The Recycling and Greening of Asphalt
This month on April 22, nations around the world will celebrate Earth Day. The theme of this year’s event—environmental and climate literacy—got us thinking about the extraordinary steps taken by the construction industry towards being greener. In fact, for many of us, the shift is literally happening right beneath our feet.
When you’re walking down the street or driving to work it probably hasn’t occurred to you that asphalt is one of the most-recycled products in the United States. That’s right—in 2015, more than 99% of asphalt pavement reclaimed from roads and parking lots was available for use in new pavements, helping to keep more than 74 million tons of old asphalt from the landfill. In contrast, only 67% of aluminum cans and 66.8% of paper are recycled in the U.S.
Modern asphalts also incorporate old tires into the making of new rubberized pavements, helping to keep 9.3 million tires out of landfills in 2015 alone. We’re exceptionally proud of the reputation we’ve built for producing long-lasting tires, however, eventually every tire has its time. According to the EPA, a whopping 80% of used tires in our country are given another shot at usefulness, and it makes us happy to think that our tires will get to live a second life in our streets, sidewalks, parking lots, and playgrounds.
The composition of roof shingles makes them ideal for asphalt, keeping 1.9 million tons of waste shingles (approximately 15% of the total supply) from landfills in 2015. Glass has also been used since the ‘70s as a substitute for aggregates because it's cheaper than sand and gravel. Further adding to the appeal of “glassphalt” is that the glass does not need to be sorted by color for use in pavement (reducing energy and cost), and the use of both shingles and glass helps to reduce consumption of other aggregates.
Green innovation is happening in the paving industry, too. The emergence of warm-mix asphalt (asphalt produced using temperatures 30 to 120 degrees cooler than traditional asphalt) has allowed producers to reduce the amount of fuel used and lower their carbon footprint. Furthermore, warm-mix asphalt cools at a lower rate, enabling pavers to extend their season. The warm-mix surface can also be placed faster than traditional asphalt—which means less labor and machine use is required.
As of 2015, the United States had 2.6 million miles of paved roads, and over 94% of them are asphalt. This Earth Day, as we think about environmental and climate literacy, take a second to look beneath your feet and admire the asphalt for its “green” achievement. And who knows…there may be what once was one of our tires under there, too!