When the City of New York repaved a section of Fifth Avenue 20 years ago with something called glassphalt, the pavement sparkled from tiny flecks of recycled glass. Glassphalt — an aggregate mix using crushed glass — has been used in other parts of the U.S. and across the world in the 20 years since. In fact, it first arose in the 1970s as a potential way to recycle the considerable volume of amber, blue, yellow, green and clear glass bottles in the waste stream. Annually, approximately seven million tons of glass are disposed of in landfills. The problem with recycling glass is that mixed colors in the recycling stream mean that a specific color can’t be achieved — clear bottles can’t use amber material, for example. That’s what led to exploration of other uses of glass, where color wouldn't be an issue. Researchers found that by mixing it into pavement, where color was irrelevant, it could work functionally and possibly in a cost-effective way. The results 20 years later show that the glass used to pave Fifth Avenue showed required much less maintenance compared to projects constructed with gravel, and the glassphalt road had no potholes. The absence of potholes should be enough to sell any city on paving their roads with recycled glass.
