The Economic Times

In 1991, Minnesota mixed factory-made shingle scrap into Highway 25 near Mayer; by late 1995, the asphalt performed at least as well as control sections

Engineers in Minnesota have investigated the potential of recycled asphalt shingles for road construction to mitigate landfill waste. Their trials with manufacturer scrap shingles showed promising initial performance in pavement. Nevertheless, issues like cracking and restrictions on the amount of scrap used arose. The federal highway administration has noted inconsistent shingle quality within road mixtures, adding complexity to their usability in construction.