Circularity and sustainability in road construction and maintenance

GWW Magazine in conversation with Bouwend Nederland

"Asphalt is (basically) 100% circular.  We don't throw anything away, we reuse everything except tar asphalt." A statement from Ron Wesseling, Manager of the Bituminous Works Department at Bouwend Nederland. "However, this is responsibly removed from the chain after which some of the cleaned materials can be reused. The point is that we have not agreed on the definition of circularity. We make more asphalt in road construction than we mill from the road. So is that still circular? Of course, we process as much recycled asphalt as possible. That said, as long as more asphalt is needed than is released, the production of new asphalt is always necessary."

With 'Asphalt Impulse', hands are being joined

Wesseling continues his story: "Road authorities, asphalt contractors, suppliers, designers, quality assurance agencies and knowledge institutions will face major challenges in the coming years. Examples of these challenges are giving substance to the circular economy, the Climate Agreement and the Green Deal sustainable GWW 2.0. All preferably with less cost, less disruption and with attention to the economic importance of the asphalt producing and processing companies. This is why the sector has joined forces in the 'Asphalt Impulse' program. Only by working together can we as a sector arrive at solutions to all the issues."

The partners united within Asfalt-Impuls are Rijkswaterstaat, the 12 provinces, municipalities, CROW, TU Delft, University of Twente, Bouwend Nederland (Vakgroep Bitumineuze Werken), independent asphalt producers/contractors, Eurobitume, TNO, Aveco de Bondt, Sweco, Kiwa Nederland, Kiwa KOAC and De Wegenscanners. "Together we are looking for solutions to make asphalt more sustainable," explains Wesseling. "Making it more sustainable is a continuous process. However, innovations that are done must be accepted as solutions. Sometimes provisions get in the way of an innovation. The requirement to use 'proven technology' is a 'chicken and egg' situation. Innovation can only become proven technoloy when it is applied in practice."

Making clear agreements

Sustainability in road construction is mainly understood to mean that asphalt lasts longer and less CO₂-emissions. Wesseling: "But when do you know whether you are working sustainably if there are no clear agreements about it? If you develop an asphalt mixture that lasts 10 times as long on the road, but produces more CO₂-emissions. Is that allowed? We want answers to questions like that. Bouwend Nederland and its Bituminous Works Section are the linking parties in this discussion. We are conducting the discussion with no commercial intent. Actually, we are neutral Switzerland within the group of partners. Bouwend Nederland serves a higher purpose, not only for our own sector, but also for the Netherlands and its citizens. We promote safe working and a level playing field, in a sustainable, circular way -where possible- and want to set standards and define definitions. The gain is in being able to work more efficiently, so on the cost-saving side."

Old systems will be disassembled and the parts that comply with the procedure will be reused.

The nitrogen discussion

Johan Asscheman, Secretary of the Civil Concrete Construction and Specialist Road Construction Section at Bouwend Nederland, addresses the issue surrounding the CO₂-emissions. "Bouwend Nederland is consulting with the government on this, because such a consultation can only be conducted with representatives. That's us, for our sector. The question we ask is 'Where does the interest lie?' The discussion around nitrogen is conducted by the Ministry of Agriculture, that's where the dossier lies. We are in consultation with both the Ministry of Agriculture and the Ministry of Infrastructure and Water Management. However, the problem is ministry-transcending, which is why we welcome the research done by the Remkes Committee. A threshold for construction must be set. Minister Carola Schouten should get to work on this from the government," Asscheman said. "Bouwend Nederland advocates that the minister converts the advice from Remkes' final report into policy as soon as possible and comes up with a threshold value."

Durability in guide rails

When we look at guide rails from a sustainability perspective, Addy van Doorn, chairman of the Guide Rail Committee of the Specialist Roads Construction Section of the Dutch Construction Industry Association (Bouwend Nederland), says: "A working group is active at RWS to look at how we can recycle existing guide rails. A new procedure has been established for this purpose, which will demonstrate that the current model is safe and meets the CE standard. Old systems will be dismantled and the parts that comply with the procedure will be reused. In this way we comply with circular working as much as possible."

Maintenance of paved roads

Within the idea of sustainability, it is desirable to give existing asphalt a longer life, rather than replacing it. Ton Kneepkens of Arcadis (technical partner of the EAB committee within Bouwend Nederland) says: "We have been using emulsion asphalt concrete to give asphalted roads an improved top layer for a long time. The top layer of asphalt wears down due to traffic and weather. Often resulting in texture damage and deformation. With emulsion asphalt concrete, we can repair that top layer; it is like a bituminous coating that optimizes the road. One condition is that the road in question has no serious structural damage; we use emulsion asphalt concrete preventively. The better the surface, the longer the new coating will last. On average, we are talking about a life-extending effect of about 7 or more years. It is a cold technique, the mixture is made on site in a mobile processing unit. The quantity is measured, so no waste. By saving on energy needed in an asphalt plant to make hot asphalt, not having energy-consuming transportation and not having to fire it on site, we reduce CO₂-footprint significantly. And the beauty? After an average of half an hour, the top layer of emulsion asphalt concrete is already passable. Talk about less disruption...".