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From tree trunks to turnpikes: Canadian trials show promise for asphalt supplement

A forestry by-product shows promise for asphalt emissions becoming pulp fiction.

May 17, 2024  By  Jack Burton



Preparing for Canada’s goal to reduce carbon emissions to net zero by 2050 requires key operational decisions from across the country’s many industries. Unique among them is roadbuilding, where asphalt provides both the backbone of the sector’s much-needed infrastructure deliverables and an obstacle to curbing overall emission outputs.  

A 2019 report from Natural Resources Canada found roughly 10 per cent of Canada’s current greenhouse gas emissions come from the extraction and upgrading of crude bitumen from oilsands, working out to roughly 70 million tonnes per year. Environment and Climate Change Canada reported that the asphalt industry in Canada emitted approximately 1.5 million tonnes of CO2-equivalent greenhouse gases in 2019.

A possible solution to asphalt’s emission impacts comes from Canada’s forestry sector, where one company has developed a potential tool in helping the roadbuilding industry meet these goals while continuing to build roads that stand the tests of time and traffic. 

No need to knock on wood

Over the last five years, FPInnovations has harnessed, tested and proven the power of lignin, a by-product of pulp and paper processes, as not only a resilient and sustainable binding supplement in asphalt mixes, but a potential tool in paving Canada’s greener road forward. 

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Lignin, alongside cellulose and hemicellulose, is one of three components of wood; often removed alongside hemicellulose during the process of freeing cellulose fibres in the production of paper or tissue. Through this chemical separation method, known as the kraft process, a substance known as ‘black liquor’ is produced, with approximately seven tonnes of this substance removed for every tonne of pulp produced.

Municipalities from across Canada showed interest in FPInnovations’ lignin-supplemented asphalt solution, including Sturgeon County, Alta. (pictured), Edmonton and Victoria. All photos: FPInnovations

While the residual lignin components of black liquor are often burned by plants to cyclically power their operations, FPInnovations sought to further explore its applications. By using its patented LignoForce process, the company looked to further extract this material and fully harness its binding capabilities – and markedly lower emission rates – as a sustainable supplement to asphalt mixes. 

“We did the lifecycle analysis, and the preliminary case study showed that lignin emits less GHG emissions than bitumen,” said Natacha Mongeau, a manager of business development at FPInnovations. “Specifically, about a 30 per cent reduction can be expected when lignin is added to the asphalt mix.” 

FPInnovations tested lignin’s potential impact on asphalt mixes by creating two solutions. A dry mix was created by dispersing
the lignin throughout the asphalt mixture before adding the bitumen, while a wet mix was created by blending the lignin, bitumen and asphalt simultaneously.  

The dry mix solution was tested on Laval University’s accelerated pavement testing unit, which subjected the hypothetical road to the equivalent of three years’ worth of heavy traffic. Conclusions from these trials showed both the performance and rutting reduction to be at least equivalent to traditional, wholly bitumen-based asphalt mixtures. 

Growth mindset

This commitment to leveraging the tools of the forestry industry into sustainable solutions for a range of economic sectors has been a key focus of the last 20 years of FPInnovations’ century-plus long existence, Mongeau said. 

Despite its promise, “there is currently no lignin being produced in Canada,” according to
Mongeau, though “creating demand for lignin could bring production back.”

With more than 300 employees and a membership of more than 90 stakeholders from across the forestry sector, FPInnovations’ approach to its projects is informed by the goal of creating change, and in turn competitiveness, that extends well beyond the forestry sector and into the economy at large.

 “In general, who we are and our ways of building our projects lies in making sure that we respond to the needs of our member companies and overall economic trends,” said Mongeau. “We see how it would help other industries to reduce their carbon footprint by switching from fossil-based materials to bio-sourced ones.”

FPInnovations’ lignin-asphalt blend exemplifies this overall organizational philosophy; looking beyond surface-level greenwashing practices and toward the need for a sustainable approach to building the transportation infrastructure critical to not only Canada, but the forestry supply chain that keeps FPInnovations’ sector moving forward. 

“We’ve been involved in the vehicle infrastructure interface for a long time […] we’re always evaluating the potential impact of new configurations on the design and performance of resource roads,” said Mongeau. “And now, if we look more particularly at the construction and materials of the roads themselves, bitumen is the one material that has the highest impact on the carbon footprint of roadbuilding.”

