USask-City of Saskatoon project aims to build winter-resistant roadways

Dr. Haithem Soliman (PhD), an associate professor in Civil, Geological and Environmental Engineering in the University of Saskatchewan (USask) College of Engineering, is partnering with the City of Saskatoon to look for ways to build roads that will be less affected by cold temperatures.

Here are five facts about road construction, and how this joint research project could change the way we approach road construction in Saskatchewan.

One of the biggest struggles when constructing roadways in cold temperatures is the most obvious – asphalt, the most common material for road construction, needs to be hot when it is “poured” out to build a new road.

“At high temperature it becomes soft. At low temperature it becomes brittle. So, to build a good road we need to have the asphalt delivered to the construction site and it needs to be compacted at a high temperature to achieve good density, good stiffness and durability,” Soliman said.

If typical asphalt is not laid out at the optimum conditions, there are many variables that will make the roadway less durable.

If the asphalt is not hot enough, it will not settle at the proper density and have high air voids, which can fill with water and then freeze and crack in cold temperatures. Soliman compared it to freezing a can of soda or a sealed bottle of water – the liquid expands when frozen, causing fractures.

It’s not the only cause for damage to roadways, but Soliman pointed to it as a cause for concern that can create potholes and chipping in roads.

As Soliman puts it, it’s not just the cold that makes road construction and repair difficult, but the inconsistency of Canadian weather. Short summers mean a short construction season, and many construction projects need to make their way into September and October to be completed.

To get around those constraints, Soliman said they either need to change their construction methods or change the materials being used on roads, which is what this research tends to explore.

“If we have a condition that we need to pave at cold air temperatures, we can recommend different materials or different mix designs,” Soliman said. “That is the objective.”

The joint USask-City of Saskatoon project is supported by the Research Junction initiative, which gives funding to research projects of importance to Saskatoon residents.

“This research initiative will help the city better understand how paving in colder temperatures affects the service life of our community roadways, how other jurisdictions approach this challenge, and what tools and methods are most effective under cooler conditions,” said Matthew Hiltz, the City of Saskatoon asset preservation manager. “Ultimately, we’re trying to find ways to extend the construction window before winter arrives.”

Soliman said warm mix asphalt can be poured and compacted at lower temperatures than traditional asphalt. His research team will be exploring other additives they could use in the asphalt mix that could allow it to be laid and compacted at lower temperatures still, allowing for more flexibility and durability for roadway construction.

Soliman’s research at USask involves using recycled materials in roadway construction, such as plastic waste products. The broad aim of his research is to find not only more efficient, but also more sustainable solutions for roadway construction.

It’s something he has explored in the past with non-asphalt roads, by using unique infrastructure at USask. A truck load simulator that was built at the Multi-purpOse Soil Testing (MOST) Facility at USask uses cutting-edge technology to assess the effectiveness of differently built unpaved roadways under a variety of conditions.

Soliman and Hiltz both said they were excited to pool the unique resources and expertise of the city and the university to find solutions for future construction projects.

“This is my first direct research collaboration with the City of Saskatoon, and we’re having a good connection in terms of pavement research,” he said.