In an effort to great a green, sustainable concrete, researchers in India are developing a concrete mix that replaces sand with used and treated plastic shopping bags.
According to a report in the Jagran Post
A pilot study ... has already replaced sand with 10 percent plastic in concrete, but it gave rise to issues like minor reduction in compressive strength of the mix ... "What we are trying to establish is whether the plastic-mix in concrete will emerge stronger, say, 10 years later. Would it be more susceptible to fire? In case of fire, will it emit fumes that could be more risky for the inhabitants?" [Purnanand Savoikar, a professor at the Goa Engineering College], noted.