Projects across Europe beginning to explore the impacts of lignin-supplemented asphalt mixes caught the attention of FPInnovations, who saw both the potential of the material in roadbuilding applications and, more importantly, the sizeable demand for the lower-emission solutions that it could bring to Canada’s growing transportation construction sector. 

“If you look at the challenges for our industry to invest in lignin production, you need to ensure that you’re going to have a large market where we could we see a high demand for large quantities of lignin,” said Mongeau. “We evaluated this project as having pretty good potential, that would probably trigger enough demand for our industry to invest in the production.”

In the field

Once FPInnovations had secured initial results illustrating the impact of lignin’s asphalt applications, the project attracted the attention of numerous trusted groups and stakeholders across Canada’s industries and governments, who helped move the project forward by testing the mix across the country’s road network. 

Testing on Laval University’s accelerated pavement testing unit subjected the hypothetical road to the equivalent of three years’ worth of heavy traffic, showing lignin-supplemented asphalt to perform equivalently with traditional mixtures.

While the European trials had confirmed the viability of lignin-supplemented asphalt, the main question that FPInnovations sought to answer was whether the roads it made with this mixture could sufficiently stand up to Canada’s more volatile weather patterns. 

Initial lab work was performed in collaboration with École de Technologie Supérieure (ÉTS), with preliminary field testing occurring at Université Laval’s Chair i3C. 

Once its utility was proven, the lignin-supplemented asphalt was used on-site by several asphalt paving companies across the country in their own roadbuilding projects, with participating contractors including Park Paving, Pioneer Construction, Eurovia and Quesnel Paving. 

“They were the ones really trying to help us understand, ‘is this material workable in the road industry, and what is the level of substitution that can be managed?’” Mongeau shared. 

Through this, the FPInnovations team were able to gather some direct feedback from these companies and their in-field workers, in addition to receiving on-site data measuring exactly how this material behaves in real-life applications. 

The project also garnered interest across municipalities wanting to investigate the potential of greener paving solutions, including the City of Victoria, Sturgeon County, Alta. and Edmonton, who all either used this material across city works or offered feedback to FPInnovations on how this mix aligns with their own paving performance requirements. 

To gauge the interest and appetite for this solution industry-wide, one need look no further than the strong funding received from associations and government bodies across the country. 

A range of sources contributed funding to this project, including Natural Resource Canada; B.C.’s Ministry of Forests, Lands, Natural Resource Operations and Rural Development; Ontario’s Centre for Research and Innovation in the Bio-Economy; Nextfor; Quebec’s Ministry of Forests, Wildlife and Parks; and Emissions Reductions Alberta. 

“It was great to see a real collaboration across the industry, because they were all interested in seeing something new coming their way,” said Mongeau. “It was great to see a lot of openness to new ideas and innovation.”

From the trials to in-field testing, including examinations of wear and tear on  stretches of road paved with this mixture in Quebec City and Thunder Bay, results were consistent in showing lignin-supplemented asphalt to be at least equivalent in performance to bitumen-only blends, with results even suggesting slight improvements in higher-temperature conditions.

Investing in the future

While FPInnovations found success in proving lignin’s capabilities as a sustainable asphalt supplement, issues on the supply chain side of lignin production in Canada have put things on hold when it comes to turning their findings into a widely-accessible material solution. 

Sudbury-based Pioneer Construction used FPInnovations’ lignin-modified asphalt in mixtures ranging from 10 to 20 per cent for paving projects across Quebec and British Columbia.

“Unfortunately, there is currently no lignin being produced in Canada,” said Mongeau. “That’s the biggest challenge that I would say exists at this moment, but creating demand for lignin could bring production back.”

Despite this, Mongeau hopes that the results of this project will motivate stakeholders from across both the forestry and roadbuilding industries to come together and invest in the future of producing this substance – and the solutions it brings – across the country. 

“What’s needed now is a positive economic link between these two industries, to come together to support and invest in Canadian lignin production,” Mogeau said. “This is where we need to focus on when it comes to the next steps of making this happen, and making this available for the industry.”

Even with these challenges on the supply side, FPInnovations’ commitment to transforming resources from the forestry sector’s toolbox into solutions for other markets still shines through, with the company continuing to explore lignin’s role across various applications and sectors.

“The challenge with bioproducts is to get benefits and economics working together,” Mongeau shared. “Even when a new solution has been tested and we can demonstrate that it does have the right impact – it needs to be made available at the right price to make it appealing for the industry.” 


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