Hot Mix Asphalt Technology - January/February 2008 - (Page 11)

Denmark and Norway in 2002. The technologies viewed included Asphamin (synthetic zeolite), Sasobit and WAM Foam. At one production facility we observed a side-by-side comparison of warm mix and hot mix. With the warm mix, there were no fumes, no odors, lower energy consumption, and lower CO2 production, and no discernable differences in mix workability compared to hot mix. The potential benefits of warm mix for the U.S. industry were self evident. NAPA’s leadership decided to work with its partners to encourage and evaluate various warm-mix technologies in a U.S. setting. Also, AASHTO, working with FHWA and industry, conducted a warmmix scan tour of France, Germany, and Norway in 2007. The general consensus was that WMA should provide equal or better performance than HMA. Industry and its partners have moved from curiosity and some wellbased skepticism to a genuine interest in this technology. Warm-mix asphalt is the hot topic at just about every state and national asphalt meeting. Ongoing progress has been reported through NAPA workshops, World of Asphalt, and demonstration events. Warm-mix asphalt technology has the potential for being one of the most important breakthroughs for the asphalt industry in over 50 years. Vision The current market environment includes high energy prices, pressures on highway funding, the likelihood of more restrictive environmental regulations, continued pressure on plant zoning/permitting, and a surge in mainstream environmentalism. The planets are aligned for warmmix asphalt to help with these issues because it can: • Permit higher RAP content without excessive emissions or poor workability. Also, less aging of the virgin binder in warm-mix production may allow higher RAP percentages without changing the virgin binder grade. • Provide energy savings of 10-20 percent. • Reduce the carbon footprint of asphalt pavement production Current status Considerable progress has been made in the five and a half years since the initial study tour. The various technology vendors have been very responsive. They have invested in research and have worked with contractors and DOTs to conduct numerous field trials. Several new technologies have evolved, and some hot-mix producers have developed their own in-house technologies. To date NCAT’s research on mix characteristics using several of the technologies has been favorable. Also, experience on field projects has been positive with regard to construction and short-term performance. A WarmMix Asphalt Technical Working Group was formed by FHWA and NAPA in 2005. The group’s charge is to foster proper implementation through the evaluation and validation of warm-mix technologies and to guide development of a generic performance specification. There has been considerable interest by the state DOTs, and they have supported two major national research projects on warm-mix design, performance, and environmental characterization through the National Cooperative Highway Research Program (NCHRP). This research should be completed within the next two to three years. and construction by reducing greenhouse gas emissions. • Minimize or eliminate fumes, emissions, and odors. • Improve working conditions at the plant and paving site. In addition, there have been several operational benefits from field projects that are yet to be fully evaluated or understood. These include more time for compaction, the ability to store and haul the mix for a longer time, and the opportunity for extending the paving season. The environmental benefits are a given. The challenge is clear. We need to continue to evaluate warm mix and be able to demonstrate through field observation and research that warm mix has the same coating, the same workability, the same air voids and the same performance as hot mix. In essence, warm mix must equal hot mix. We must not lose any of the performance benefits we’ve achieved with Superpave, SMA, and opengraded friction courses. In the short term, it is likely that contractors will start using this technology in their private sector/ commercial work. Acceptance by state DOTs, cities, and counties may take a little longer, but public agencies are showing great interest in technologies that are “green” or use sustainable construction practices and materials. For example, more than 600 city mayors have agreed to meet the Kyoto targets and are looking at ways to reduce greenhouse gas emissions. In addition, climate-change legislation has been introduced in at least 17 states. They will hear about warm mix and will be eager to try it. Since the 2002 NAPA Study Tour, the proactive work that has been done with all of our partners has positioned the industry for long-term strength and success. The industry now has a golden opportunity to keep several steps ahead in an ever changing and difficult operating environment. Let’s continue to lead and put our best foot forward. HMAT Hot Mix Asphalt Technology – JANUARY/FEBRUARY 2008 • 11

Table of Contents Feed for the Digital Edition of Hot Mix Asphalt Technology - January/February 2008

Hot Mix Asphalt Technology - January/February 2008 Contents Chairman's Commentary President's Perspective A Conversation with the New NCAT Director NCAT Test Track: Real-Time Testing for Real-World Results Warm Mix: The Lights are Green Illinois Tollway Tests RAP in Fast Forwarded Research Big Creek Teams with TxDOT to Pave Using Innovative Asphalt Mix Diamond Achievement Commendation Issues a Call for Quality Calendar of Events CONEXPO-CON/AGG Product Review Index of Advertisers Advertisers.com

Hot Mix Asphalt Technology - January/February 2008

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