Sold-out Test Track Cycle Focuses on Reducing Life-cycle Cost, Innovative Materials
An unprecedented amount of real-world, accelerated pavement testing will take place during the current fifth cycle of NCAT's Pavement Test Track (2012-2015). The cycle sold out by early summer, with a total of 45 sections being sponsored by highway agencies and private industries.
Twenty-five of those sections remained in place from the fourth (2009) research cycle for further trafficking and evaluation, and 20 sections have been newly constructed. A track "sell-out" technically occurs when the 26 tangent sections — those located on the straightaways—are sponsored, so that target was well exceeded for the fifth cycle.
"By the time track reconstruction began this summer, the tangents were sold out and sections were being located in the curves wherever practical," explains Test Track Manager Buzz Powell.
Economical Mixes for Low-Volume Roads
In recent years, transportation funding has dwindled, while the cost of maintaining roads has risen, creating a challenging situation for engineers responsible for keeping the nation's highway system in acceptable condition. The asphalt industry is responding to the challenge, providing ways to reduce construction and preservation costs as well as improving material performance to reduce life-cycle cost.
Selecting Virgin Binders for RAP Mixes Based on Regional RAP Binder Properties
Contractors and agencies are gaining confidence with the use of higher RAP contents. Field performance studies, including studies that compared long-term performance of overlays with virgin and 30 percent RAP mixes as well as test sections on the NCAT Pavement Test Track with up to 50 percent RAP, have shown that higher RAP content mixes can perform well if they meet standard mix design and quality assurance criteria.
Market Analysis Identifies Strengths, Needs of WMA
The National Center for Asphalt Technology (NCAT) recently conducted a nationwide market analysis of the use of warm-mix asphalt (WMA) to assess the current state of practice. This analysis was conducted mainly through a series of surveys NCAT disseminated to four stakeholder groups: state departments of transportation, asphalt paving associations (APAs), contractors, and WMA suppliers.
NCAT Offers Recommendations on Characterizing RAS
The use of recycled asphalt shingles (RAS) in asphalt mixes is on the rise. A recent survey conducted by the National Asphalt Pavement Association (NAPA) showed that RAS use increased by more than 50 percent from 2009 to 2010. Nationwide, 1.1 million tons of RAS were recycled into asphalt mixes in 2010, conserving more than 200,000 tons of virgin asphalt binder.
Asphalt Forum
NCAT invites your comments and questions, which may be submitted to Karen Hunley at karen.hunley@auburn.edu.
Mark Woods, Tennessee DOT
When selecting candidates for re-surfacing projects, what does your state find the most useful (pavement management data, indices, tests, procedures, etc.) for a healthy resurfacing program?
Specification Corner
Missouri
Missouri is currently looking at over-compaction on the roadway of 75-gyration stone-matrix asphalt (SMA) mixtures. Discussions with industry will focus on specification changes to limit compactive effort or possibly moving back to 100-gyration mixtures.