VAA Virginia Asphalt Spring/Summer 2021

VAASPHALT.ORG 17 covered 17.14 miles in each direction, for a total of 68.56 lane miles, with the southern termini occurring at the North Carolina state line. This same pavement section was rehabilitated in 1998 and 1999 with asphalt concrete overlays ranging in thickness from 18.5 inches to 6.5 inches, with the thicker sections being placed on crack and seated jointed concrete pavement (JCP) and the thinner sections being placed on 8 inches of continuously reinforced concrete pavement (CRCP). In an effort to protect the significant investment made in this section of pavement, VDOT began to look at potential pavement preservation treatments in 2007 while the pavement was still in good overall condition. VDOT, in conjunction with the Virginia Transportation Research Council (VTRC), performed a cost analysis comparing typical asphalt overlay alternatives. These alternatives included SM-9.5D, SMA 12.5, and THMACO. Additionally, VDOT evaluated using a latex modified emulsion treatment (i.e., microsurfacing) overlay, which was eventually installed on the adjoining sections for comparison purposes. For THMACO, the per-mile cost included a ¾-inch (85psy) overlay for two lanes (25-feet) and fog sealing for the 10-ft and 3-ft outside and inside shoulders, respectively. The SM 9.5D and SMA 12.5 estimates assume a 1 ½-inch application rate for 36-ft of roadway. One of the many benefits of THMACO is the thin application rate. This is evidenced by the need for wider coverage on the SM-9.5D and SMA 12.5 due to the thicker minimum application rates and the requirement to avoid unsafe edge drops. An alternative would have been a mill and inlay, but that would have required the additional cost for milling. This analysis con- cluded that the THMACO was the best alternative from an initial cost and equivalent uniform annual cost (EUAC) perspective. Based on the EUAC analysis, the THMACO only needed five years of service life to hit the breakeven point. At ten years, the THMACO system approached half the EUAC of the other alternatives. The final 2008 pavement preservation project generally consisted of asphalt patching, crack sealing, applying THMACO, fog sealing the shoulders, and replacing associated traffic engineering items at an awarded contract value of $5,336,453.45. Today So how has it performed? Over 12 years later, and the THMACO is still in service and performing very well. From VDOT’s Pavement Management System, the Critical Condition Index (CCI), as measured in 2020, ranges from 59 to 95, with an average rating of 84. VDOT categorizes pavements with a CCI of 90 and above as I-95 THMACO March 2009 THMACO EXCEEDS EXPECTATIONS While real estate is all about “location, location, location,” pavement preservation is all about “timing, timing, timing” with the proper application. continues on page 18 △