The search for more sustainable materials for road infrastructure construction opens new opportunities to reduce the environmental impact of the sector. One of the most innovative proposals is to incorporate biochar into asphalt mixtures, replacing traditional components with a material made from agricultural and forestry waste.
The development was driven by Agustí i Masoliver (AMSA), Asfaltos y Construcciones Elsan (ELSAN), and the Universitat Politècnica de Catalunya (UPC), whose researchers managed to convert organic waste into a resource capable of reducing the carbon footprint of roads.
The initiative received recognition from the urban challenge “The 21st Century Street Section”, by combining technological innovation, waste utilization, and climate change mitigation strategies through solutions applicable to urban infrastructure.
Agricultural waste turned into an environmental resource
The biochar used in this project is obtained through pyrolysis, a thermal process that transforms biomass in the absence or with very low presence of oxygen, fixing a large part of the carbon in a highly stable solid.
To produce this material, olive pits and pine residues are used, two abundant wastes in many Mediterranean regions that usually have a limited utilization.
Its incorporation into asphalt allows for the valorization of materials that otherwise could degrade or be incinerated, releasing carbon dioxide back into the atmosphere. In this way, agricultural waste management is integrated with sustainable construction.
Roads capable of storing carbon for decades
One of the main advantages of biochar is its ability to immobilize carbon for long periods. While plant residues decompose quickly under natural conditions, biochar retains that carbon for decades within a very stable chemical structure.
When incorporated into the surface layer of the pavement, the carbon previously captured by trees and crops remains retained within the road infrastructure, turning roads into small carbon reservoirs.
Laboratory tests also demonstrated that mixtures made with biochar maintain behavior comparable to conventional asphalts while allowing for a reduction of up to 75% in emissions associated with that part of the pavement.
Olives also provide solutions for the circular economy
In addition to using their pits to manufacture biochar for road construction, olives and their by-products offer numerous applications with environmental benefits. The pomace and pruning residues can be used to produce compost, improving soil fertility and promoting regenerative agriculture.
The olive grove residues also serve as biomass to generate renewable energy, reducing fossil fuel consumption and adding value to materials that were previously considered waste. Additionally, part of these by-products can be incorporated into industrial processes to produce bioplastics, organic fertilizers, or substrates for the restoration of degraded soils.
The comprehensive utilization of olives is an example of a circular economy, as it allows for waste reduction, decrease in greenhouse gas emissions, and the generation of new sustainable products from local resources. This model contributes both to environmental protection and the development of productive activities with less impact on ecosystems.
