Grant: Discovery Grants Program - Individual

Asphalt pavements constructed today rarely last as long as they did 50 years ago. Some regions have seen lifespans shrink by as much as 50-60% (Auditor General of Ontario, 2016), largely due to poor practices and materials. The decline is due to heavier traffic, anomalous weather, the use of inadequate specifications, and the "greening" of our roads through ill conceived use of recycled materials. Across Canada, ~$120 billion-worth of roads are in fair, poor or very poor state (Canadian Infrastructure Report Card, 2019). My group has developed rigorous specification standards and implemented them to great effect. For instance, one major Ontario municipality lost 63% of its pavement lifespan between 1980 and 2014, going from an average of 30 years in 1980 to an intolerable 11 years in 2014, for a pavement condition index of 50%. However, since 2016 it has bounced back to an average of 25 years by implementing test methods developed through our research. We now need to investigate how to mitigate aging with effective additives to further reduce cracking. Our short-term objective is to understand how to better assess thermo-reversible aging by monitoring the precipitation of waxes and asphaltenes in asphalt at various temperatures. In a first for this sector, we will continue to use innovative infrared (IR) spectroscopy methods developed to monitor wax and asphaltene precipitation in crude oils for asphalt. We will study gel formation by measuring properties for asphalt that has been aged to varying degrees with sophisticated rheological methods. Factors defining the onset of gelation will provide more accurate measures of when asphalt becomes prone to cracking than those currently used for specification grading. We will also study irreversible aging to add evidence to longstanding disputes in the literature on how asphalts react with oxygen to harden over time. We will use oxygen-17 nuclear magnetic resonance (NMR) spectroscopy and derivative IR, again for the first time in this sector, together with more conventional proton, carbon-13 and silicon-29 NMR, in one and two dimensions. We will use isotope enriched protective groups where feasible. As a long-term goal, we will evaluate the use of wax inhibitors, dispersants, antioxidants and unconventional base asphalts to mitigate aging, and use the spectroscopic, thermal and rheological analysis techniques to assess the effectiveness of our innovative anti-aging additives. This research program will reduce cracking distress in pavements and provide more sustainable roads. Governments, as well as the general public in Canada, will achieve enormous savings on future infrastructure expenditures, reduce travel delays and improve road safety. The embedded training program, in which equity, diversity, and inclusion are part of daily routine, will give students a highly desirable set of transferable skills and sought-after knowledge that will give them a competitive edge in the work force.