Plastic can take between 20 and 600 years to decompose, and every year, Americans throw away over 33.6 million tons of it. As we increase plastic production and throw out more of it every year, engineers have found new ways to use plastic, including road construction.
Roads can be made from recycled plastic and aggregates. Most asphalt roads are made with aggregate and bitumen, but recycled plastic can replace the bitumen, thus reducing construction costs, producing better quality roads, and removing plastic from landfills.
So, let’s get down to the hard facts and discuss how we can use recycled plastic to make better, more eco-friendly roads across the world. I’ll also tell you all about the potential drawbacks to recycled roads.
Some Countries and Cities Already Have Recycled Plastic Roads
Recycled plastic roads are a relatively new invention, but they’ve seen success all over the world.
Engineers in India were the first to develop recycled plastic roads. In India, 15,000 tonnes (15,000,000 kg) of plastic are produced daily, most of which hasn’t been recycled.
In the early 2000s, Dr. Rajagopalan Vasudevan, an engineering and chemistry professor, developed the first recycled plastic roads. By 2015, the Indian government made it mandatory for all engineers and construction workers to use plastic on most roads and highways in India.
Starting in 2019, many countries, including Ghana, South Africa, Australia, the Netherlands, and the United States, took the lead from India and began designing and installing recycled plastic roads.
These roads have seen tons of success and have fueled the new global engineering trend of building more durable, longer-lasting, recycled roads.
You can find most of these roads in residential areas and bike paths.
However, the technology behind recycled roads is still relatively new, and there isn’t much evidence on how long these roads will last in the long term.
Because of this lack of evidence, most governments outside of India haven’t started using plastic roads for main roads or highways. Still, many engineers hope that, as the recycled streets see more use in neighborhoods and on bike paths, they’ll get more support from the government.
Recycled Plastic Roads Are Made From Aggregate and Plastic
Most asphalt roads contain 90 to 95% aggregate. The aggregate gives the road bulk, and it’s usually made of natural materials such as sand, gravel, and limestone. These organic materials are essential for durable roads and paths, and luckily, they’re all-natural.
Bitumen makes up the rest of the road. Bitumen is a black tar that’s extracted from distilled petroleum or fossil fuels. This sticky liquid or resin-like solid glues a road together, and since bitumen is an oil, it also repels water. In addition, it is flexible, which can prevent cracking and breakage in streets made using bitumen.
While bitumen is a crucial component for road construction, it isn’t environmentally friendly. In fact, it is one of the major sources of air pollution in cities. However, we have discovered a new substitute that could cut down on waste in our landfills and oceans.
Because bitumen is a petroleum-based material, it’s also plastic. Plastics are made when petroleum is heated up.
When moderately hot temperatures are applied to petroleum, a chemical reaction occurs. In this reaction, the carbon molecules in the petroleum bond together, resulting in a durable, waterproof material – plastic.
However, since bitumen is a type of resin and plastic, pre-used and recycled plastics can replace this tar, reducing the number of raw fossil fuels necessary to make and repair roads.
Recycled Plastic Is Cheaper Than Bitumen
Recycled plastic isn’t cheaper than fresh bitumen in two ways:
Bitumen, on average, costs $0.57 for every 1 kg (2.20 lbs) used. However, the total cost of using 1 kg (2.20 pounds) of recycled plastics in road construction is $0.16, including processing expenses. For long stretches of road, that makes for significant savings.
Additionally, those up-front costs don’t include the reduced need for repairs or the ability to recycle the aggregate that comes with using plastic instead of bitumen.
Since there isn’t any long-term evidence for how long the recycled plastic roads will last, there aren’t any hard statistics for the savings that plastic roads offer.
However, most road engineers estimate that recycled roads will last at least three times as long as standard asphalt roads, although other engineers suggest that the new streets will last 8 to 13 times as long.
Asphalt roads, on average, last 18 years, so according to experts, new recycled roads should last at least 54 to 144 years. That’s a long time to wait! However, if these claims check out, we can expect roads to last much longer, and we won’t see as many potholes or cracks on our daily drives.
So, if the government switches to recycled plastic, our roads will likely last longer and get repaired faster since it won’t cost as much to keep them in good shape.
Plastic Roads Could Make Road Repairs Easier
Recycled plastic roads are significantly easier to repair, too.
For example, in Los Angeles, engineers have used recycled plastic to repair roads without adding any more aggregate.
When the road cracks, crumbles, or breaks, engineers remove the broken section of the road. Then, they grind up the old asphalt and mix it with recycled PET plastic, creating a 100% recycled road.
In other places like the Netherlands, recycled plastic roads are modular, making road replacements just as easy as connecting legos.
These roads are made on a recycled steel frame that includes an open section for power lines, plumbing pipes, and other infrastructural components, making road repairs simpler than ever. These hollow channels also make room for an irrigation system that prevents flooding.
To install them, workers place the road panels into a paved channel.
