Roof replacements generate large volumes of discarded asphalt shingles, most of which are sent to landfills. In the early 1990s, two Minnesota engineers examined whether some of that waste could instead be incorporated into road construction. Minnesota Department of Transportation researchers David Janisch and Curt Turgeon documented that a 1991-1996 overlay on Highway 25 south of Mayer contained sections made of scrap shingles. By the end of 1995, those sections were performing at least as well as the control section. These findings are notable given that recycled shingles remain a real and sometimes contested part of American road-building.
A test road with a twist
