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Rises in construction and asphalt binder costs, as well as the growing pressures on landfills, have contributed to the increased use of tear-off scrap shingles (TOSS) and manufacturer waste scrap shingles (MWSS) into hot-mixed asphalt (HMA) pavement mixtures. This research project was undertaken to address the responsible incorporation of recycled asphalt shingles (RAS) into HMA pavement mixtures to ensure environmental benefits are realized and pavement durability is retained or improved. The research consisted of a literature review, extensive laboratory testing and field evaluations of in service RAS/RAP HMA pavements. Binder testing established a strong correlation between the new asphalt binder to total asphalt binder ratio and the extracted high/low binder performance grade temperatures. Dynamic modulus testing on HMA mixtures proved to be an invaluable tool in comparing the effects of RAS and RAP on mixture properties across a wide range of temperatures. Field performance appeared to validate the laboratory findings in some instances.

Expansion and maintenance of roadway infrastructure creates a demand for high quality paving aggregates. Taconite industry rock and tailings are a potential source of virgin paving aggregates. Currently there is limited information available for implementing these products in construction design specifications. Preliminary information of product performance within current design constraints is valuable to both state design engineers and to future pooled-fund studies. This information can identify the potential for using these products in surface courses or possibly for use in rich-bottom leveling layers. This study examined the viability of utilizing these products in the Minnesota Department of Transportation (Mn/DOT) Superpave bituminous mixture design specifications. As part of the study 40 laboratory specimens were produced from 11 asphalt mixtures and then evaluated for asphalt content, air voids, and aggregate gradation. This report summarizes the results of the laboratory mixture evaluation.