Asphalt Pavement Magazine - March/April 2015 - (Page 20)

Successful Pavement Preservation with THIN ASPHALT CONCRETE OVERLAYS Thinlay tips from the Transportation Research Board report NCHRP Synthesis 464: Thin Asphalt Concrete Overlays By Donald Watson T hin asphalt overlays, increasingly referred to as Thinlays™, are extremely useful as a tool for both routine maintenance and pavement preservation. One factor that makes thin overlays so appealing is they are generally more economical than thicker dense-graded layers, allowing pavement managers to overlay more lane miles with the same tonnage. Thin overlays often have lower life-cycle costs than other pavement preservation treatments, as well. In numerous cases, placement of surface courses less than 1.5 inches (38 mm) thick have been performed routinely, even on high traffic volume and heavy truck routes such as interstates. These thin overlays are an accepted practice and offer numerous advantages (Newcomb, 2009): * Provide long service life when placed on structurally sound pavements; * Provide a good riding surface; * Reduce noise at the tire-pavement interface when fine graded mixtures are used; * Maintain grade and slope geometry with little environmental impact; * Are recyclable; * Are easily maintained. The degree to which thin asphalt overlays are successful depends in large part on the project selection and the amount of distress in the existing pavement. Pavements that are failing, or have already failed, cannot be successfully treated with a thin overlay alone; they must be repaired so that a stable foundation is provided before the thin overlay is placed. Agencies surveyed for NCHRP Synthesis Report 464 reported the service life of thin overlays is generally between 7 and 11 years. The reasons most often continued on page 22 20 * View past issues online at

Table of Contents for the Digital Edition of Asphalt Pavement Magazine - March/April 2015

President’s Perspective Setting the Record Straight on Asphalt Recycling
Industry News TCC Study Finds Transportation Infrastructure Investment Benefits All Sectors of Economy, Silent Auction to Benefit NAPA Care, NAPA Launches Diamond Terminal Commendation, 2015 AASHTO & APTA Bottom Line Report, 2015 Quality in Construction Awards Program Opens for Nominations April 1
Successful Pavement Preservation with Thin Asphalt Concrete Overlays Excerpts from NCHRP Synthesis 464: Thin Asphalt Concrete Overlays
Improving Life-cycle Performance with Pavement Interlayers The right pavement interlayer can mitigate distress and promote long-term pavement performance
NCAT Pavement Preservation Experiment Set to Expand in 2015 Lee Road 159 offers valuable pavement preservation lessons to build on
A Smooth, Rehabilitated Ride in Georgia GDOT’s formula for high quality pavement preservation
Industry Events
Index of Advertisers/

Asphalt Pavement Magazine - March/April 2015