Roof shingles have a lifespan. Eventually they start to crack or corrode, and aren’t up to the job of keeping a home dry. In fact, 10 million tons of shingles are ripped off roofs in the U.S. every year and account for almost 5 percent of all landfill material. But twenty states and green-minded contractors are working to turn this roofing waste into something more productive. Asphalt shingles actually make great road material. It’s a win-win when fewer shingles go to landfills, and public roads are cheaper to pave.