The roads are the skeleton of Spain. They handle about 90% of passenger traffic and ensure that mail, groceries, ambulances or school buses reach every corner of the country. What happens with this familiar infrastructure happens as with many everyday things that surround us: its smooth functioning is taken for granted. But ensuring their health and longevity, and therefore safe and smooth mobility, is a complex task that requires a heavy investment and a large amount of research and technology.
Because roads, as if they were the human body, age and lose capacity over time. For this reason, public administrations and the private sector are investigating techniques to extend the lifespan of this network. For example: There are already patches that repair themselves and emulsions that eternal youth that prevent deterioration. They are solutions that coexist with the endless reuse of road materials. Most likely, every citizen, without knowing it, drove his car along a road that had a past life.
The almost eternal life of bitumen and stones
The road skin, the top layer, is the first to show signs of exhaustion. Made from a bituminous mixture – stones and bitumen, a petroleum derivative that binds the mixture – it is exposed to the friction of traffic and the most aggressive atmospheric conditions such as sun or rain. That this layer is in perfect condition is vital for the citizen to be able to move with all the guarantees.
José Luis Peña, Technical Director of the Spanish Association of Asphalt Mixture Manufacturers (Asefma), stresses that both ingredients are a perfect example of circular economy: “We don’t know, but we move on reused roads all the time. We have been processing aggregates for decades [las rocas] and bitumen in virgin raw materials. In principle, roads with recycled material are indistinguishable from new ones.”
The scene is typical. As we drive past, we come across a machine that drills and pulverizes the superficial layer of the pavement: this is the beginning of it resurrection. The extracted material is taken to a facility where it is treated and processed. Once completed, its purpose is to make or reinforce any section of road and keep it in optimal condition for traffic. Asefma estimates that 1.9 million tons of asphalt pavement materials were reused in 2020 and expects the number to increase in the coming years.
This technique of reusing materials, known as hot recycling, is mainly used on roads with low and medium traffic density. Others with heavier traffic, like the A-1 or the M-40 in Madrid, still have a high percentage of new resources – rocks and bitumen again – although this is changing, as Peña says: “The new waste law requires more circularity in production”. The experts agree that the quality of this element substitution is so high that people do not notice any difference when driving. Currently, about 20% of road material comes from reuse.
The compound that “rejuvenates” the patch.
This reuse coexists with another emerging and more sophisticated technique. It is that of cold recycling. The University of Delft (Netherlands) was one of the first to study this method, which aims to increase the lifespan of roads without having to change the pavement and with lower maintenance costs. A team of researchers from this center has developed a patch containing millimeter-sized capsules filled with a healing agent. When cracks occur in the pavement, the compound is released and spreads, sealing any cracks in the material. That’s how it works cure.
In Spain, Repsol and Acciona have developed a similar mechanism, already used on our roads, where the pavement itself radiates this connection from the first moment and continuously counteracts deterioration, allowing longer repair times and therefore reducing economic costs in conservation.
Francisco José Lucas Ochoa, responsible for asphalt at Repsol and president of Eurobitume (European Association of Bitumen Producers), compares these compounds to an elixir of life: “Asphalt is like a living being. It is born, it grows and it dies. But it doesn’t die at all. We can revive it. This technology makes it possible to rejuvenate roads. Certain properties lost over time are restored.
New materials and security
Asefma’s José Luis Peña speaks of an “ethical commitment” to increase the lifespan of roads and ward off planned obsolescence, which is already the case with household appliances or mobile phones. But durability isn’t the only workhorse here. The sidewalks are already eco-designed to reduce their impact. For example, work is being done to reduce noise caused by the friction of tires and the road surface, which is particularly important in areas close to cities.
Deborah García Bello, chemist and science communicator, explains that there are increasing sophistications in building materials, such as B. Atmosphere purification systems: “There are asphalts containing photocatalysts that, when exposed to sunlight, are capable of destroying nitrogen oxides. .
Alternatives are also being studied, such as the use of graphene or vegetable waste, materials that could lead to energy savings in manufacturing, something that is now more scrutinized than ever, understands Francisco José Lucas Ochoa of Eurobitume : “We think us in an Industry 4.0 dynamic, the digitization of all processes, so that there is better control over the materials and the value chain, as well as over the emissions generated throughout the process.”
Streets that “sing” and interact
Beyond exploring new materials, roads are experiencing a revolution in connectivity. A report published by the University of Zaragoza collects several experiences that border on science fiction but are already happening on streets around the world. Among the most striking projects are sections of highway already in operation in Taiwan or the United States, with a special relief that plays a melody depending on the speed of the vehicles: if the song Sounds wrong, they warn the driver of a possible speeding. An advance that coexists with new wireless and customizable signals that bounce on vehicles’ dashboards or on drivers’ cellphones; or roads that generate electricity from traffic and can charge the car battery. According to the National Association of Vehicle Sellers, these technological trends will spread in Spain in the coming years, with more than nine million connected cars by 2025.