Pavement Preservation

The Federal Highway Administration is estimating 2014’s cumulative highway travel miles at a staggering 1,732.4 billion, up from last year by about 0.6 percent. Ultimately, this means using the roadway is the preferred travel method. While cost of vehicle maintenance may be taken into consideration when purchasing a vehicle or making an extended travel plan, did you consider that poor road conditions negatively impact the health of your vehicle as well? How poorly or well maintained a road surface is can impact the wear and tear and gas mileage of your vehicle, travel time, and even overall wrecks. Pavement preservation techniques can improve the life of a road and ultimately your vehicle. There’s one technique that out performs the others, though: thinlays.
PREMIER ASPHALT OVERLAY
A thinlay is a thin asphalt overlay which sets over and seeps into the cracks of existing pavement to increase structural integrity if the existing pavement is already structurally sound. The pavement below is sometimes, but not always, milled first to alleviate any unevenness in the surface. Thinlay attributes include noise reduction, use of recycled materials, pavement strengthening, smoother ride, and increased roadway safety. The ability of a thinlay to improve a pavement’s structural capacity is what makes it the premier asphalt overlay.
While there are more pavement preservation techniques than just thinlays, the National Asphalt Pavement Association (NAPA) has outlined the benefits of thinlays in a position paper. NAPA also included an instructional demonstration on its website which features the Tenth Street project in downtown Nashville, Tennessee. In the video, Mike Huner, director of technical services for the Tennessee Road Builders Association, talks about engineering the thin overlay mix. He explains that they “select aggregates based on gradation and cleanliness [and] put those aggregates together in a certain blend. We run through a mix design where we select optimum AC (asphalt cement) content.” He says they are able to minimize the fumes coming off the product by mixing it at a cooler temperature, saying the project has a “shade of green.” Huner also says the warm mix process gives the thinlay added compatibility.
Being able to engineer the mix of the thinlay adds to the appeal, as making an environmentally friendly pavement preservative has a significant impact. In a population trying to be more environmentally conscious, it’s important to meet the needs of the clients and communities and still be able to provide a quality product that will preserve and prolong the life of current pavement.
NAPA’S SUPPORT OF THINLAYS
Maximum life at minimum cost and with as little disturbance to the community as possible is the ultimate goal behind pavement preservation. In NAPA’s position paper on thinlays, studies showed that construction wrapped up faster, the impact on the community (drivers) was less, and the ability to engineer specific mixes lead to optimized material use, optimized benefits received, and optimized dollars invested. Then, of course, there is the matter of the pavement structure. Thinlays can not only preserve pavement, they can improve the structure of existing pavement. Thinlays can construct a Perpetual Pavement, only requiring periodic surface maintenance to stay in good condition. NAPA is pushing for federal, state, and local transportation agencies to choose thinlays as the top pavement preservation option. ■
For More Information
For more information on pavement preservation and the work being done by the National Asphalt Pavement Association (NAPA), visit www.asphaltpavement.org.