The uses for recycled rubber are far more varied than one might think when looking at a tyre at the end of its useful life. After processing, a single tyre can yield rubber, steel and textile fibres, each with very different end uses. The difference lies in how each fraction is recovered and the condition in which it enters the next stage of the process.
Here at Silmisa, as manufacturers of machinery for waste treatment and tyre recycling, we’ll tell you what can be done with these materials.
Main uses and applications of reclaimed rubber
Rubber retains some very interesting properties even after a tyre has reached the end of its useful life. It remains a strong, flexible material capable of absorbing impacts, vibrations and some noise. That is why it can be used in a wide variety of products.
Recycled rubber products vary depending on the size, cleanliness and characteristics of the recovered material. Rubber prepared for use in road surfacing has different requirements to that intended for a moulded part or a road mix.
Paving, sports surfaces and asphalt mixes
Some of its best-known applications include safety surfacing, sports surfaces, paving slabs and spring-base surfacing. Its ability to absorb shocks and vibrations works well in these types of products. It can also be incorporated into certain asphalt mixes used on roads and other surfaces.
Technical components, insulation and furniture
Reclaimed rubber can also be used to make bumpers, protective covers, moulded parts, insulating panels or street furniture. Its flexibility and strength continue to be useful in applications that require it to absorb impacts, dampen vibrations or withstand frequent use without easily losing its properties.
Steel returns to the metallurgical cycle
A tyre also contains a certain amount of steel which retains its value even after the tyre has reached the end of its useful life. Once recovered and sufficiently cleaned, it can be returned to the steel industry as a raw material.
Its fate is usually linked to scrap yards and steelworks, which may process it alongside other scrap metal to produce steel once again. From there, it is used in the manufacture of new products for the construction, automotive and industrial sectors, amongst many others.
The value of this fraction lies precisely in the fact that the steel can go through this cycle several times. Keeping a fraction with few traces of other materials makes it much easier to reuse it later. The tyre is thus no longer seen merely as rubber waste. It also contains a ferrous raw material that can be returned to the metal recycling process and remain within the production chain.
A tyre, a cable and a technical component each present different challenges. Sometimes steel needs to be extracted, at other times copper needs to be recovered, and on other occasions layers or reinforcements need to be separated. This difference affects the size reduction process and the subsequent stages.
The textile sector: a more complex challenge
The textile fibres that reinforce the tyre are more difficult to analyse than rubber and steel. They may be made of polyester, polyamide or other materials; furthermore, the composition is not always exactly the same from one tyre to another.
That is one of the reasons why this fraction has fewer established applications than recycled rubber products. To manufacture a new product, a fairly consistent raw material is required, and achieving that consistency is much more difficult when there are different types of fibres or small quantities of other materials.
Part of this fraction can be used for energy recovery, whilst other potential uses are also being investigated, such as in construction materials, new composites and processes that enable the recovery of certain polymers. There is still some way to go in this area. Achieving higher-value uses depends on finding applications capable of utilising the actual characteristics of this recovered fibre.
Why don’t all apps support the same material?
Simply stating that a product contains rubber from recycled tyres does not tell the whole story. Every project requires specific characteristics, and a material that works well in a road surface may not be suitable for manufacturing a technical component.
Several factors influence the applications of recycled rubber:
- Particle size: a fine powder is not used in the same way as larger granules.
- Level of impurities: some applications tolerate small traces of other materials, whilst others require a much cleaner fraction.
- Elasticity and strength: the rubber must retain properties suitable for its intended use.
- Consistency of the material: if parts are to be manufactured, it is important that the raw material behaves in a similar way from one batch to the next.
Consequently, the more stringent the requirements for the end product, the more closely the characteristics of the recovered material must be controlled. This difference also affects its value and the likelihood of it finding a new application.
From the NFU to new resources: the value lies in making a clear distinction
An end-of-life tyre (ELT) contains various materials that can still be reused. Each component has a different end-use:
- Rubber: can be reused in road surfacing, components, insulation or asphalt mixes.
Steel: returns to the metallurgical cycle as a raw material.
- Textile fraction: it has fewer outlets, although it can be used for recovery or for new applications currently under development.
For this reason, the uses of recycled rubber and other materials depend heavily on the quality with which each fraction is recovered. The cleaner and more clearly defined it is, the more options there will be for its subsequent use.
This efficient use of materials is also the starting point for Silmisa’s work in designing machinery and solutions for recycling plants seeking to recover the resources contained in their waste more effectively.