Martínez-Toledo et al., in their study published in Materials Today Sustainability, explored the potential of using biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More derived from European hazelnut shells as a sustainable modifier for asphalt binder. The researchers investigated the impact of slow pyrolysis conditionsThe conditions under which pyrolysis takes place, such as temperature, heating rate, and residence time, can significantly affect the properties of the biochar produced.   More, specifically temperature and residence timeResidence time refers to the duration that the biomass is heated during the pyrolysis process. The residence time can influence the properties of the biochar produced.   More, on the physicochemical and antioxidant properties of the biochar. Their findings suggest that biochar obtained from hazelnut shells has the potential to enhance the performance and sustainability of asphalt roads.  

The excessive use of asphalt pavements has led to significant deterioration due to heavy traffic and harsh environmental conditions, particularly rising temperatures associated with climate change. Modifying asphalt binder with bio-additives derived from agricultural waste has gained attention as a sustainable solution. Hazelnut shells, a significant by-product of the hazelnut industry, have shown promise as a source of biochar due to their high lignin content and antioxidant properties.  

The study employed a factorial design with varying pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperatures and residence times to produce biochar. They found that pyrolysis conditions significantly influenced the chemical composition and microstructure of the biochar. Higher temperatures and longer residence times resulted in increased carbon content and enhanced porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More. The biochar also exhibited antioxidant capacity, retaining a significant portion of the antioxidant properties present in the hazelnut shells.  

Confocal laser microscopy revealed a uniform distribution of biochar in the asphalt binder, indicating good compatibility between the two materials. Chemical interactions between the biochar and the binder were observed through FT-IR and XPS analyses, particularly in samples pyrolyzed at 300°C and 550°C for 1 hour. These findings suggest that biochar from hazelnut shells can effectively modify asphalt binder, potentially leading to improved performance and durability of asphalt pavements.  This research contributes to the growing body of knowledge on sustainable materials for road construction. By utilizing waste from the hazelnut industry, this approach promotes a circular economy and reduces the environmental impact of asphalt production. The use of biochar as a modifier for asphalt binder offers a promising pathway towards more sustainable and resilient road infrastructure.  

Source: Martínez-Toledo, C., Valdés-Vidal, G., Calabi-Floody, A., González, M. E., Ruiz, A., Mignolet-Garrido, C., & Norambuena-Contreras, J. (2025). Optimising Slow Pyrolysis Parameters to Enhance Biochar European Hazelnut Shell as a Biobased Asphalt Modifier. Materials Today Sustainability. https://doi.org/10.1016/j.mtsust.2025.101087