Spanish law adopts bitumen with rubber

In article no. 540 of that regulation it was then read: “In works where the use of the product resulting from the crushing of used tires is technically and economically viable, priority will be given to such materials.” The order applies to new construction road projects and the reconstruction of existing ones, as well as to other types of works, namely structural rehabilitation.

It costs twice as much, but it resists

Modified bitumen made from recycled rubber costs approximately twice as much as conventional bitumen, but this does not result in an increase in the cost of the work, the recycling companies claim. All told, construction costs are similar, given the high resistance of that bitumen to crack propagation. In this way it is possible to reduce the costs of maintaining the floor. In addition, the thickness used in mixtures with recycled rubber is up to half that used in conventional mixtures. The first successful experience of incorporating tire waste into asphalt was carried out in the United States by Charles MacDonald, a former employee of the Federal Roads Office and Materials Testing supervisor for the city of Phoenix, Arizona. That is why it is called ‘MacDonald process’ or ‘Phoenix process’. On about 70 percent of roads in the US state of Arizona, modified bitumen is made from recycled rubber.

Deflected for Burning

A significant amount of tires collected in Portugal – 22.9 percent – is sent for burning or energy recovery, practiced at Secil de Maceira, in Leiria. Secil do Outão, in Setúbal, also applied for a license to co-incinerate the ‘chips’ (non-recyclable fraction) of the tires. However, after some inquiries, the Environmental Monitoring Committee of that unit concluded that the ‘chips’ were, after all, crushed tires, that is, raw material for the recycling industries. Neither Valorpneu nor the Waste Institute has yet clarified how it was possible that more than four thousand tons of ‘chips’ and tire pellets were sent from a recycling unit to Secil do Outão. The non-recyclable fraction – essentially composed of textile, with some rubber, and steel wires – represents about 25 percent of the total weight of the tire. The appropriate destination will be landfill or incineration with energy recovery.