Reclaimed Polymers as Asphalt Binder Modifiers for More Sustainable Roads: A Review

Abstract

The use of polymer-modified binders in asphalt mixtures has become more widespread due to their reduced thermal susceptibility and improved rutting and fatigue resistance. Nevertheless, their high cost limits their application, thus making the use of reclaimed polymers (RP) an interesting alternative for both reducing price and extending the service life of pavements. This paper; therefore, presents a comparative review of the recycled polymers most commonly studied as bitumen modifiers: polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), ethyl vinyl acetate (EVA), and ground tire rubber (GTR), in order to facilitate their selection and extend the use of the bitumen. The differences in terms of melting point, mixing conditions, and maximum quantity of added polymer are analyzed. Moreover, their effect on the mechanical behavior of the asphalt binders and their stability with and without the use of additives is presented. According to the literature revision, the performance of the new binder is more influenced by the kind of polymer that was incorporated and the mixing conditions than by the base bitumen that was chosen, although rheological evaluation is needed to fully understand the modification mechanisms of the modified binder. In general terms, plastomers have a stronger effect in terms of increasing the stiffness of the bitumen in comparison with crumb rubber (elastomers), thus providing an improved rutting resistance. The joint use of polyethylene (plastomer) and crumb rubber (elastomer) can be an interesting option for its recycling potential and mechanical performance, although further study is needed to achieve stable bitumen across the entire range of temperatures; additives, such as maleic anhydride (MA), are commonly employed to improve the stability of the binder and enhance its characteristics, but their use could limit the economic benefits of using recycled materials.

Fatigue performance evaluation of bitumen mastics reinforced with polyolefins through a dissipated energy approach

“…Few studies report the fatigue performance of bitumen modified with polyolefins even though these polymers have shown improved resistance to permanent deformation. Examples of the sustainable reuse of waste polyolefins as modifiers for asphalt binders can be found in (15,16). Very often, little or no interest is shown in the polymer properties (3,17,18).…”

End of Life Tires as a Possible Source of Toxic Substances Emission in the Process of Combustion

“…In connection with the above, it seems preferable to reduce and, in the long term, reject the thermal methods of processing ELTs due to the inevitable environmental pollution by toxic products. Therefore, one should expect the development of alternative ELT processing methods based on the use of non-energy resource potential, for example, the use of ELTs as bitumen modifiers [32,33]. Due to the growing traffic, loading and aggravation of axis crumb rubber particles in virgin bitumen for superior adhesive and cohesive performance has become common practice [34].…”

Hybrid Polymerisation: An Exploratory Study of the Chemo-Mechanical and Rheological Properties of Hybrid-Modified Bitumen

“…These two polymer groups enhance the specific properties of the bitumen differently. Plastomer-although many different families of plastomer are available nowadays-typically enhances the stiffness and resistance to permanent deformation against loading, while thermoplastic elastomer provides better fatigue resistance due to its elastic properties [16]. However, the most widely accepted bitumen modifier is the SBS copolymer.…”