The Dutch province of Gelderland will take a further step towards the greening of its road network on 12 July when a stretch of cycling path alongside the N315 between Neede and Rietmolen is given a top layer made of asphalt that contains lignin and recycled asphalt. Together with the AKC (Asphalt Knowledge Centre), Wageningen Food & Biobased Research has developed the technology that allows a large part of the bitumen in the asphalt to be replaced by lignin.
The placement of this demo road is part of a large-scale research programme called CHAPLIN-TKI, which aims to increase the sustainability of road construction. The commissioning client for the cycling path is the Province of Gelderland. NTP, contractor for roads, soil, water, energy and consulting, is responsible for the production of the asphalt prepared at its plant in Ommen and its application on the path.
"Lignin to replace bitumen"
"Lignin-containing asphalt will replace fossil bitumen as the adhesive in asphalt in the years to come," predicts Richard Gosselink, lignin expert at Wageningen Food & Biobased Research and coordinator of the CHAPLIN-TKI project. "Test roads like these are required to make the technology market-ready. Previous research showed that asphalt with lignin performs just as well as conventional asphalt in terms of functionality. Every application demands a specific composition of the asphalt. Being very familiar with the properties of the different types of lignin we are able to provide roadbuilders with good advice."
Significant potential environmental benefits
The main advantage of lignin as an alternative to bitumen is that it has a far more favourable environmental profile. "This is an important reason for us to switch our focus to replacing bitumen in asphalt with lignin," says Jeroen Buijs, project leader Development, Advice and Quality at NTP. "The potential environmental benefits are significant: replacing half of the bitumen would result in savings of 30 to 50 percent on CO2 emissions. In the Netherlands alone this would involve a reduction of some 300,000 tonnes of bitumen a year."
Roadbuilders need test results
NTP will start placing the new, sustainable top layer on 12 July. The CHAPLIN-TKI consortium will start performing performance analyses on the asphalt as soon as production and construction gets underway, explains Gosselink. "Roadbuilders need these test results to properly substantiate their choice for sustainable asphalt in tenders." Factors here include the technical and functional properties, lifespan, environmental aspects (lifecycle analysis, LCA) and costs. "I expect lignin-containing asphalt to be an approved and widely applied product in the Netherlands within five years."
Wageningen Food & Biobased Research is working on the CHAPLIN-TKI project with the Asphalt Knowledge Centre (AKC), TNO, H4A, NTP, Circular Biobased Delta, University Utrecht, Dura Vermeer, Latexfalt, Vertoro and Avantium Chemicals BV. These parties are also part of the wider CHAPLIN consortium. More than 20 test segments with lignin-containing asphalt have already been placed in the Netherlands, including in the provinces of Zeeland and Groningen. The Wageningen Campus has had a lignin cycling path featuring various types of lignin since 2017.
