It’s on the news, it’s in your kitchen bins, and it’s in our landfills and waterways. The prevalence of plastics in our world continues to grow, offering convenience to manufacturers and consumers, yet also bringing its own set of challenges when it comes to disposal and recycling.
The technological forces in the world of asphalt never cease to amaze us in their quest for innovation. They are now making great strides in the utilization of what were once the discards of recycling and turning them into stronger, longer lasting roadways.
Toby McCartney has been a pioneer in this research. He was first inspired to explore the possibilities after a trip to India. Residents there would fill potholes with plastic waste and then light it on fire. The melting plastics would fill in and harden in the hole, creating a makeshift solution. When he returned to his home of Scotland, he began to do extensive research into the possibilities. Formal scientific advances of that basic premise have been occurring in India as well.
How does it work? The refuse from post consumer packaging such as water bottles, plastic bags, and plastic farming waste is shredded or formed into pellets and incorporated into bitumen, the oily black binding agent which holds the gravel, sand, and other organic materials together. The benefits of this process include the fact that the sorting efforts needed are not prohibitively discriminating—much of what is not typically recycled due to complicated separation and cleaning procedures can be used.
The average asphalt mix is comprised of roughly 90% aggregate and 10% bitumen. By replacing the bitumen with 6-20% plastic waste, the roadway can be formulated for specific conditions such as extreme heat or repeated freeze and thaw cycles. For every ton of asphalt generated, a whopping 20,000 plastic bottles and 70,000 plastic bags can be incorporated.
Plasticizing our asphalt has other benefits, as well. Take, for instance, modular plastic road construction in which portions of road are constructed off site and placed as needed. These have an advantage of providing space underneath the roadways for drainage or other components and can be easily placed and replaced.
As with much in our world, when it comes to technology, there are pros and cons. The naysayers of the advances in plastic roadways argue that it merely hides the problem of plastics and still brings with it concerns over leakage of chemicals, fumes emitted during processing, and a false sense of repurpose. It will be interesting to see how things continue to unfold and what balances are achieved between environmental efforts and consumer trends.
So, what do you think? Plastic asphalt—good or ill?