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NEWS (Previous News Items)

  • EPD Workshop Report. An FHWA-sponsored workshop on Environmental Product Declarations was held September 13-15, 2016, at the Michigan Technical University research offices in Ann Arbor, Michigan. The goal of the workshop was to assess the prospects and obstacles for production of Environmental Product Declarations (EPD) by industry, and their use by public and private owners. The workshop included gatherings that focused on three primary concerns. The first was the global benchmarking of the ability of industry to produce EPDs and of owners to use EPDs. The second sought to identify the institutional barriers, technical gaps, human resource and level-of-expertise capacity limitations, and cost constraints holding back the development of uniform standards and approaches to collecting, organizing, and documenting data inventories that are in keeping with the data quality standards outlined in ISO 14025, and implementation of ISO 14025 in the European EN 15804 standard, and recently published FHWA Pavement LCA guidelines. Third, participants worked to create a vision for the future production and use of EPDs that includes solutions for standardization, strategies for overcoming barriers and gaps, and ideas for constraining costs. In plenary presentations, workshop participants framed the issues and posed questions that were addressed in workshops that followed (and where further questions were sometimes raised). Final day discussions focused on developing the outline of a draft road map for a way forward. The report from the workshop is available here. Posted 2/28/2017.
  • Bicycle Ride Quality Study. To identify pavement treatment surfaces that are more acceptable to California’s increasing number of bicyclists as well as safe for motorists, the UCPRC undertook and recently completed the second part of a Caltrans-sponsored study into roughness and surface textures that could satisfy both sets of road users. A report on the study is now available. It contains a set of recommended guidelines that can be used to select pavement surface treatments for both urban and rural roads that maximize bicycle ride quality based on surface texture, combined with the effects of road roughness. This multi-faceted study built on the earlier study by including a wider range of bicycle types and riders, and considering urban preservation treatments and city streets as well as treatments used on state highways and county roads. The recommendations in the study are based on user surveys as well as investigation of the effects of preservation treatment aggregate gradations on surface texture and the mechanistic responses of bicycles to pavement macrotexture and roughness. Posted 2/13/2017.
  • HMA Performance-Based Specifications Tech Memos. Three new technical memos are now available that document Caltrans-sponsored UCPRC research on projects whose aim is the development of HMA performance-based specifications for long-life pavements. The memos provide the study’s results and describe how Caltrans and the UCPRC collaborated to finalize the mix designs, perform laboratory mix testing, and establish performance criteria for two long-life pavement projects in Caltrans District 2 (one north of the city of Red Bluff and another north of the city of Weed) and one in District 4 (on Interstate 80 in Solano County). Caltrans put the resulting data to use by making it available to contractors bidding to construct the projects and by having its staff pavement designers use it with CalME flexible pavement design methodology. Now that the projects are in place, Caltrans has continued the follow up performance monitoring included in the memos’ recommendations. Posted 11/8/2016.
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Spring 2017 UCPRC Activities

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Candidate for fully permeable shoulder retrofit validation site

Full Depth Reclamation: Shrinkage Crack Mitigation Methods for Cement Stabilized Layers. Full depth reclamation (FDR) has been used for rehabilitating pavements in California since 2001. The FDR layers are stabilized with foamed asphalt (FDR-FA) or portland cement (FDR-PC) to improve the rut resistance, fatigue life and moisture susceptibility of the layers. This study focused on addressing the well-known concern of early age shrinkage cracks in cement stabilized layers, using a process known as microcracking. Microcracking was first investigated in Austria in the 1990s, and further developed in Texas from 2003. It involves applying vibratory roller passes on the cement treated layer, two to three days after construction with the goal of reducing the rate of curing in the cemented layer to decrease layer stiffness by creating a fine network of cracks throughout the layer, which relaxes the initial tensile stresses caused by cement hydration.

This Caltrans/UCPRC study was launched to refine the current method specification required in the 2015 Caltrans standard specifications. This specification requires three 12-ton vibratory roller passes at maximum amplitude, two to three days after construction. The specification does not consider different mix designs, and no testing is required to validate the microcracking effort. The development of laboratory methods to determine the optimum method for microcracking, and mechanistic models to determine the effect of microcracking on pavement life were also included in the project objectives.

The study was approached in two phases. The first was started in the summer of 2014, with the goal of modeling microcracking in the laboratory and monitoring stiffness changes over time on a number of field projects. The second phase covered the construction, instrumentation, and intense evaluation of a 1.1 mile long test road with 37 test sections covering a range of variables including cement content, and timing and intensity of the microcracking. Controls with no microcracking were included for comparison.

The test road was constructed during the summer of 2016 on Levee and Brooks Roads on the UC Davis campus. The road is visually monitored for shrinkage on a weekly base. Stiffness testing with a falling weight deflectometer is conducted frequently to observe the differences in stiffness gain on the different sections. Laboratory testing is being conducted in parallel with field monitoring to simulate field performance and to develop mechanistic models of microcracking and to predict performance of pavements with microcracked FDR-PC layers.


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.