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NEWS (Previous News Items)

  • The Inertial Profiler Certification Program is up and running. Six certifications have been performed since July 2013. The program, which is intended to ensure that qualified operators and profilers perform pavement QA testing, has certified 25 operators and 18 inertial profilers to date. Follow the links to see the lists of Certified Operators and Profilers. Posted 7/22/2014.
  • In June 2014, the UCPRC published the report “Evaluation of Grind and Groove (Next Generation Concrete Surface) Pilot Projects in California”. This report documents a field study undertaken for Caltrans to evaluate pilot projects where this new texturing technique was applied to existing concrete pavements to see whether it would produce quieter and smoother pavement surfaces. The study’s results, based on data collected on seven pilot projects in the Central Valley and San Diego, cover tire/pavement noise, smoothness, skid resistance, and cost, and offer preliminary recommendations regarding where it is most appropriate to use this texture. Posted 7/7/2014.
  • The International Symposium on Pavement LCA will be held in Davis, California, on October 14-16, 2014. Information on travel and conference hotels is now available. Information and registration are available here. Posted 11/27/2013.
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Winter and Spring 2014 UCPRC Activities

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Candidate for fully permeable shoulder retrofit validation site

Developing a Performance-Related Specification for Asphalt Rubber. The current Caltrans specification for wet-process rubberized binders includes both (a) field measurements of binder viscosity for quality control and (b) measurements of penetration, resilience, and softening point for acceptance. All the current test procedures used to make these measurements are empirical in nature and based on the viscosity of the binder. But while viscosity is an important parameter for the workability of the binder and of the mix, it is limited in that it only has an indirect relationship with the in-service performance of the binder within the mix. In addition, viscosity measurements alone lack sufficient accuracy to completely describe the complex properties of these wet-process asphalt rubber binders because of their particulate nature. Although the Performance Grading (PG) system for asphalt binders, developed by the Strategic Highway Research Program (SHRP) as a part of the Superpave mix design procedure, determines binder performance properties using a dynamic shear rheometer (DSR), this approach has been determined to be inappropriate for testing wet-process rubberized binders because of the limitations of the parallel plate testing geometry.

Together the UCPRC and a DSR manufacturer have developed a modified test procedure and equipment that can be used to evaluate the performance characteristics of wet-process rubberized binders. Using a newly developed optimized concentric cylinder for the DSR, the rheological properties of asphalt rubber with particle sizes up to 1.4 mm can be fundamentally characterized in line with the PG system using the proposed procedure. Among the other advantages of the new procedure are its ability to accommodate larger particle sizes, the removal of edge effect concerns, reduced operator error due to the elimination of the need for specimen trimming, and better temperature control. Preliminary laboratory results also showed superior repeatability compared to the parallel plate geometry used for conventional, terminal-blended asphalt rubber and polymer-modified binders. These more accurate performance-related binder property measurements are expected to prevent unexpected project failures and will result in cost savings for both owner agencies and material producers.


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://www.ucprc.ucdavis.edu/qpsectionsmap.kmz (or copy-and-paste it into a new browser window for a slightly larger view).

For more information, contact John Harvey of the UCPRC or Linus Motumah.