The first ever trial section of bio-asphalt made from lignin, which covers a 100-metre section of road in the Dutch province of Zeeland, will be officially opened later today. Bitumen in asphalt is usually made purely from petroleum, but in this new asphalt, half of the bitumen has been replaced with lignin, a renewable raw material. If this natural glue material proves successful for use in road surfaces, it will open up the market for bio-asphalt.
It took researchers from Wageningen UR Food & Biobased Research working together with the Dutch Asphalt Knowledge Centre (AKC) just 18 months to put the idea of using lignin as a replacement for bitumen into practice. After finding the right partners in Zeeland (which include the contracting firm H4A, Zeeland Seaports and Economic Impulse Zeeland), a trial section of a road in Sas van Gent in Zeeland was resurfaced.
Lignin used in increasingly more sustainable products
Just last year, researchers from Food & Biobased Research working in the laboratory discovered that lignin could be used as a high-grade biobased replacement for fossil bitumen. “We discovered that lignin had very similar properties to bitumen,” explains Richard Gosselink, coordinator of the Lignin Platform at Wageningen UR. Lignin adheres well, is easy to process and is just as effective as bitumen in terms of UV stability and dimension stability. Dimension stability refers to the fact that the asphalt does not shrink or expand after exposure to rain or sun, continues Gosselink. Lignin has a wide range of potential uses, varying from high-grade applications in products such as vanilla and bio-aromatics (for the chemical industry), to an additive in fuels. Wageningen UR will soon launch a project to explore the possibilities of replacing bitumen in other products (in this case roofing).
There is a huge market for asphalt in the Netherlands, not only for new roads, but also for the upkeep of existing infrastructure. Every year, an estimated 10 million tons of asphalt is produced and used in the road construction industry. Four to five percent of this asphalt is bitumen, which comes to somewhere around 400 to 500 thousand tons. Replacing all or part of this petroleum-based material with lignin would benefit the environment enormously. There is an endless supply of large amounts of lignin. This substance, which gives plants their rigidity, is a by-product of pulp production in the paper industry, and is also available in huge quantities as a residual waste stream in the production of second generation biofuels (ethanol).
Less noise, less fuel?
Three 70-metre sections of road have been resurfaced in Zeeland. One has been covered with regular low-temperature asphalt, another one with low-temperature asphalt using lignin and the last one is a reference section covered with high-temperature asphalt. The trial section is part of a straight road without traffic lights, which will ensure uniform conditions. “We want to see whether the rolling resistance of the asphalt is improved by the lignin,” says Gosselink. “This may reduce the noise and fuel consumption of the traffic on the road, saving even more fossil fuel. But obviously we have to study this carefully before making any claims.”
The trial will last two years, and the project is being funded by the Province of Zeeland and the Ministry of Economic Affairs.