long a destination for U.S. recycled materials, has recently curtailed accepting of the material, leaving the waste industry scrambling to find other uses for discarded plastic bottles and other refuse. A CalRecycle report on the issue can be found HERE.  

Meanwhile, a bill promoting the concept of incorporating recycled plastic in asphalt passed the state Senate earlier this year before stalling in the Assembly. The asphalt industry, long a supporter of sustainable practices and recycling, has advocated for more research and field study on the concept so that the environmental and performance aspects of the additive are fully understood.  

The location of last week’s plastic asphalt pavement work was a 1,000-foot section of Highway 162 in Oroville, a semi-rural community in Butte County about 70 miles north of Sacramento. Caltrans estimates that a one-mile segment of pavement using the treatment will recycle about 150,000 plastic bottles.  

“This pilot project underscores the department’s commitment to embracing innovative and cost-effective technologies while advancing sustainability and environmental protection efforts,” Caltrans Director Toks Omishakin said in a news release.  

Promoters of the use of recycled plastic in asphalt roadways, which first gained prominence in Europe, say the product is durable and safe. The pilot project represented the first test on the state highway system in California, although there have been tests conducted on local routes.   “California has set ambitious goals for recycling and other environmental priorities, and meeting them requires innovative and cost-effective solutions,” said state Sen. Ben Hueso, a Democrat who represents parts of San Diego and Imperial counties in the state Legislature. “Using waste plastic that was otherwise destined for a landfill will not only reduce the cost of road repair and construction, but also increase the strength and durability of our roads. As a leader on environmental justice issues, California is uniquely positioned to transform the transportation industry once again by using this new technology that could revolutionize the way we look at recycled plastic.”  

Caltrans currently has a cold in-place (CIR) asphalt recycling program that uses heavy equipment to remove 3- to 6-inches of roadway surface and grind up the asphalt while mixing it with a foamed binding agent made of bitumen. However, Caltrans only permits the CIR process to be used as a roadway base, covered by layer of conventional asphalt produced at a plant. The CIR subcontractor on the project was CalAPA member Pavement Recycling Systems Inc.  

Using new technology developed by TechniSoil Industrial of Redding, Calif., a recycling train of equipment grinds up the top 3 inches of pavement and then mixes the grindings with a liquid plastic polymer binder, which comes from a high amount of recycled, single-use bottles. The new asphalt material is then placed on the top surface of the roadway, eliminating the need for trucks to bring in outside material for a paving operation. By eliminating the need to haul asphalt from the outside, Caltrans said, this process may significantly cut greenhouse gas emissions.   “We’re excited about introducing a new sustainable technology and helping pave the way for utilization of recycled plastics throughout the state,” Caltrans District 3 Director Amarjeet Benipal said in the Caltrans press release. “This process is better for the environment because it keeps plastic bottles out of landfills and helps reduce greenhouse gas emissions and reliance on fossil fuels.” Benipal was the head of the Caltrans Division of Pavements before taking over the regional office that covers 11 Northern California counties, including Sacramento.  

The $3.2 million paving project covers a stretch of Highway 162 between the Feather River and Christian Avenue in Oroville. Lamon Construction Company, Inc. of Yuba City is the prime contractor.  

Tom Pyle, the chief of the Office of Asphalt Pavement for Caltrans, has been closely monitoring various plastic-in-asphalt applications and research, and was closely involved in the pilot project in Oroville. “The plasticized pavement is being investigated to understand the construction, material and environmental characteristics that could make it a specialized tool in the department’s options to repair pavements,” he told Asphalt Insider.  

Asphalt is the world’s most recycled product, and the asphalt industry has long advocated for innovative solutions to make pavements more sustainable. Notably, asphalt pavements made with recycled rubber have been in widespread use in California and have helped divert millions of used vehicle tires from California landfills. A previous Asphalt Insider story devoted to the subject of RHMA in California appeared on April 14, 2016 and can be found HERE.  

Recently, the National Asphalt Pavement Association (NAPA), a CalAPA partner, successfully lobbied for the inclusion in a federal appropriations bill $800,000 to fund a Transportation Research Board study on the use of recycled plastic in asphalt.   The Appropriations Committee supported NAPA’s request for $800,000 for a TRB study on the use of plastic in asphalt. I know you have legislation tracking in California. I wanted you to be aware of this federal effort in case it helps you with the state effort. According to NAPA, the study should identify domestic and international examples of transportation infrastructure projects which have used recycled plastic materials, assess the effectiveness and utility of recycled plastic materials, and assess the extent to which recycled plastic materials are consistent with recognized specifications and standards for transportation infrastructure. the study also will review relevant impacts of recycled plastic materials compared to non-waste plastic materials, assess the health, safety, and environmental impacts of recycled plastic materials on humans and animals, assess the ability of recycled plastic materials to withstand natural disasters and extreme weather events, and assess the potential economic benefits of recycled plastic materials.  

The bill in the California Legislature, SB1238, passed the state Senate on June 26, but its fate in the Assembly is uncertain as the COVID-19 pandemic has greatly curtailed normal legislative activity. CalAPA had expressed concerns about the wording of the bill in its early form, but the author accepted amendments that largely addressed the association’s concerns. More information on the bill can be found HERE. Local media reports about the bill can be found HERE and HERE. A NAPA writeup about overall recycling in the asphalt industry can be found HERE.