Sustainable and circular road construction

The CO₂-goals are clear. We must drastically reduce the use of fossil raw materials, including in road construction and, more specifically, the asphalt industry. This requires innovation. However, practice shows that large public clients still take too much of a top-down approach to innovation. That only slows things down. A bottom-up approach, on the other hand, is much more efficient and actually accelerates the necessary sustainable transition in road construction.

Parties like the Department of Public Works and other public commissioners generally take a very long time to validate and approve new initiatives. This is because of their top-down approach. Things have to be looked at ad infinitum. Because of this way of working, the government is lagging tremendously behind with developments. Whereas the SME, in which the Asphalt Knowledge Center operates, is much more concerned with product development on the basis of functional requirements and at the same time tests against regulations. Bottom-up, in other words. This approach means that SMEs are miles ahead when it comes to reducing fossil raw materials and achieving climate goals.

Eventually we will have to say goodbye to the fossil binder bitumen in asphalt. We are now focusing mainly on the development of bio-based alternatives. And we are very far down that road. Petroleum is nothing but compressed plant residues. The molecules of petroleum and bitumen are essentially the same as those of plants or trees. They still have to be processed to make the biobased material do exactly what bitumen does, but that's it. In the meantime, this has been quite successful on a laboratory scale, in cooperation with Wageningen University and others. So we are in the right direction, but we are not there yet. It is expected to take another ten to fifteen years to fully develop and scale it up to industrial level.

Another example, starting in 2025, asphalt producers are going to phase out the current hot mix asphalt mixture. From then on, the processing temperature will be a maximum of 140 degrees Celsius, Hot Mix Asphalt. We have had such a mixture ready for 15 years and it meets the functional and legal requirements. It provides a CO₂-reduction of up to 40%. It is already being successfully applied in municipalities and provinces. Driven by political pressure, we now see that the Department of Public Works is also slowly starting to make a move and is becoming open to applying Warm Mix Asphalt.

When it comes to circularity, we see some governments demanding that a road construction project be 100% circular. So that is not possible. The demand for new asphalt to be produced is greater than what is released in milling asphalt. So that's going to be a problem in the long run. Just like the supply of crushed stone. In Germany, several quarries are being closed for environmental reasons. That also has a big impact in time. So we have to think very carefully about how we deal with released materials. It is a serious challenge and is going to be very exciting, because you see that the market is not yet sufficiently involved.

If you extend that line, I expect that within now and twenty years our roads will be worked up in situ. Technically, it can already be done in a single pass. Indeed, on the toll roads in Italy it has been the most normal thing in the world for ten years. Because here a commercial party owns the road and they are open to scientifically based alternatives. In the Netherlands, all roads are owned by the government, which generally operates in a risk-averse and conservative way. If the government does not set clear goals and stands in the way of innovation with regulations, market parties will not invest many tens of millions. The government must therefore be clear, accept sustainable and circular alternatives and adjust regulations accordingly. Then together we can achieve the climate goals with a flourish.