When the road wears down or needs to be replaced, a crane can lift one small section out, then put a new one in within minutes. So, these plastic roads not only make repairs simple and less expensive, but they also cut down on installation time and labor costs.
For more information on how modular recycled plastic roads could make repairing roads quicker and easier, check out this YouTube video from Mashable. It goes through the Netherlands’ use of recycled roads:
Recycled Plastic Could Make the Roads Waterproof
Using recycled plastic on roads can make them stronger and cheaper to produce. However, recycled roads also repel water better than standard bitumen asphalt, reducing flooding and safety hazards related to stormwater.
Recycled plastic, especially polyethylene, is an excellent waterproofing material. Polyethylene plastics like PET and HDPE are commonly used in water bottles, milk jugs, condiment bottles, and cosmetic packaging. So, it’s already waterproof.
When you add plastic to roads, they become more water-resistant, and in the right quantities, more oil-resistant, making roads safer to drive on, even in flooding conditions.
Plastic’s water resistance could also help prevent road foundations from washing away over time, minimizing the need for road repairs.
Recycled Plastic Roads Reduce Our Carbon Footprint
Naturally, using recycled plastic instead of brand new plastic is better for the environment. However, how much of a difference can reusing old materials make?
Engineers who design 100% recycled roads have calculated that their streets result in a 90% reduction in carbon emissions compared to standard asphalt road construction. That’s a huge percentage, and it only counts for the first installation.
Over time, if the roads hold up the way they’re supposed to, they’ll minimize roadmakers’ carbon footprints even more since engineers can recycle all of the materials used to repair the streets.
In South Africa, where the government first installed recycled plastic roads in 2019, engineers used asphalt that contained the equivalent of 100 milk bottles worth of high-density polyethylene in every meter (3.28 ft) of road. All added up, they used over 40,000 milk bottles’ worth of plastic.
In addition, it’s essential to note that, although most plastics release toxins when they’re heated, the temperatures used to make recycled plastic roads are low enough to ensure the safety of the laborers and engineers that work with them.
According to Dr. Vasudevan, a significant leader in India’s revolutionary transition to recycled plastic roads, plastic only becomes a gas “if it’s heated at temperatures above 270°C (518°F).”
To make roads, Dr. Vasudevan and other engineers worldwide only heat the plastics to 77°C (170.6°F). Doing so, they turn the plastics into a liquid, preventing them from releasing harmful chemicals into the air.
Plastic Roads May Leach Chemicals
Many scientists and engineers have a significant qualm about using recycled plastics on roads. Plastics usually contain chemicals that prevent the materials from decomposing, and these chemicals are often toxic.
These chemicals usually ensure that the material will stay intact for years to come, which is convenient if you want to store water or food in them. However, when this plastic containing phthalates, lead, cadmium, or other toxic chemicals, is used to make roads, the chemicals may leach from the plastic, introducing more toxins to our environment.
Under cool and dark conditions, these plastics won’t release the chemicals that make them so harmful to the environment. However, when exposed to sunlight, constant wear and tear, and running water, the plastics could erode, leaching poisonous toxins into the atmosphere.
Still, the argument can be made that, left in a landfill or an ocean, these plastics would release the chemicals anyway. However, by introducing them to American roadways, we might destroy some ecosystems that have yet been undamaged by plastic waste.
There may be ways for engineers to extract or counteract these chemicals, but as of right now, most recycled plastic roads contain them.
So, scientists are still at work learning how to prevent these chemicals from harming the environment, and it might be several years before they have a breakthrough.
Recycled Roads Need More Work Before They Hit the Highway
With all of the benefits of recycled plastic roads, you might wonder why your local streets aren’t made out of recycled plastic by now.
However, plastic roads need more trial before we can assume that they’ll safely hold cars moving at high speeds and stand up to years of wear underneath the weight of massive freight trucks.
In one test performed by the California Department of Transportation, recycled plastic roads seemed to warp under the weight of freight trucks.
In their test, a truck drove over a 1,000-foot (304.8 m) testing strip of recycled plastic asphalt. As it passed, the experts on-site recorded that the road seemed unsafe and moved when one truck drove over it.
So, when we design highways that can withstand years of hard wear and tons of weight from passing freighters, we still need some time to find the magic formula for recycled roads.
However, plenty of plastic roads have stood up to light wear in residential areas and on sidewalks. These roads and sidewalks have held up since their installation in 2019 in countries like the Netherlands, Ghana, and South Africa.
So, we’re moving in the right direction.
Many states in the USA are currently testing new road-making procedures that include recycled plastics, and many are seeing success.
Some city roads in Missouri and California have moved beyond the testing period, and recycled roads are generally on the rise as people have become more concerned about the accumulation of plastic waste in our oceans and landfills. So, keep an eye out for recycled roads coming to your area over the next few years!
Recycled plastic roads are a relatively new invention, and scientists and engineers are still refining the materials and processes used to make them sturdy and reliable. Still, recycled roads have many benefits, from cost to longevity, so you should expect many states in the US to start installing them in residential areas soon.