Crumb Rubber From End‐of‐Life Tires to Reduce the Environmental Impact and Material Intensity of Road Pavements: Fid-Bau Portal

Crumb Rubber From End‐of‐Life Tires to Reduce the Environmental Impact and Material Intensity of Road Pavements

Farina, Angela / Anctil, Annick / Emin Kutay, M.

Flexible pavements cover 95% of the roads in the USA and include approximately 400 million tons of asphalt mixtures composed of natural aggregates and asphalt binder. Polymer modifications improve the durability of flexible pavements and are proven to prolong the service life. Crumb rubber (CR) from end‐of‐life tires might substitute the synthetic polymer in the asphalt mixtures, reducing tires disposed of in landfills. In the USA, the recycling of end‐of‐ life tires contributed to lowering landfill disposal from 75% in the 1990s to 17% today. In 2021, in the USA, the use of CR in asphalt mixtures accounted for only 10% of the total CR market. This percentage could be increased by demonstrating the benefit of using end‐of‐life tires in road pavements. In this work, an integrated approach between life cycle assessment and mechanistic‐empirical pavement design was used to evaluate long‐term mechanical performance, environmental impact, and quantity of materials saved over the service life of road pavements. Laboratory‐prepared asphalt mixtures modified with polymer coated rubber (PCR, dry and wet technology) and devulcanized rubber (DVR) were compared to reference blends (control ‐ unmodified, and SBS ‐ modified with synthetic polymer styrene‐ butadiene‐styrene). Global warming potential (GWP), fossil depletion, and cumulative energy demand were quantified for a 1‐mile surface layer over the pavement service life in Michigan. Environmental impacts depended on the long‐term mechanical response of each asphalt mixture because the major contribution of the total environmental impacts was attributed to the number of cycles of reconstruction obtained from the mechanist‐ empirical pavement design. The PCR dry mixture had the lowest environmental impact compared to the other mixtures containing CR. The GWP for the PCR dry layer was 45.7% lower than the carbon footprint of the control layer and 8.0% lower than the SBS layer. Using asphalt mixtures modified with SBS or PCR dry can save up to 58.0% of materials compared to the unmodified control mixture over 50 years. Tires recycling contributes to the circularity of materials by minimizing the use of virgin materials and reducing waste and lowers the environmental impact of road pavements.