VAA Virginia Asphalt Fall/Winter 2021

24 FALL/WINTER 2021 David T. Lee, PE, Vice President, Virginia Asphalt Association APICTURE OF SUSTAINABILITY Virginia Wins 2020 APA Perpetual Pavement Award Each year the Asphalt Pave- ment Alliance (APA) recognizes state agencies and owners of pavements that had the foresight to build according to perpetual pavement principles. Since 2001, the APA’s Perpet- ual Pavement Award program has recognized 156 long-life pavements in 31 U.S. states and one Canadian province. The winning pavements range in age from 35 years to 91 years, and the pavements average 46.37 years old at the time of rec- ognition. Roads are at least 35 years old when honored and had never experienced a structural failure. Also, a road could not have had more than 4 inches of new material added over the previous 35 years, and it could not have been resurfaced more frequently than once every 13 years. As stated by APA, even though the Per- petual Pavement concept was not articu- lated until 2000, many pavement owners have recognized the benefits of building long-lasting pavements. This is certainly true for much of Interstate 81 in Virginia. Many of the original pavement designers and constructors recognized the need to have robust pavement designs, built from the subgrade up, as critical to a long-lasting pavement. For example, Arthur Barnhart, retired Virginia Department of Transporta- tion district materials engineer, was present during much of the construction of I-81 in the SalemDistrict. He states, "We recog- nized much of the subgrade through the area was extremely weak. As such, we knew something needed to be done to ensure a long-lasting pavement. We were fortunate that many of the roadway cuts were rock and, as such, utilized this material to build a strong subbase." The award winner for 2020 is a pavement section located on southbound I-81 in Roanoke County fromMile Point 133.63 to 136.14. It was opened to traffic in 1964 and currently carries approximately 23,000 directional ADT, 22% of that being tractor- trailers and a total loading to date of nearly 100 million ESALs. As already noted, this area of the Salem District is known for weak clayey, silty subgrade soils. Furthermore, local weather conditions average 41 inches of rainfall and 20 inches of snowfall each year, in addition to many freeze-thaw cycles. Despite the poor subgrade and weather con- ditions, this section of I-81 has withstood over 56 years of heavy truck loading with minimal maintenance. Maintenance averaged 18.7 years between treatments, with the most prolonged period being 30 years between mainte- nance activities. The grade was increased approximately 1.8 inches over the roadway’s lifespan, including a 1.4 inch Surface Mix Asphalt overlay (1994) and a 0.375 inch thick Latex-Modified Slurry Seal (2020). There was also a mill-and-replace of 1.5 inch SMA Surface Mix Asphalt in 2011. Looking at the performance of this roadway section, one can see the factors that played a role in its success. First, crushing and pugmill operations were primarily on-site for much of the construction of I-81 in the area, making these materials readily available. Travis Higgs, PE, present district materials engineer and pavement designer for many of the new continues on page 26 △ Construction of I81 in Salem District early to mid 1960s.