Recycling Asphalt Roofing Shingles in Asphalt Pavements

Project summary:

Up to one-fifth of construction and demolition waste in the Twin Cities metropolitan area consists of tear-off shingle scrap (TOSS), which is post-consumer roofing material removed when a home is re-roofed. Of the 60,000 tons of TOSS generated annually in the metro region, more than 90 percent is potentially recyclable for use in asphalt pavement. At the beginning of 2010, the Minnesota Department of Transportation released a draft specification that would allow up to 5 percent TOSS to be used in asphalt. To fine-tune this specification, this study investigated how the addition of TOSS affects the low-temperature properties of asphalt mixtures used for paving roads, a well as the potential environmental benefits of using recycled materials in asphalt. The research showed that adding up to 3 percent TOSS resulted in no statistically significant differences in the low-temperature properties of the most commonly used asphalt mixtures. A preliminary environmental life-cycle assessment showed that asphalt mixtures that contain recycled shingles and reclaimed asphalt pavement consume less energy and produce fewer greenhouse gas emissions during the production process compared with an asphalt mixture without recycled material. The greatest reduction in these environmental impacts was estimated for the mixtures that used the most recycled materials. Based on this analysis, all of the available TOSS in the Twin Cities metro area could potentially be recycled for use in asphalt pavement in the region. It is anticipated that the results of this research will provide critical information for the development of a standard specification for the use of scrap tear-off shingles in asphalt pavements in Minnesota.