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New ways for old wheels

Spanish refinery Cepsa headed up the team that devised a cutting-edge recycling method to use old tyres to repair the country's roads.

Some 9,000 residents were evacuated from their homes while hundreds of firefighters spent days trying to put out the blaze. A year on, Spaniards still remember what the fire at Seseña, 45 kilometres from the Spanish capital Madrid, looked like. Environmentalists had long warned of the risks at Europe's largest tyre dump, where 5 million tyres were accumulated over nine years.

The authorities don't know how the fire was started but the environmental catastrophe reminded everyone why old tyres from lorries and cars need to be responsibly treated. Since they're big and don't rot down, one good way found to deal with old tyres is to shred them to mix with asphalt to pave roads - a form of recycling that Spain's energy company Cepsa decided to make more efficient during EUREKA network project Powder Road.

"Existing techniques are often very good with lorry tyres because they contain more natural rubber and so are more elastic, but the methods aren't as effective for car tyres," explained Vicente Pérez, technical director at the company's asphalts unit. With about 46 million cars on Germany's roads alone, there is a clear financial and environmental incentive to find a method that works better for car tyres.

Dream team

To research the whole process, Cepsa, which already manufactures other bitumen products from tyre dust, worked with existing contacts: Spanish company Gestión Medioambiental de Neumáticos (GMN), which shreds tyres, Germany's Pallmann Maschinenfabrik, which makes the shredders, and Spanish builder COMSA which spreads asphalts on the roads. The group was an ideal combination to test the shredding of the tyres, the possible bitumen mixtures and their performances on roads.

"There are higher and higher standards being demanded from roads today - they need to be durable because there's more traffic on them and they also have to meet environmental targets, such as reducing noise levels," explained Pérez.

Through careful testing the partners came up with bitumen that met those standards - and was also cheaper and better than others on the market. The rubber particles in it didn't have to be ground as finely as those in other products and the final bitumen didn't have to be heated to as high a temperature - factors which reduced the cost of the process. The product is also more stable and the need for additives in it is lower.

The research and development has already boosted the reputation of the three partners in a demanding market

The partners presented their results at one of the sector's most respected trade fairs, ASEFMA, in Spain, and are now exploring commercialisation. The research and development has already boosted the reputation of the three in a demanding market, said Pérez. With European economies like Spain's beginning to recover after a long crisis, roads are being repaired again and infrastructure projects are restarting. Powder Road has put the partners in a position to tap into the upturn.

The partners also used their research to develop another new product, a hard bitumen with rubber, to be used in high resistance asphalt mixes, such as those needed in port areas. They successfully tested Flexodur Am, as they named it, at the port of Tarragona, in North East Spain, with very good results. “It’s much more flexible than ordinary bitumen so resists better,” said Pérez.

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