Asphalt and Plastics

Crushing It, One Bottle at a Time

Do you ever wonder where plastic bottles and bags end up after you drop them into the recycling bin? As it turns out, you might be walking and driving on the answer. As our dear readers of Love2Pave know, the world of asphalt is an amazing place where technology and science meet the roadways, parking lots, and driveways of the country. In recent years, the paving industry has joined forces with the ever-changing realm of recycling, and the dynamic duo is quite unstoppable. 

There is a lot to love about plastic: its durability, its high melting point, slow decomposition rate, and resistance to UV rays means it can seemingly last forever. Which is good…and bad. How can those qualities be put to optimal use while, simultaneously, ensuring they don’t end up in our landfills? Asphalt is the answer (or at least one of them). 

Asphalt 101

Before we can fully dive into the fun stuff, let’s refresh our memories as to what asphalt actually is. What we call “asphalt” is actually shortened from “asphalt concrete,” and is made up of a mineral aggregate (tiny rocks or gravel) mixed together with bitumen. Bitumen, a crude oil derivative, is the glue that holds all the aggregate together. Think of it as the marshmallow to the Rice Krispie treat, the caramel to the popcorn, the egg to the meatloaf…you get the idea. Take loose, gravelly material, mix it with the binder, and poof! You have a substance that can be poured and smoothed into a roadway or parking lot.

Alright, we got that out of the way. On to the interesting part.

Where Plastics Come In

Remember a few paragraphs ago when we were talking about all those stellar qualities of plastics? Durability, slow decomposition rate, resistance to UV rays, etc? Some really smart people have found a way to maximize those qualities by adding plastics to the bitumen—the binder—in asphalt. In fact, they’ve been able to replace around 6% (by weight) of the bitumen with plastics. 

Most asphalt is already recycled! The main ingredient of the aggregate used in paving is typically aggregate that has already been used. Reclaimed pavement is sorted, crushed, and mixed back into new asphalt—this is called Recycled Asphalt Product (RAP). Combine that with the plastics-enhanced binder, and we’re well on our way to making pavement that much more environmentally friendly.

How Does it Work?

Put very simply (we don’t even really understand it 100%), single-use plastics (like plastic bags and bottles) are ground up into granules and melted into the asphalt binder, thus replacing a good portion of what would otherwise be made up of petroleum-based bitumen. So, not only does this method help keep plastics out of our landfills, it also cuts down on how much crude oil is used in the asphalt paving process. Win, win!

To keep things even more environmentally pleasing, testing has shown no increase in leachable materials into the substrate beneath or surrounding the material, as well as no increase in fume generation when using recycled plastics as a modifier. (Basically, plastics-enhanced asphalt doesn’t seem to be any more harmful for the surrounding environment and air than normal 100% bitumen-based asphalt.) Another win!

• An average plastic bag takes more than 500 years to degrade in a landfill. 
• An average passenger car produces around 4.6 tons of carbon dioxide in a single year.
• When paving a 20,000 square foot parking lot (about the size of a typical strip mall), using the plastics-modified/extended asphalt can save up to 166,300 plastic bottles from landfills.
• When paving a 100,000 square foot lot (the size of a large shopping center or HOA), using the plastics-modified/extended asphalt can offset up to 27.5 tons of carbon dioxide (effectively nullifying the carbon emissions of 6 cars-worth of CO2).
• Black Diamond typically places around 30,000 tons of asphalt in a year. This means we can offset 275 tons of CO2 and save 9.96 million plastic bottles from ending up in landfills…each year.

The Non-Environmental Benefits

All studies done around this subject so far have shown this asphalt to be a superior product. The testing done with bitumen that has been modified and extended with plastic has been shown to deliver a final result that is more resistant to deformation, less likely to fracture (which ultimately means less water entering the surface), and more durable across the lifespan of the asphalt. Win, win, win.

As the technology has developed, the sophistication of the formulas has also dramatically increased. This recycling wonder product can now be formulated to address key concerns regarding the anticipated use. For instance, if a surface is going to be frequented by heavy load vehicles, a formula can be chosen that is structurally denser and stiffer to reduce rutting. It makes you wonder…what will they come up with next?

Black Diamond is happy to play our part in the recycling efforts of our world by constantly improving our ability to put down a better, more environmentally friendly product. It’s one way we all can contribute to a greener reality. Are you ready to go Green with us