In Jutland, Denmark, the Horsens asphalt plant shows how Colas is designing industrial facilities for construction materials recycling: high-performance installations that can incorporate large volumes of recycled asphalt pavement (RAP) and support the shift toward a circular economy in road and asphalt recycling.
Producing more—and producing better: capacity, quality and industrial performance
Commissioned in 2021, the Horsens facility replaced a historic asphalt plant that had operated at the port since the 1970s. The objective was clear: improve the site’s overall performance in energy consumption, safety, materials logistics, and production capacity.
“Building a new asphalt plant allows us to start from a blank page.” Klaus Mølgaard, Head of Production, Colas Danmark
Increasing production capacity was only part of the equation. At Horsens, industrial performance is managed end-to-end—from optimized material flows and consistent asphalt mix designs to quality control and the parameters that directly influence energy consumption, especially material moisture levels.
Key figures
| Indicator | Value |
|---|---|
| Plant commissioning | 2021 |
| Annual production (before) | 180,000 tons |
| Annual production (after) | 307,000 tons |
| RAP content in some asphalt mixes | Up to 34% |
In terms of energy, the plant mainly operates on natural gas, with the option to use biogas or renewable electricity when available. Teams monitor energy consumption and heat generation to optimize operations and improve efficiency.
Managing aggregate moisture: a key lever for
energy efficiency
One operational factor plays a major role in asphalt production: moisture.
“Moisture is the enemy of asphalt.” Danni Nilsson, Plant Manager, Horsens asphalt plant
To reduce its impact, aggregates are stored under covered sheds to protect them from rain, and the plant is equipped with a high-performance dryer. By lowering moisture levels, the site reduces heating requirements, improves overall energy efficiency, and supports higher levels of recycled materials in asphalt mixes.
RAP: when asphalt recycling becomes a strategic resource
In Denmark, recycled asphalt pavement (RAP) has become a key resource for the road construction industry. The principle is simple: material milled from existing pavements is recovered, analyzed, and reintroduced into the production of new asphalt mixtures—supporting construction materials recycling at scale and strengthening materials and asphalt mixes</a> strategies.
From milling to reuse: the RAP value chain
RAP materials come from road construction projects carried out by Colas and other industry players. They are then reused in new asphalt production through carefully engineered formulations.
This asphalt recycling process relies on several steps:
- collection and logistics of reclaimed materials
- quality control through sampling and laboratory analysis
- optimization of asphalt mix designs (aggregate gradation, binders, and production processes)
- maintaining consistent performance once the asphalt is installed on the road
High recycling rates
Denmark is one of the most advanced markets for integrating recycled asphalt pavement into asphalt production.
Across the Colas Group, asphalt mixes contained an average of 18.7% RAP in 2023. In Denmark, that share reaches around 34% recycled materials, depending on performance requirements and applications.
“RAP is now our most important raw material.” Martin Ole Korsgaard, Technical Manager, Colas Danmark
Addressing both environmental and economic challenges
This strategy is also shaped by Denmark’s geological context. The country has gravel pits but no hard rock quarries, meaning some materials—such as granite—must be imported, mainly from Norway or Sweden.
In this context, asphalt recycling delivers both environmental and economic benefits:
- reducing the use of virgin aggregates
- lowering the amount of bitumen required in certain asphalt mixes
- reducing transportation needs and securing material supply chains
Supported by a favorable regulatory framework, this approach contributes directly to Colas’ carbon reduction objectives and complements initiatives to reduce the impact of bitumen binders.
Innovation and co-development with local authorities
Increasing RAP content without compromising asphalt performance requires continuous technical expertise. Each year, the Colas Danmark laboratory analyzes several thousand samples to characterize materials and refine mix designs.
This innovation dynamic is also built through close collaboration with public clients. Colas Danmark regularly conducts pilot projects with municipalities and with the Danish Road Directorate (Vejdirektoratet).
The goal is to test and validate solutions that improve the sustainability of road infrastructure, such as low rolling resistance asphalt, as well as innovations combining recycled materials with partially plant-based binders, including the Vegeroad product range reflecting innovation for more sustainable roads.
Denmark: a circular road laboratory for the Colas Group
At Horsens and across Denmark, asphalt recycling is no longer experimental. It is now part of a mature industrial model built on quality control, traceability, and continuous performance improvement.
The experience gained in Denmark helps inform the Group’s strategy worldwide. It shows that high levels of recycled materials can be integrated into asphalt production while maintaining demanding performance standards for road infrastructure.
Learn more
This article is adapted from Issue 53 of ROUTES magazine (May 2025).
To explore more about materials, innovation, and the circular economy in road construction, discover our thematic features and additional insights on our website.
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