VAA Virginia Asphalt Fall/Winter 2021

28 FALL/WINTER 2021 VTRC PROGRAM OVERVIEW Fall 2021 Kevin McGhee, PE, Associate Director of Research-Pavements, Virginia Transportation Research Council Introduction: A Less “Visible” BMD Presence Since the 2018 construction season, sup- port for Virginia’s Balanced Mix Design (BMD) field trials has been the most visible element of the Virginia Trans- portation Research Council’s research program. In 2021 that support assumed a more secondary role, primarily limited to cataloging key characteristics from a series of BMD pilot projects awarded as part of the annual resurfacing schedules. This less intense BMD role allowed us to explore other material trials with partners from the Virginia Department of Transporta- tion’s T’s districts and our more progres- sive contractors. The advanced material trials from 2021 were of interest for a cou- ple of reasons. First, they offered alterna- tives for achieving particular performance qualities and were thus indirectly relevant to our aspirations for BMD. Second, each trial mixture incorporated something that would typically be considered a waste material and, therefore, potential con- tributors to a more sustainable paving program. Hybrid Rubber Modified Asphalt The first field trials of the summer were conducted in the NOVA District in part- nership with Virginia Paving Company and Superior Paving Corp. They were designed to explore the prospects of hybrid rubber modified asphalt (HRMA). The HRMA mixes used a binder package that included 75% ground-tire-rubber (GTR), 20% styrene-butadiene-styrene (SBS) and 5% rejuvenating additive. Not only does HRMA represent another method for consuming a waste material, GTR, but this application is also a potential alternative for more conventional asphalt modifi- ers to improve resistance to cracking and deformation under heaving loads. Led by Jhony Habbouche and Hari Nair, our research team documented the constructa- bility of the modified mixtures and will be following up with laboratory performance testing and an evaluation of initial field performance. Recycled Plastic Modified Asphalt Jhony and the Research Council’s field support team ventured south for the second series of trials. In this case, our research- ers worked closely with Richmond District Materials and Colony Construction, Inc. to develop a field experiment that would help evaluate methods for modifying asphalt using recycled plastics. The entire experiment, which happened over several nights and a couple of weeks, was designed to benchmark recycled plastic modified asphalts (RPMA) against VDOT’s con- vention D and E mixes. Plastic 1 (Figure 2a) was a complex arrangement of poly- ethylene(PE)-based polymers, and Plastic 2 (Figure 2b) featured the use of polyeth- ylene terephthalate (PET)-based amor- phous polymers. The modified designs were intended to both extend and enhance the base binder. Original sources for these plastics include things like water and soda bottles, food packaging and containers. Similar to the HRMA trial in NOVA, researchers were there to document pro- duce-ability, constructability and initial field performance and collect samples for follow-up testing in the laboratory. The RPMA study will also include an attempt