The Environmental Impact of Nano-Coatings: Sustainability in Action

Reuse has more impact than sustainable new materials

Research shows that reuse is always the most effective strategy for emission reduction when faced with the choice between reuse of existing pavements (Practical reuse) or replacement with a sustainable new material (Sustainable replacement). Comparing these scenarios shows that reuse can save an additional 18-21% of emissions for Concrete tiles, Concrete paving stones and Curbs compared to the emission reduction achieved by replacement with sustainable new materials.

For Brick, the current practice already represents the practical scenario of 85% reuse. Including sustainable replacement for the remaining 15% on a project basis is therefore a feasible strategy to achieve further emission reduction. However, as indicated, an increase in the reuse percentage to 95% is also beneficial for Brick, as this measure reduces emissions by another 13% compared to sustainable replacement without increased reuse percentages.

Circular pavements are key to climate mitigation
How do these scenarios play out in Amsterdam’s current road maintenance cycle? First of all, the analysis clearly shows the importance of circular pavements for climate mitigation. The worst-case scenario without structural reuse of paving materials (which is not unusual for an owner of public assets) would generate over 62 kton CO2-eq emissions in the current five-year maintenance cycle in Amsterdam. That is the equivalent of the emissions generated by the energy consumption of over 16,800 households in one year – roughly five entire city districts the size of the Kinkerbuurt.

By applying circular strategies, this can be reduced by 87.5%, meaning that in a five-year cycle a total of at least 54.4 kton CO2-eq emissions can be avoided – or roughly 11 kton CO2-eq emissions can be avoided per year. This impact is comparable to making the energy consumption of an entire city district climate neutral, such as taking a neighborhood the size of the Kinkerbuurt off gas. This can be achieved by having just one asset owner apply a relatively simple measure to just four types of materials (excluding asphalt).

Acceleration of circularity needed to realize climate policy goals for infrastructure
The Amsterdam policy goal of reducing greenhouse gas emissions by 55% by 2030, compared to the reference year 1990, cannot be achieved in the normal way. However, the goal becomes achievable with the gradual adoption of the practical reuse case in more and more maintenance projects. In 2021, emissions in Amsterdam (across all sectors) were roughly equal to the amount of emissions in 1990. Since not much has changed in road maintenance practices between 2021 and 2022, we can safely assume that emissions in the business-as-usual scenario for road maintenance in 2022 represent this baseline and therefore need to be reduced by 55% in 2030. This means that if we stick to business as usual, the CO2 budget will be exceeded by 55%.

Research shows that the current emission trajectory represents a significant deviation from the policy objectives. The figure highlights the average annual greenhouse gas emissions if each scenario were adopted as standard practice. If the reuse practice were to be applied as standard practice in all maintenance projects, the resulting emissions would be well within the stated policy objectives. However, you cannot scale up a relatively new practice overnight and apply it to all maintenance projects.

To address this issue, we propose an approach to stay within the annual carbon budget. Our analysis shows that the reuse practice is the most desirable route to achieve this goal. To achieve the emission reduction target, as it has already been partially implemented and offers a large potential for emission savings. By adapting this circular approach for at least 13.6% of the total maintenance demand from 2024 onwards, and scaling it up annually with an additional 13.6% of reuse projects until 2030, the target can be achieved.

In other words, the municipality must increase the reuse percentage for all four pavement types to 85%, which would create an additional 13.6% of the total maintenance requirement per year until 2030. This is certainly ambitious, but feasible.

Conclusion and recommendations

Reuse is the most effective strategy: Compared to sustainable replacement, reuse can result in up to 21% additional emission reduction.
Circular pavements have a huge impact: By implementing circular strategies, the CO2 emissions from road maintenance in Amsterdam can be reduced by 87.5%.
A phased approach is necessary: ​​By increasing the annual reuse percentage by 13.6%, Amsterdam can stay within the climate objectives.
Drastically reduce material use: Circular strategies can reduce material use by 96.7%, which is equivalent to saving six Eiffel Towers of raw materials per year.
By following this approach, Amsterdam can make a crucial contribution to both the circular and climate objectives.