Minnesota Lab Research on Tear-Off Shingle Scrap 

The Minnesota Office of Environmental Assistance (OEA ), via a time sensitive grant through Dan Krivit and Associates (DKA), funded a Minnesota Lab Study Project.  This OEA project directly complemented a parallel study sponsored by the Missouri Department of Transportation (MoDOT ).  (See MoDOT research project ).

The goal of the OEA Project was to complete testing of samples adequate to allow the Minnesota Department of Transportation (Mn/DOT ) to recommend changes to the State hot mix asphalt (HMA) pavement specifications that would allow the use of tear-off shingles in HMA as a normal business practice.  The Minnesota OEA project included the following objectives: 

1. Develop a study methodology to compare the relative impacts of tear-off vs. manufacturer RAS on HMA quality and performance.  The methodology should use standard practices and methods whenever possible such that the tests can be replicated by other research in the future.
2. Measure total asphalt cement (AC) content (percent) and PG binder grade variability in tear-off shingle scrap compared to manufacturer shingle scrap and other control samples (i.e., Mn/DOT lab extraction and PG grading).
3. Conduct a controlled set of HMA laboratory analysis to provide empirical data of tear-off vs. manufacturer shingles and other control samples on HMA strength (i.e., U of M indirect tensile tests). 
4. Conduct a controlled set of recycled asphalt shingles (RAS) analyses to develop standard practices and methods to measure relative amounts of deleterious materials in the ground / screened RAS product (before incorporating into HMA).
5. Analyze the data results, and if these indicate that tear-offs are safe and feasible, recommend a new Mn/DOT specification allowing tear-off shingles in HMA.  The Mn/DOT Bituminous Engineer will consider developing such a new recycled shingle specification if the results indicate the tear-off-derived HMA is equivalent to, or better than, manufacturer-derived HMA.