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Dedicated to
providing knowledge, the Pavement Research Center uses innovative research and sound engineering
principles to improve pavement structures, materials,
and technologies.
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Summer 2009 UCPRC News
Hot-mix asphalt (HMA) is produced at temperatures between 280°F and 320°F. These temperatures ensure that the aggregate is dry, the asphalt binder coats the aggregate, and the HMA mix has a suitable workability. Even higher temperatures are used for HMA mixtures containing polymer-modified asphalt binders and crumb-rubber asphalt binders because of their higher viscosities at higher temperatures. Technology is now available to decrease HMA production temperatures from 30°F to as much as 100°F. These relatively new processes and products, collectively referred to as Warm-Mix Asphalt (WMA), use various physicochemical means to reduce the shear resistance of the HMA at construction temperatures while reportedly maintaining or improving pavement performance. The University of California Pavement Research Center (UCPRC) has recently completed the first phase of a comprehensive investigation into warm-mix asphalt for the California Department of Transportation (Caltrans). This included monitoring the production of HMA and three WMA technologies at the Graniterock Asphalt Plant at Aromas, CA; monitoring the construction of a test track; accelerated pavement testing with the Heavy Vehicle Simulator (HVS) to assess early rutting performance; and a comprehensive laboratory investigation to compare laboratory and HVS performance. The research has been documented in a report. Phase 2 of the study, which includes moisture sensitivity testing with the HVS and additional laboratory testing, is currently in progress. |
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Important Note for Caltrans Users: Prior to scheduling pavement preservation (preventive maintenance or CAPM) or roadway rehabilitation work on flexible pavement highway sections, the District Materials Engineer and/or the Project Manager should review this spreadsheet to ensure that the proposed project does not include sections active in the “Quieter Pavement Research” (QPR) testing program. If the proposed project is within a QPR test section, please contact Linus Motumah of the Caltrans Office of Pavement Design before scheduling the work.
To view maps that show where the sections are located, click the following link: http://maps.google.com/maps?q=http://ucprc.ucdavis.edu/qpsectionsmap.kmz (or cut-and-paste it into a new browser window for a slightly larger view).
For more information, contact Erwin Kohler of the UCPRC or Linus Motumah.