Since 26 November 2020, the Dutch municipality of Vlissingen has unique metres of asphalt. The construction of this section of the ‘Europaweg Zuid’ consists entirely of lignin-containing asphalt in various layers, some of which are mixed with recycled asphalt. A landmark: never before have all asphalt layers contained lignin. Wageningen Food & Biobased Research developed the technology that made this possible to replace a large proportion of all bitumen in the road.
The CHAPLIN-XL project is part of a large-scale research programme aimed at making road construction more sustainable. The client for the construction of the road section is North Sea Port. This port authority had the very first test strip of lignin-containing asphalt laid in 2015 based on Wageningen technology, developed in collaboration with AKC. Test strips of lignin asphalt are now spread throughout the Netherlands. "Of all these strips, only the top layer contains lignin," explains Richard Gosselink, lignin expert at Wageningen Food & Biobased Research. "Of the road section now laid by construction company H4A, each layer consists of lignin-containing asphalt, partly mixed with recycled asphalt".
Tested in the coming years
In CHAPLIN-XL, Wageningen Food & Biobased Research contributes years of knowledge about lignin raw materials and the correlation between raw material and quality. In this way, lignin asphalt will be tested in practice in the coming years. The knowledge will also be used in the LCA study together with Utrecht University, the coordinator of CHAPLIN-XL. These LCA results - as well as the financial aspects - are important in order to be able to provide future road builders with sound foundations in tenders. The health and safety conditions of the asphalt during production and construction are also mapped out.
Replace all bitumen
Gosselink expects it to be technically possible to gradually replace all bitumen in asphalt with biobased components: "Bitumen consists of various fractions and lignin cannot replace all of them. But in Wageningen we know the composition of bitumen well and we think we can find bio-based alternatives for all components".
The next step is for the lignin asphalt to be recognised as a fully-fledged alternative to 'fossil' asphalt, Gosselink looks ahead: "As soon as owners such as the Directorate-General for Public Works and Water Management have done so, things can go fast. If we succeed in replacing half of the bitumen, it is estimated that we will already save 20% of CO2 emissions. This is because the greenhouse gas is stored in the road surface for a long time. Bear in mind that the asphalt market represents huge volumes, with bitumen consumption of around 12 million tonnes per year in Europe alone. Potentially, therefore, an enormous reduction in CO2 emissions is possible in this sector. ”
Production suitable lignins up
Gosselink acknowledges that a sufficient supply of lignin is a prerequisite for further development: "The production of suitable lignin should be substantially increased in the coming years, for instance with lignin from Dutch origin. This project mainly uses Kraft lignin from Finland, but producer Avantium has already developed a process for the production of lignin from Dutch residual wood. This product will be used next spring for the construction of new test strips in the province of Groningen.”
In CHAPLIN-XL, Wageningen Food & Biobased Research collaborates with Utrecht University, the Asphalt Knowledge Centre (AKC), Avantium Chemicals B.V., Circular & Biobased Delta, H4A and Roelofs Wegenbouw bv. These parties are also part of the broader CHAPLIN consortium.