RAP-ELT

Project Summary

Recycled rubber can improve the performance of an asphalt mix at high temperatures. Improved performance is also observed throughout the temperature range that asphalt pavement is exposed to over time.

The modification of the asphalt mixture by rubber crumb or powder from the mechanical granulation of End of Life Tyres, has the following advantages:
Longer life of the asphalt pavement
Higher resistance to high temperatures (reduction of wheel bolts)
Higher resistance to low temperatures (crack reduction)
Reduced noise from vehicle traffic
Reduction of “spraying” from vehicle traffic on wet roads.

The existing practice concerns the addition of a rubber crumb in two possible ways, the so-called dry and wet methods. With the wet method, the tire crumb/powder functions as a bitumen modifier while the dry method uses tire crumb to replace the inert material. The substitution rates are usually for the dry method of 1% to 3% and for the wet method from 5% to 13%.

However, up to now, according to the literature, applications do not appear to have focused at two points in the use of a tire tread in road construction:

1) The ability to mix a recycled bitumen reclaimed asphalt pavement (RAP) and primary aggregates and asphalt for the production of asphalt mixtures in order to increase the permissible recycling rate (RAP) in the final product, as well as
2) The substitution of coarse aggregate in the mixture of asphaltic aggregates in order to increase the quality of the asphalt mixture and increase its lifetime.

The project will investigate

i) The percentage of tire crumb use for asphalt modification, by substituting other modifiers
ii) The possibility of increasing RAP’s participation in the production of asphalt mixtures by virtue of the inclusion of the tire crumb.
iii) Coarse-grain substitution rates in bituminous mixtures by maintaining and / or increasing their quality characteristics. The possibility of using rubber crumb to modify the bulk bitumen used in the production of bituminous mixtures.

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