Developed countries in terms of the industry have 9 kg of wasted tires generated per person every year.
For instance, in America, there are an estimated amount of 2 to 3 billion of illegal restored scrap tires. In the mean, while the same issue exists in European union but on a larger scale and with 5.7 million tones.
In Hungary, there are about 2.7 active cars, and they generate approximately 40,000
Tones of wasted tires, yearly.
This massive number of scraps brings about lots of business possibilities.
Blending these scraps with bitumen and create high-quality material for paving applications is one of the best uses for them.
Since utilizing the crumb rubber in bitumen paving, there have been two essential processes for blending the two: dry and wet.
First, the DRY; in this method, they directly add the crumb rubber particles when bitumen and aggregate are mixing.
Second the WET; it is a general type that includes any kinds of methods in which they add the particles of the rubber to the bitumen before they add aggregate to the bitumen.
The process goes like this:
In this method, the particles of plastic react with bitumen at an elevated temperature, the duration of applying temperature differs, and to get the different required properties for different engineering proposes.
During this process what happens is that both components swell together and also the rubber experiences some dissolution, but it is mostly absorption of oils from inside bitumen in the rubber matrix
As next phase in this process, some activation method of crumb rubber surface needs to be applied to produce rubber bitumen (which has already been modified chemically), or they can as well use special additives for improving compatibility.
The reason for using these binders is that they are more stable and also because of crumb rubber is somehow a modification agent in the disperse system of rubber bitumen. That explains the reason why it is possible to expect almost the same reaction to that of polymer modified bitumen.
After the first experiments, it was immediately proved that the production of rubber bitumen has a way more significant than just the utilization of tire scraps. The other benefit to it is that by adding rubber into bitumen in pavements their quality and durability will enhance in comparison to roads built with standard bitumen binders.
The advantages to follow are emphasized because of the rubber bitumen pavements: longer life span, cheap life cycle, more flexibility with different temperature ranges, susceptibility in improved temperature, traffic noise reduction of traffic noise, more resistance against deformation and improved resistance toward skid.
Sometimes rubber bitumen production that has suitable elements of the wet process can reach batter standards and properties,
in some conditions like cold cracking than polymer-modified bitumen.
The USA is the biggest consumer of rubber bitumen,
Because rubber modified binder is produced in situ, close to asphalt mixing plant by road construction.
Due to extreme settling tendency of undissolved rubber particles, maybe sometimes transportation becomes a huge issue. Normally
rubber bitumen binder has to be blended with
aggregates in less than a few hours because of its ability
Of phase separation.
High viscosity and
modulus of rubber bitumen cause increased
permanent resistance against deformation even though
the usefulness of this binder causes difficulties in
asphalt mixing plants and while compaction of asphalt.