Technological innovation in the roofing industry recently has focused on roof systems that incorporate environmental features such as cool roofing materials, photovoltaic collectors and surface vegetation. A less visible environmental aspect of roof systems involves the amount of waste generated by their construction and demolition. Asphalt shingle tear-off that ordinarily would be sent to landfills is now more frequently being recycled into hot-mix asphalt (HMA) for road construction.
Early efforts to use asphalt shingles in HMA focused exclusively on scraps or waste from the initial manufacturing process. Manufacturers' shingle waste is easy to combine with HMA because it contains valuable asphalt and aggregates, can be ground, is free of contaminants, and requires simple material delivery or pick-up.
However, using asphalt shingle tear-off in HMA raises some issues. Chief among these is contamination—asbestos, nails, plastic, wood and other debris diminish the material's integrity, and most state paving specifications have not allowed its use. However, research is under way to test the suitability of shingle tear-off in HMA applications and assess its economic value to state departments of transportation and private HMA users.