29 Aug 2019 - To prevent several millions tons of plastic from flushing into the ocean every year, engineers are paving roads with it.
This June, a crew of road workers in Zermatt, an Alpine Swiss town known as a haven for skiing and hiking, laid a new type of road—a plastic one. The road wasn’t built entirely of plastic, of course. But along with the typical paving materials such as stone and sand, Zermatt’s mix included additives from discarded plastic.
Scientists recently estimated that humans have produced 8.3 billion metric tons of plastic to date—25,000 times the weight of the Empire State Building. Seventy-nine percent of that mass ended up in landfills or the ocean. That flow of plastic continues, wreaking havoc in marine ecosystems. Birds and fish can mistake it for food and gobble up the broken shreds, filling their stomachs with debris or choking on it. Large pieces, free-floating in the waves, may help invasive species hitchhike across the ocean. Recently, scientists found that chemicals leaching out of plastic are killing the ocean’s invisible forests—tiny but important photosynthetic bacteria Prochlorococcus that produce about ten percent of all the oxygen we breathe. Despite recycling efforts, eight to 12 million tons of plastic litter still flushes into the ocean every year. According to some estimates, 60 to 80 percent of marine plastic comes from waste sites, industrial and manufacturing sites, stormwater and sewage spills, and even tourist activities. Landfilled plastic isn’t without problems either. As it breaks down, it leaches chemicals into the soil and groundwater that can harm wildlife or make their way into the human food chain.
Scottish company MacRebur is developing a new way to reuse this plastic as paving material. Road surface pavements like tarmac or asphalt are typically made by mixing construction materials such as sand, gravel or stone with bitumen—a black, viscous, hydrocarbon goo generated by oil refineries. The bitumen acts as a binder holding all the particles together. But bitumen and plastic have certain similarities—they are both made from oil and have comparable binding qualities.
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