Hot Mix Asphalt Technology - May/June 2011 - (Page 31)

States Stride Ahead Some states adopt permissive specs; others proceed with caution By Daniel C. Brown With Warm Mix S tate transportation departments across the nation are implementing new specifications that permit the use of warm-mix asphalt under most conditions. In a number of states, such as Texas, Alabama, and Virginia, warm mix has moved beyond the trial stage and is used routinely. Other states, such as Colorado and California, are proceeding more slowly toward a standard warm-mix specification. “In spring 2010, New York State implemented a special warmmix specification under FHWA’s experimental features program,” says Bruce Barkevich, vice president of the New York Construction Materials Association. “It allows us to place a specification more quickly but it has some data collection and research requirements.” California (Caltrans) expects to develop warm-mix specifications by May 31, 2011. Then, by July 31, Caltrans wants to have warm-mix guidelines completed. The state’s first warm-mix project was paved in 2006, and at least 17 projects totaling about 72,000 tons have been placed through October 2010. Wherever warm mix is used, it is performing well and playing to rave reviews. Test sections at the 1.7-mile oval operated in Alabama by the National Center for Asphalt Technology (NCAT) have held up very well. “So far, warmmix performances have been all positive,” says Buzz Powell, PhD, P.E., an assistant NCAT director and test track manager. Powell cites four 200-foot-long examples from the test track: S10, S11, N11 and E10. Placed in 2005, section E10 has survived approximately 16 million ESALs (equivalent single axle loadings). Warm-mix section N11 has 50 percent reclaimed asphalt pavement (RAP) and has shown less than 5 millimeters of rutting after 4 million ESALs. It has an International Roughness Index of less than 50 inches/mile and no cracking. “We have seen just a tad more deformation in the warm-mix sections because the liquid binder is Lafarge West paved this warm mix in Larimer County, Colorado. Hot Mix Asphalt Technology – MAY/JUNE 2011 • 31

Table of Contents for the Digital Edition of Hot Mix Asphalt Technology - May/June 2011

Hot Mix Asphalt Technology - May/June 2011
Chairman’s Commentary: Who Knew Asphalt Could Be So Green?
Industry News
Warm-Mix Asphalt: Best Practices
States Stride Ahead With Warm Mix
Roads to Rubble: De-Paving a Half-Century of Progress
NCAT Explains the AMP Tester
Tools for the Trade
Calendar of Events
Index of Advertisers/

Hot Mix Asphalt Technology - May/June 2011