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...
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