What is RWS’s vision for sustainable asphalt?
Jeroen: “Together with the Ministry of Infrastructure and Water Management, Rijkswaterstaat has developed a strategy for working in a climate-neutral and circular manner in all government infrastructure projects by 2030. For circular working we look at three goals, as developed by Platform Circular Building ’23: protecting the environment, material stocks and value. This can be achieved in different ways. This so-called CIP strategy (Towards climate-neutral and circular government infrastructure projects) is organised into ‘transition paths’, the transition path for road surfacing being one of them. Sustainable asphalt can be achieved through reuse, life extension (rejuvenation), production at lower temperatures and the use of bio-based binders.
How are you working at RWS to make this happen?
Liz: “We encourage the transition to sustainable asphalt in various ways. For example, we provide financial contributions to research and we ourselves construct so-called test and trial areas on the roads that we manage. We do this so that we can test in practice whether these innovative sustainable mixtures meet our current set of requirements for safety and other performances, for example. We also use the Environmental Cost Indicator in our contracts. This encourages the contractor to supply more and more sustainable asphalt.
What role do you see in this for lignin and more specifically CHAPLIN?
Liz: “The bitumen balance at the moment is not yet balanced, so new material will have to be added. At the moment we are still using fresh bitumen based on petroleum. However, in view of RWS’s objectives we want to use renewable bio-based raw materials. An additional interesting aspect is that bio-based raw materials bind CO2 and fix it for a longer period of time. Moreover, lignin is also released as a residual flow from the paper industry that we could reuse to a high degree. We would like to explore this further, which is why we are participating in CHAPLIN.”
What are the reasons for RWS to participate in CHAPLIN?
Jeroen: “One of the aims of our CE directive is to protect material stocks, this also means increasing the security of supply of these raw materials. For bitumen, the security of supply of the right quality seems to be declining. It is therefore important to diversify the supply, among other things through innovation. We want to ensure that lignin asphalt can be used as an option by 2030. Because validating innovations simply takes a lot of time, it is necessary to accelerate this relatively immature development. For us, this is the main reason for joining CHAPLIN. In addition, because the first insights indicate that lignin as a binding agent in asphalt also contributes to the CE-goal of protecting the environment through the improved environmental performance of lignin asphalt.”
What milestones do you see on the way to 2030 and 2050?
Liz: “A real milestone for me is the moment when we, as RWS, no longer purchase any fossil bitumen for use in our roads. I’m also looking forward to the moment when we can construct our first lignin test section, in preparation for the validation of lignin as a binding agent in asphalt.” Jeroen adds: “We also want to accelerate by actively retrieving this knowledge from other (European) road authorities and sharing the knowledge developed in the Netherlands. I see the start of such a cooperation as an important milestone to scale up lignin applications in asphalt.”
More background information can be found on the RWS website: