VAASPHALT.ORG 11 TOWARDS SUSTAINABLE PAVING Researchers and engineers started looking at asphalt mixtures as a potentially viable “home” to incorporate some of the recycled plastic waste commodity. There is a growing body of literature on the use of recycled plastic waste in asphalt, but much of the documented efforts lack a clear experimental plan and suffer from the use of dated test methods. Moreover, it is still unclear if producing and paving recycled plastic modified (RPM) asphalt mixtures would require any changes to typical paving practices, especially to those in Virginia. Finally, future research was recommended with a particular focus on sourcing and methods of incorporating recycled plastics, material characterization of laboratory and field produced asphalt mixtures modified with recycled plastic waste, plant operations, health and safety, and mainly construction of field demonstration projects and associated short- and long-term performance. What’s in It for Virginia? The initiative of incorporating recycled plastic waste into asphalt mixtures has been on the agency’s radar for years. This initiative promotes defining a sustainable solution for both improving the performance of asphalt pavements in Virginia and diverting waste plastic from being placed in a landfill or incinerated into a secondary use as a commodity replacement for other raw materials. Seven types of plastics are currently identified with various chemical and physical properties (such as melting points and others). With the existence of multiple plastic types and the major uncertainties due to the variabilities in their properties, such an initiative will help the agency gain a gradual knowledge about the types of recycled plastic waste that may be compatible with the paving material typically used in Virginia (e.g., asphalt binders, aggregates and others) and that are expected to result in longer-lasting pavements. As much as we care about diverting plastics and any other material coming from various waste streams (tire rubber, RAP, glass, etc.), we also care about including these materials in a very responsible manner that would guarantee good performance. continues on page 12 △ With the change in recycling streams over the past few years, the interest in diverting plastics from the waste stream for reuse in asphalt has been a growing topic for highway agencies. Like many other state highway agencies, the Virginia Department of Transportation (VDOT) is extensively working to determine how to best incorporate recycled materials such as recycled asphalt pavement (RAP), recycled crumb rubber, and crushed concrete into their roads. With the change in recycling streams over the past few years, the interest in diverting plastics from the waste stream for reuse in asphalt has been a growing topic for highway agencies. In 2017, plastics accounted for 35.4 million tons of waste in the United States with only 3 million tons (8% of the plastic waste) being recycled, 5.6 million tons (16% of the plastic waste) undergoing combustion, and 26.8 million tons (76% of the plastic waste) being stacked and landfilled. Hence, the current plastic waste challenge became a critical concern.
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