Pine resin and cashew nuts are among the materials used in the production of bio-based rejuvenators for asphalt

Sustainable Road Construction: BAM researches bio-based Solutions for Sustainable Asphalt Recycling

The Federal Institute for Materials Research and Testing (BAM) is working on a DFG-funded project to make asphalt more sustainable and reusable. By using bio-based rejuvenators, the elastic properties of the material can be maintained even after multiple recycling cycles. The "Postcarbone Road" project is a collaboration between BAM, the Ruhr University Bochum and the Technical University of Berlin with the aim of creating an almost unlimited reuse cycle for reclaimed asphalt.

The challenge of asphalt recycling

Road surfaces need to be renewed approximately every 15 years. Today, much of the old asphalt is recycled. However, with each cycle of reuse, the material hardens, becomes brittle, and is prone to cracking. To counteract this, fresh bitumen, a fossil-based binder, is added. However, this method has several drawbacks: it worsens the carbon footprint due to the use of bitumen and limits the amount that can be incorporated into the asphalt.

"We want to push the limits and show how asphalt can be reused for much longer with sustainable rejuvenators," says Sandra Weigel, a binder expert in road construction and project manager at BAM.

Bio-based alternatives

In order to reduce the use of fossil bitumen, researchers are focusing on rejuvenators derived from natural raw materials such as pine resin or cashew nuts. These are designed to restore the elastic properties of asphalt without compromising its sustainability. However, initial studies show that the effect of these substances is limited to a maximum of four reuse cycles.

New technologies for better results

The long-term effectiveness of the rejuvenators depends crucially on how well they mix with the old bitumen. To investigate this in more detail, BAM is using innovative technologies such as infrared spectroscopy. "Until now, it has not been possible to reliably determine the degree of mixing and therefore to adjust the rejuvenator accordingly," explains Weigel.

With new infrared light guides, researchers can look directly at the chemical properties of the material. This allows the rejuvenators to be precisely adjusted to the reclaimed asphalt, maintaining its elasticity and viscosity over several recycling cycles.

A sustainable future for roads

The Postcarbone Road project could change the face of road construction. The goal is to reuse reclaimed asphalt more often while reducing the use of fossil fuels. These innovations will help conserve resources and improve the carbon footprint of road construction in a sustainable way.

Source: Press release of the Federal Institute for Materials Research and Testing (BAM) "Rejuvenation for roads: BAM investigates how asphalt can be reused more often", October 31, 2024

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