Plastic Roads, over the Horizon – Doug Walker from Shopper News

Mary Ewell Sustainability, Transportation

China drastically reduced its purchase of the so-called recyclable plastic from wealthier countries in March of 2018. I say “so-called” since much of this plastic still ended up in a landfill either here in the States or abroad. Even when times were better for recycling back in 2015, only 10% of the discarded plastic in the USA made it into the recycling stream! Another 15% of our plastic waste was burned in waste-to-energy facilities, and the remaining 75% went to landfills. China, at that time, was taking half of our plastic refuse and would separate the different plastic types with cheap manual labor. A good portion of that plastic was contaminated and deemed undesirable and was therefore dumped into their landfills as well.  Currently, countries around the globe are seeking alternative ways to deal with the plastic glut.

One alternative has been developed in Scotland by the company MacRebur is using recyclable plastic bottles (#1 Type-PET: polyethylene terephthalate) and plastic shopping bags (HDPE: High Density Poly-Ethylene) as a binder or cement for making their version of a plastic road. Just a crash course: a typical black asphalt road surface material is about 95% crushed stone, gravel and sand with the remaining 5% Bitumen as the black petroleum product used as the glue to bind it all together.  MacRebur is replacing a majority of the Bitumen binder with PET and HDPE plastics. About 20,000 single-use plastic bottles and about 70,000 single-use plastic bags go into 1 ton of their asphalt road building material. Third party testing revealed that this plastic binder is 60% stronger than Bitumen and could lead to a considerably longer roadway life. The company has helped to build roads in New Zealand, the UK, Australia and recently initiated a pilot study road project on the campus of UC San Diego in 2018. All conventional road working equipment can be utilized in their process.

The Technisoil Industrial company out of Redding, California takes it a step further. They not only use recycled PET plastic bottles to replace the Bitumen binder, but have simplified the entire road working machinery as well. Their “Recycling Train” scrapes up the existing road surface and grinds it up, mixes in the new plastic binder on the spot, and lays it down for rolling. The process reduces multiple dump truck travels for removing waste road material and bringing back new road asphalt from a remote mixing plant. Over 1,200,000 recycled bottles would go into one centerline-mile of roadway. The typical road life expectancy should go from 2-5 years to 10 or possibly 20 years due to the extra strength of the plastic binder. This would be a significant energy savings and carbon footprint reduction. A new road in Los Angeles is underway.

Dow Chemical has also gotten into the plastic road concept. They recently built two roads outside of one of their facilities in Texas utilizing a plastic binder which sounds quite similar to that used by MacRebur in Scotland. Both use PET from plastic bottles and HDPE from shopping bags in their asphalt formula.

Another firm in the Netherlands, PlasticRoad, takes this idea a quantum leap further.  They build prefabricated modular road sections made completely out of recycled plastic that lock together like Legos. “The plastic road has a hollow space inside it and can host cables, pipelines, but also rainwater so that the street does not become flooded in case of heavy rainfall.” The option of  embedded sensors or electric vehicle charging systems are conceivable as well. Recycled plastic used as the prime raw material has a significantly lower CO 2 footprint. This is partly due to the longer lifespan of the roadway and the decrease in overall machinery components compared to traditional road constructions.

All of this sounds encouraging. It presents one possible way to deal with some of our stockpiled recycled plastics while tackling the issues of our aging roadway systems. Perhaps at least two of our plastics, PET & HDPE, could come full circle and be viewed as a valuable raw material to assist in reducing our global landfill content & carbon footprint.

Doug Walker is the owner of Walker Cellar Works and Board member of the Monadnock Sustainability Network whose mission is to promote credible, sustainable/”green” practices in the region.