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.

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

Repurposing waste plastics into cleaner asphalt pavement materials: A critical literature review

Effect of mixing sequence on asphalt mixtures containing waste tire rubber and warm mix surfactants

In order to assess sustainability of products and processes, different methodologies have been developed and used in the last years. In the road pavement construction area, most methodologies used for Life Cycle Assessment (LCA) are essentially focused in the construction phase. The present paper analyses the importance of the use phase of a road in the LCA of different paving alternatives, namely by evaluating energy consumption and gaseous emissions throughout the road pavement’s life. Therefore, a new LCA methodology for road pavements was developed, and the results of its application to a case study involving the construction of alternative pavement structures are discussed. The study intends to assess the influence of using more sustainable paving construction alternatives (asphalt recycling vs. conventional asphalt mixtures), and/or different surface course materials (which have a higher influence on the rolling resistance and, therefore, affect the performance during the use phase). The LCA results obtained for this case study showed that the reductions in energy consumption and gaseous emissions obtained during the use phase, for pavement alternatives with a lower rolling resistance surface course, are higher than the total amount of energy consumption and gas emissions produced during construction. It is therefore clear that some improvements in the characteristics of the surface course may have an effect over the road use phase that will rapidly balance the initial costs and gas emissions of those interventions. The LCA results obtained also showed that the sustainability of pavement construction may also be improved using recycled asphalt mixtures.

/pdf/the-importance-of-the-use-phase-on-the-lca-of-ynbfigawld.pdf

The importance of the use phase on the LCA of environmentally friendly solutions for asphalt road pavements

Recycled plastic as bitumen modifier: The role of recycled linear low-density polyethylene in the modification of physical, chemical and rheological properties of bitumen

With the increase in road traffic more demands are placed on pavements, and thus the structural and functional performance of road pavements needs to be improved. One method that can greatly improve the quality of the flexible pavements is the addition of polymers to the bitumen or to the asphalt mixtures. Although the modification of bitumen with virgin polymers can improve the properties of asphalt mixtures, the use of recycled plastic may also show a similar result with additional environmental advantages. This work aims to evaluate the possible advantages of modifying the bitumen with different plastic wastes, namely polyethylene (high density HDPE and low density LDPE), ethylene-vinyl acetate (EVA), acrylonitrile-butadiene-styrene (ABS) and crumb rubber, in order to improve the properties of the resulting binders for use in high performance asphalt mixtures. The performance of modified binders with recycled polymers was compared with that of the conventional bitumen and the one of a commercial modified binder (Styrelf). The results of the laboratory tests (basic characterization, dynamic viscosity, resilience and storage stability) will be used in the selection of the best plastic waste materials and production conditions that should be used in the modification of bitumen in order to optimize its behaviour, emphasizing that this study aims to promote the reuse of plastic waste in a more environmental and economic way.

http://www.ijprt.org.tw/reader/pdf.php?id=332

Incorporation of Waste Plastic in Asphalt Binders to Improve Their Performance in the Pavement

https://repositorium.sdum.uminho.pt/bitstream/1822/58930/1/2942-FINAL_PAPER.pdf

Using waste polymers as a reliable alternative for asphalt binder modification – Performance and morphological assessment

The mechanical performance of a typical surface course mixture, modified with two different plastic wastes, both via the wet and dry processes, was evaluated in this study. Water sensitivit...

Asphalt Surface Mixtures with Improved Performance Using Waste Polymers via Dry and Wet Processes

Effect of incorporating different waste materials in bitumen

Every year, millions of tons of plastic waste, with potential to be reused, are wasted in landfills. Based on a literature review and in a local market analysis, cross-linked polyethylene (PEX) waste arose as the material with the greatest potential to be tested for incorporation in asphalt mixtures due to the difficulty in its recycling and the lack of solutions for its reuse. Thus, in the present work, mixtures produced with and without PEX were tested in order to compare their performance, aiming at understanding if this waste could successfully be used as an alternative material for this type of application. Thus, water sensitivity, rutting resistance, stiffness modulus and fatigue cracking resistance tests were carried out on asphalt mixtures with up to 5% PEX. Based on the results obtained, it can be concluded that the incorporation of PEX in asphalt mixtures is a viable solution for paving works, especially when high service temperatures are expected. It also decreases the density of the mixture, which can be attractive to lighten structures. Thus, this technology contributes to give new life to cross-linked polyethylene plastic waste.

https://www.mdpi.com/2076-3417/7/6/603/pdf

Liliana M. B. Costa

Papers

Incorporation of Waste Plastic in Asphalt Binders to Improve Their Performance in the Pavement

Using waste polymers as a reliable alternative for asphalt binder modification – Performance and morphological assessment

Asphalt Surface Mixtures with Improved Performance Using Waste Polymers via Dry and Wet Processes

Effect of incorporating different waste materials in bitumen

A New Life for Cross-Linked Plastic Waste as Aggregates and Binder Modifier for Asphalt Mixtures