There’s a bin of glass bottles on the curbside. But what if there was no use for them after they went in the recycling bin? Would they end up in the landfill after all? According to Rick Smith, the technical sales manager for Aero Aggregates, in Eddystone, PA approxiamtely 30% of glass has been recycled and 70% has gone to a landfill. However, a new use for recycled glass, known as foam glass, may provide both a use and market for recycled glass which can keep it out of the landfill. It is lightweight, easy to move, and highly inusulating, and can be used as a fill for building foundations.
Smith said foam glass is made of recycled material as opposed to synthetic foam or polystyrene, which are made from oil and plastic. Smith also said foam glass is more fire resistant than other insulation materials. While gravel, which is a common fill is a renewable resource, Smith said foam glass is lighter, easier to move and puts less pressure on the soil. Torsten Dworshak, who does marketing and sales for Glavel based in St. Albans, VT, which hopes to be in prodution in six months, said that foam glass has compressive strength and thermal insulation properties. In addition to fill, Smith said it can also be used for filtration, hydroponics, and agricultural uses. He said it can release water back into the soil as it dries out. Dworshak said another use for foam glass is also green roof applications and noted that it doesn’t put too much stress on buildings.
To make the product, the glass is ground up and mixed with a foaming agent, such as silicon carbide or a limetone based agent. It is is then spread on a layer of fiberglass and baked. While the material bakes the foaming agent creates air bubbles, which gives it a highly insulating value. Smith said the limestone based agent causes the air bubbles to be connected, while the the silicon carbide causes air bubbles to be separate. As a result, the material doesn’t absorb water which was better for construction materials, which was why his company uses silicon carbide. Dworshak said his company was considering using either calcium carbonate or glycerin as the foaming agent.
Smith said foam glass was first made in Germany in the 1980’s and has been in widespread use in Scandanavia for approximately three decades. To date, it has not been in common use in the U.S., but he hopes that will change in the coming years.
Smith said one of the difficulties with recycling glass is that it is heavy and hard to ship. As pressure on resources increases, finding creative and innovative ways to use recyclable items becomes more and more imperative. Foam glass has the potential to provide a use for recycled glass and offer an alternative to synthetic materials.
The Nature Journal 