Innovative materials and test methods for long-life asphalt pavements

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The short-term objective of our research will be to develop innovative additives and designs to prevent fracture in asphalt due to low temperature and fatigue distress. A secondary objective will be to develop new test methods to simulate chemical aging in service. The long-term objective will be to secure the acceptance of these improvements by government and industry to achieve a more sustainable infrastructure. Our research will focus on several new areas. Our primary interest is to design new copolymers that lower the asphalt yield stress at low temperatures. Today, no such additives exist for asphalt, although virtually all lubricants contain similar materials as pour point depressants. The imminent production of large quantities of lower-quality asphalt derived from oil sands projects means that there is a degree of urgency to this research. A second area will focus on the development of new routes to make styrene-butadiene polymers compatible in asphalt. Chemical methods will be designed to promote grafting of asphalt onto the polymer backbone rather than crosslinking the polymer, which is known to cause a deterioration of properties. A third area of our research will investigate how toughness, interfacial strength, and filler size affect the tertiary creep stage in asphalt. This deformation stage, which is predominant in old pavements, involves a fracture component. Our final area of research relates to the development of improved aging tests. Current laboratory protocols do not replicate the way in which binders chemically age in service; hence improvements are needed in these protocols. If we succeed in developing more failure-resistant asphalts the benefits to Canada are significant. With over 1.4 million two-lane equivalent kilometers of roads, current annual repair costs amount to over $10 billion. It is important that, with such an enormous investment, the full mechanical property potential (e.g., modulus, toughness, yield stress, deformation) of asphalt is better understood. Our research will continue to make important contributions toward this goal. Training obtained in my laboratory will allow students to find jobs in the asphalt materials sector or in closely related polymer, adhesives, and coatings industries.