14 SPRING/SUMMER 2022 TOWARDS SUSTAINABLE PAVING the feasibility of using these tests to evaluate the “true” performance of RPM mixtures, promising preliminary performance of RPM mixtures were observed, making them qualify to act as “D premium mixtures.” Environmental Aspect of the Initiative In addition to evaluating the performance properties of the produced RPM paving materials, there is a major interest in better understanding the potential environmental impacts associated with the use of recycled plastics in asphalt mixtures. For example, per night, this trial helped save the equivalent weight of approximately 635,000 single-use plastic bags going to landfills. This was accompanied by an offset of approximately 10,770 kg of CO2. Although these numbers might seem low because only one trial was done, an increase in using such alternatives can help reduce fossil fuel usage, leading to a reduction in carbon footprint and helping to foster a circular economy. On the other side, along with an increased interest in the reuse of waste plastics, a growing concern has been raised regarding the topic of microplastics in the environment. Lewis N. Lloyd, research scientist at VTRC with expertise in waste management and beneficial reuse of waste material, is handling the environmental aspect of this initiative. His efforts will attempt to detect and quantify the presence of microplastics in material generated from pavement wear that could potentially be introduced into the environment through stormwater runoff. This portion of the research is still in its early stage, and no firm or clear conclusions have been derived yet. Ongoing and Future Work We learned many lessons from this trial about practices covering the mix design and production stages, but there is still more to figure out. Multiple field trials are being planned for the upcoming 2022 paving seasons. These trials are expected to feature similar and new types of plastic waste. Moreover, the research team will continue evaluating the RPM and control mixtures in the laboratory with a major focus on critical long-term aging and in the field through non-destructive testing. One major item on the team’s radar in 2022 is about evaluating the feasibility and the process of recycling asphalt mixtures already containing recycled plastic. This will highlight the impact of such processes on the properties and production of such mixtures, and the potential generation of hazardous emissions on the environment. Acknowledgements This important and extensive effort could not be accomplished without the contribution and hard work of several parties. Appreciation is extended to Thomas Schinkel, the material engineer for VDOT’s Richmond District, for allowing this trial to take place in his district. Support from personnel at VDOT’s Richmond district and VDOT’s Materials Division is greatly appreciated. Sincere appreciation is expressed to Travis Cable, Vice president of quality control, and the team at Colony Construction Inc. In addition, the assistance and support provided by the plastic suppliers MacRebur and Kao Chemicals and the supplier of fiber feeders/machines, Hi-Tech Asphalt Solutions, are greatly appreciated. Finally, appreciation is extended to VTRC leadership and staff for their continuous support of innovative efforts. △ continued from page 13 On the other side, along with an increased interest in the reuse of waste plastics, a growing concern has been raised regarding the topic of microplastics in the environment. This portion of the research is still in its early stage, and no firm or clear conclusions have been derived yet.
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