Automobile tires are made to take a lot of abuse for a long time, so breaking them down for recycling has always been quite a challenge. Spanish scientists are developing a solution to that problem, with a modular tire that has a removable silicone tread.
Ordinarily, when a tire reaches the end of its lifespan, it's taken to a tire recycling facility where it gets shredded.
The resulting rubber "crumbs" are commonly utilized in materials such as playground surfaces and running tracks, or they may be burned as fuel in industrial applications. Other more unique/experimental uses include concrete- and diesel-boosting additives, ingredients for battery anodes and aerogels, and even stuffing for cow mattresses.
In all of these cases, however, separating the steel belt plies and bead cores from the rubber treads and sidewalls is a time- and labor-intensive process. As a result, sometimes tires don't get recycled, and are simply dumped in landfills.
That's where the Universidad Carlos III de Madrid's Ecotire project comes in. It's intended not just to make tires easier to recycle, but also to reduce the amount of the tire that has to be recycled at any one time.
At the heart of the project is a prototype tire in which the tread can be mechanically removed from the sidewalls and casing when it wears out. That tread, which makes up 20% of the weight of the entire tire, is then considerably easier to recycle than the whole thing, as it's essentially just a silicone ring.
The scientists chose silicone, as their research reportedly indicates that it "exhibits approximately ten times less deterioration" as the rubbers used in regular tires, plus it offers greater stability. It could also accommodate electronic sensors, for enabling "smart" tires at some point in the future.
As a side benefit, because only the tread is in contact with the road, the rest of the tire could be made of non-traditional polymers that don't degrade into tiny particles under force of friction. As things currently stand, the rubber particles which are continuously shed by conventional tires are one of the main sources of microplastics pollution.
And yes, when the time comes, the whole Ecotire can be completely recycled.
The prototype has already been evaluated on a rolling test rig, in which variables such as load, radius, slip angle, slip ratio, and inflation pressure were controlled. Road tests with an industry partner may soon follow.
"The behavior of our tire is already similar enough to that of conventional tires that we are very close to transferring it to the industry alongside companies in the sector, although there is still a long road ahead before it reaches society," says the lead scientist, Daniel García-Pozuelo.
A paper on the research was recently published in the journal Applied Sciences.
Source: Universidad Carlos III de Madrid
