VAA Spring/Summer 2020

24 SPRING/SUMMER 2020 SUSTAINABLE... RESILIENT... ASPHALT Each year, a new set of buzzwords or cliches are used in our society and culture. A quick search of the internet lists the most popular words for 2019. Concepts such as “disruptor,” “data mining,” “agile,” and “synergy.” While all are impressive- sounding, what do they mean? For the transportation industry, the common buzzwords of “sustainable” and “resilient” are used, but what do these words mean concerning transportation and specifically pavements? In October 2014, FHWA published TechBrief 1 (2014 TechBrief) which defined a sustainable pavement as: “One that achieves its specific engineering goals, while, on a broader scale, (1) meets basic human needs, (2) uses resources effectively, and (3) preserves/restores surrounding ecosystems.” As the 2014 TechBrief acknowledged, it is an “aspirational goal” and will take time to achieve. Along with sustainable, “resilient” has been used extensively with infrastructure, particularly as the number of natural disasters seems to increase. Whether it was the hurricanes along the Atlantic and Gulf Coasts or earthquakes in Alaska, roads and bridges need to withstand the destruction or be renewed/repaired quickly to allow for the flow of emergency supplies to impacted areas. So, how are asphalt pavements sustainable and resilient? Asphalt – The Sustainable Choice The 2014 TechBrief outlined pavement sustainability in terms of Pavement Life Cycle, Measuring Sustainability, and Impacts. The pavement life cycle is the “cradle to grave” concept, starting with securing the pavement materials, to design, to use, and finally end of life. When the interstate system was established in 1956, new highways were constructed primarily as “green-field” projects. While some sections of interstates utilized existing pavements, most of the mileage was comprised of new pavements from the subgrade up. The cradle for these pave- ments utilized virgin aggregates and virgin asphalt binders. Early interstates did not include recycled asphalt pavements because they either did not exist or were not even considered. Today, the cradle for new pavements contains varying percentages of recycled materials along with virgin aggregates and binder. The role model for sustainable pavement is I-64 between Williamsburg and Hampton. I-64 Segments 2 and 3 are complete reconstruction and widening of pavements built in the 1950s and 1960s. Constructed initially as jointed reinforced concrete pavement, deterioration over time lead to Photo courtesy of Allan Myers I-64 Project Trenton M Clark, P.E., President, Virginia Asphalt Association