Hot Mix Asphalt Technology - January/February 2008 - (Page 25)

Warm Mix: The Lights are Green continued Warm Mix Asphalt State of the Practice Timeline 1999-2001 • Initial reports of warmmix technologies at Eurasphalt/Eurobitume Congress, German Bitumen Forum, Conference on Asphalt Pavements for Southern Africa, and elsewhere. 2002 • European scan tour to Denmark, Germany, and Norway for NAPA leaders to examine warm-mix asphalt (WMA) technologies including Aspha-min, WAM Foam, and Sasobit. This includes meetings with German Bitumen Forum representatives regarding activities of the Temperature Reduction Working Group. 2003 • WMA featured at NAPA’s Annual Convention. • NCAT research on WMA processes Aspha-min (crystalline zeolite) and Sasobit (a FischerTropsch wax) begins. Research sponsored by NAPA, FHWA, Eurovia (Aspha-min), and Sasol (Sasobit). 2004 • MeadWestvaco introduces Evotherm DAT (chemical additive). Supports NCAT research. • WMA demonstration featured at World of Asphalt. • First field trials constructed in Florida and North Carolina. 2005 • NAPA-FHWA WarmMix Asphalt Technical Working Group (TWG) formed. Primary focus is proper implementation through data gathering and analysis to develop a generic method of specification. • Research problem statement submitted for AASHTO consideration. • Field trials in Florida, Indiana, Maryland, New Hampshire, Ohio, and Texas; and in Ontario and Quebec, Canada. • NCAT reports published on Sasobit and Asphamin. 2006 • Asphalt Pavement Conference at World of • Asphalt features a halfday session on WMA. TWG publishes guidelines on performance and environmental testing. Based on research problem statement submitted in 2005, AASHTO gives top priority to funding WMA research. TWG submits two more research problem statements for AASHTO consideration. Field trials in California (asphalt rubber mix), Michigan, Missouri (new application to avoid temperature-caused bumps in road), New York (new process – Low Energy Asphalt), Ohio (open house with 225 people), South Carolina, Texas, Virginia, and Wisconsin (open house). Missouri contractor converts production paving jobs to warm mix based on success of trial. NCAT report published on Evotherm. Numerous NAPA presentations requested. 2007 • AASHTO-FHWA Scan Tour conducted. Visits included France, Germany, and Norway. • TRB session on WMA. • Astec Industries introduces its foamed asphalt technology. • MeadWestvaco introduces Dispersed Asphalt Technology (DAT) introduction system for Evotherm. • Another zeolite product, Advera WMA, introduced by PQ Corporation. • City street demo in San Antonio for APWA’s Annual Meeting. • 30,000 tons of several technologies placed near Yellowstone in August. • Numerous field trials conducted in California, Illinois, New Jersey, New York, North Carolina, Ohio, South Carolina, Tennessee, Texas, Virginia, Wisconsin, Wyoming, and other states; and in Ontario and Vancouver, Canada. • • • • • • reduce the temperatures quite as much. We have to be careful not to oversell the technologies. You’re not going to take a stiff mix and improve density and drop the mix temperature by 100 degrees. All those things aren’t going to happen.” Test results so far, though, indicate that warm mix will perform well. Crews placed two sections of Evotherm warm mix and a control on the NCAT Test Track in fall 2005, said Andrea Kvasnak, Ph.D., a research engineer at NCAT. After a half-million equivalent single axle loads (ESALs), the average rut depth for the Evotherm sections was 0.9 mm; for the Evotherm plus-3 percent-latex section the average rut depth was also 0.9 mm; and the hotmix control section had an average rut depth of 1.1 mm. The rut depths were determined via a wire-line. Questions have been raised about the tensile strength ratio (TSR) of warm mix. If the TSR ratings fall too low, that would indicate a tendency for moisture damage to be occurring. However, Brian Prowell, Ph.D., a researcher for Advanced Materials Services, said more than 20 cores taken from four locations show no indications of water damage after durations ranging from four months to a year after construction. The four locations were: an Aspha-min stretch in Orlando, Fla.; an Evotherm section at the NCAT test track; Hall Street in St. Louis, where Aspha-min, Sasobit and Evotherm were placed; Hot Mix Asphalt Technology – JANUARY/FEBRUARY 2008 • 25

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

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.