It's natural to be dismayed by the thought of your car's worn tires being relegated to a landfill somewhere. Fortunately, more and more such tires are being recycled in a revolutionary new way—as an additive for the asphalt used to create roadways. If you would like to learn more about this process, read on. This article will teach you about how old tires find new life in asphalt.
Processing Old Tires
To make use of the rubber in an old tire, it must first be processed. This involves grinding up the entire tire into coarse crumbs. Then the rubber must be carefully separated from any reinforcing fibers or wires, which would otherwise detract from the homogeneity and effectiveness of the rubber.
Bits of steel wire are removed from the ground tire by use of magnets. Fibers are separated through a process of aspiration—in other words, a stream of air is directed at the ground. This air blows out the relatively lighter fibers. The resulting rubber particles must then be carefully sieved into various size categories. If necessary, further grinding of certain sizes may occur.
The rubber additive derived from old tires goes by two main names: crumb rubber modifier (CRM for short) or ground rubber tire (otherwise referred to as GTR). Both of these simply refer to finely ground rubber derived from tires. Asphalt that has been constructed using CRM or GTR is generally known as rubberized asphalt, but can be further divided into two principal categories: asphalt rubber and terminal blend.
There are two key differences between asphalt rubber and terminal blend. First is the percentage of CRM incorporated. Asphalt rubber generally has between 18 and 22% CRM, whereas terminal blend contains anywhere from 10 to 20% CRM. Second, the CRM used in asphalt rubber tends to be somewhat coarser than that used in terminal blend.
Benefits Of Rubberized Asphalt
All forms of rubberized asphalt offer distinct benefits. These benefits extend well beyond the appeal of recycling otherwise-unusable tires. For one thing, rubberized asphalt is much more durable and resistant to wear than traditional asphalt mixes. The rubber content also helps to dampen the volume of passing traffic, thus allowing for roadways with a less pronounced acoustical impact.
Not only that, but rubberized asphalt helps to manage heat. This has to do with the more porous nature of rubberized asphalt, which allows it to cool down more quickly than traditional asphalt or concrete. This helps to reduce ambient heat levels, especially in high density urban areas where building materials tend to soak up massive amounts of the sun's heat.
For more information, contact local professionals like Construction Asphalt Paving Services Inc.Share