Spanish Scientists Produce Environmentally Friendly Asphalt from Wheat Straw, Promising Greener and More Durable Roads

WPB writes that researchers at the University of Huelva have come up with a new technique of constructing roads that could change the way asphalt is produced and used all over the world. By incorporating wheat straw into asphalt mixtures, the scientists have created an eco-friendly product that not only reduces environmental impact but also increases durability and heat resistance.

Highways have been made for decades of petroleum-based derivatives that generated a false sense of simplicity while hiding their environmental cost. Not only the production of asphalt but also the friction generated by daily traffic are significant sources of pollution. In this regard, the University of Huelva's Center for Technology of Chemical Products and Processes (Pro2TecS) has presented the GreenAsphalt project with the aim of developing more eco-efficient road surfaces from renewable resources.

In 2023, the inaugural trial stretch of road constructed from this novel "bio-asphalt" was completed. Unlike conventional asphalt, which requires high temperatures during processing and fossil-derived polymers, the new material had been processed at 150 °C and blended with virgin aggregates, reclaimed products, bio-binders, and rubber powder. The process is energy-saving and reduces production emissions.

At the base of the breakthrough is a novel use of wheat straw cellulose, which is ubiquitous in paper making. Through a chemical reaction known as silication, the researchers transformed cellulose to make it water repellent and compatible with oils and bitumen. The transformation produced an additive that is stable, can strengthen asphalt, as well as industrial lubricants.

Bitumen, the dense, viscous binder in asphalt, has conventionally been obtained from petroleum. Over 90% of the modifiers that are mixed in to improve its performance are fossil fuel-based. The Spanish team has replaced them with renewable cellulose-based chemicals. The process, project leader José Enrique Martín Alfonso states, provides a biodegradable alternative with similar, and in some cases better, performance compared to conventional additives.

The potential of this research extends beyond roads. Industrial lubricants, which are often formulated with lithium, may also be enhanced by cellulose-based substitutes. Lithium, once a relatively overlooked element, has become scarce and expensive due to its critical application in battery production. The wheat-derived additive offers a cheap, environmentally friendly substitute that has demonstrated better wear resistance than lithium-based greases.

The experimental tests conducted by the researchers at the University of Huelva included thermal analysis, friction tests, and microscopic analysis. The tests indicate that recycled asphalt possesses greater elasticity, improved heat resistance, and reduced deformation under heavy traffic. While results are promising, the scientists note that there remains ongoing improvement, particularly in cellulose pulp size and structure optimization for achieving greater interactions in asphalt and lubricants.

The effect of this study is profound. By lessening the reliance on petroleum and lithium, the project is a step in the direction of more sustainable infrastructure. Roads made using renewable bio-asphalt can shrink carbon footprints, lower dependence on finite resources, and endure longer under harsh conditions.

Briefly, the University of Huelva's wheat straw asphalt project demonstrates how agricultural waste can be transformed into high-value infrastructure materials. As research and real-world testing move forward, the technology stands to shape a new generation of roads—stronger, more flexible, and more sustainable than ever imagined.

By Bitumenmag

Asphalt, Bitumen, Technology