Creating better pavements is an ongoing pursuit for the road-building industry. The science behind the work is fascinating, with a constant push to develop roads for greater longevity and endurance. At this year’s annual SHCA Infrastructure Summit and Trade Show, Mike Aurilio, EIT, terminal manager for Yellowline Asphalt Products, presented on the future of pavement and what it means to the industry.
Back in 2020, Aurilio co-authored a paper for his master’s thesis titled High-Performance Pavements: A Focus on Self-healing Asphalt Technologies. His insight into the future of road building is captured well in the paper, which he used as a resource for his presentation at the summit. High-performance pavements are engineered with materials and mixtures that provide superior strength, durability and resistance to traffic and environmental stressors.
“In Canada, there are traditional ways to create high-performance pavements, such as perpetual pavements. They are already used on important projects like a major highway,” said Aurilio. “Road builders are looking for something that they don’t have to worry about for a while.” In his paper, Aurilio explored the state-of-the-art self-healing capabilities of asphalt pavement. Self-healing pavements are currently being researched using methods that leverage asphalt chemistry to reduce crack formation and improve longevity.
Three of those mechanisms being explored include a microcapsule method, where small capsules embedded in the asphalt mix release a “rejuvenator” healing agent into cracks when they break. An induction heating method in which conductive fibres, such as steel wool, are added to the mixture and heated with an induction machine, with the heat softening the asphalt binder and allowing it to flow into and seal the cracks. A microwave heating method is similar to induction heating, in which microwaves heat conductive additives in the pavement, which in turn melt the binder to heal cracks. A Dutch construction company used the induction method in a pavement trial several years ago.
High-performance pavements are engineered with materials and mixtures that provide superior strength, durability and resistance to traffic and environmental stressors.
“They took steel fibres and dispersed them into the pavement,” said Aurilio. “Then they drove over the road with a large radiation source that stimulated the fibre to heat up, which would then activate the self-healing properties that are inherent in the asphalt.” Whether one way works better than others remains to be seen, as the methods are still in the research phase. “All of the methods have their merits and downfalls,” said Aurilio. “The induction heating is where some researchers are worried about the extra heat oxidizing the pavements, causing them to age. The microcapsule method might not activate effectively depending on the dispersion rate.”
However, Aurilio believes all the methods are viable for Canada’s climate. “It depends a lot more on the access to the materials we have than the climate to see which one of those remains the most viable for us,” said Aurilio. Aurilio previously worked on a self-healing method that involved replacing existing pavement polymers with a self-healing polymer and believes that method is equally viable as the others. While Canada’s terrain and climate can be a consideration for using self-healing asphalt, Aurilio says the most significant hurdle to the viability of its potential use remains dependent on the development of these materials.
Aurilio’s 2020 paper on self-healing technologies to produce high-performance asphalt pavements is forward-thinking on how to increase the lifespan of roads using science and technology. It is a snapshot of where the future of the industry could be going, but it will require time.
For the next five to 10 years, the industry will be focused on “reducing carbon emissions and improving our energy usage on pavement construction before we can talk about moving to more advanced materials to extend the life of pavement,” said Aurilio. “I think there is a lot of low-hanging fruit that we can get to first in terms of recycled materials and using more additives that will help us reduce the production temperatures of the asphalt. These additives may also have the added benefit of changing the asphalt chemistry, which would improve the healing properties.”
Martin Charlton Communications is the largest public relations company in Saskatchewan and one of the largest in western Canada.