India, Sept. 30 -- A plastic water bottle takes a few seconds to use and a long time to break down. A 2021 review in Sustainability by researchers at Universiti Putra Malaysia and Misurata University notes that PET (polyethylene terephthalate), the plastic used in drink bottles, is not biodegradable and is a real environmental hazard. So what do you do with that waste? Some engineers say the answer might be under our feet.

In 2019, Los Angeles announced a pilot project to introduce a new way to fix worn-down streets. The material was first laid in December 2020 on a stretch of 1st Street between Grand Avenue and Hope Street downtown. The process was developed by TechniSoil Industrial, according to Caltrans. It involves the use of recycle...