recovery methods

Rubber granulate, powder as an aggregate for rubber-modified asphalt

Asphalt consists of a mixture of bitumen, grit and, if necessary, other additives such as e.g. B. oils or polymers. A common problem with conventional asphalt is that it becomes brittle and brittle at low temperatures, leading to cold cracking and frost damage. On the other hand, asphalt becomes very soft on hot summer days, causing the ruts that are often observed.

Both problems can be mitigated by adding gum powder. Rubber powder or rubber granules ensure sufficient elasticity at very low temperatures and at the same time prevent the road surface from softening too quickly at high temperatures.

Since the 1920s there have always been test tracks with rubber asphalt in Germany, with a wide variety of mixtures and materials being used. A rubber-modified road surface with the brand name Flüster-Asphalt® has been used in Europe since 1981. According to experience reports, the following positive properties can be observed:

• improved drainage ability
• reduced rutting
• Significantly reduced life cycle costs
• lower noise emissions
• Longer road surface life

Despite these undeniably proven advantages, this type of road surface has not yet established itself to the extent that would be desirable in terms of responsible use of the increasingly scarce public funds in our country.
In contrast, numerous large rubber asphalt projects have been implemented in North America over the past fifteen years. Several long-term studies prove both the technical and the economic superiority of rubber asphalt.

Despite the advantages that are obvious, this application is rather a shadowy existence in Germany and the rest of Europe. This is mainly due to the public tender procedures that are customary here. As a rule, the condition of a road surface over a longer period of time is not specified, but mostly the one-off asphalting of a road or motorway. It is in the nature of things that the road construction companies have no incentive to build higher-quality and, above all, durable asphalt pavements with this tendering practice.

If the public authorities change the tendering modalities to the effect that the condition of the road surface is to be tendered over a longer period of time (e.g. 20 years), it would be in the best interest of the road construction company to use a material that is as durable as possible.

This would not only lead to significant savings in road construction costs, but would also have the very pleasant side effect that there would be fewer construction sites and traffic jams in the long term, which would also increase road safety.

Source: Kurt Reschner – Recycling of used tires

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