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NEWS (Previous News Items)

  • New Tech Memo Published: Development of the CalME Standard Materials Library. “The main purpose of the project is to improve the ability of Caltrans pavement designers to use mechanistic-empirical (ME) pavement design procedures that were developed and calibrated for California conditions as part of Partnered Pavement Research Center Strategic Plan Element (PPRC SPE) 4.1 and refined in SPE 3.4. Specifically this project is part of a long-term series of tasks to collect regional materials data for use by Caltrans in ME flexible pavement designs and rehabilitations. This technical memorandum documents ...”
    Posted 4/19/2018.
  • New Tech Memo Published: Permeability Testing on Dense-Graded Hot Mix Asphalt (HMA) and Gap-Graded Rubberized Hot Mix Asphalt (RHMA-G) Surfaces. “Falling head permeability tests were conducted on seven projects, four with dense-graded hot mix asphalt surfaces and three with gap-graded rubberized hot mix asphalt surfaces. Tests were conducted between the two wheelpaths and in the right wheelpath, and in both directions of traffic. Averaging all the test results shows that ...”
    Posted 3/26/2018.
  • New Guideline Published: Guidelines for the Selection, Specification and Application of Chemical Dust Control and Stabilization Treatments on Unpaved Roads. This guide introduces a new process for selecting an appropriate chemical treatment category for a specific set of unpaved road conditions using ranked potential performance. The process is based on a practitioner’s setting an objective for initiating a chemical treatment program and then gaining a fuller understanding of the road in terms of materials, traffic, climate, and geometry. Using the information collected, the most appropriate chemical treatment subcategories for a given situation can be selected from a series of charts and ranked using a simple equation. This process can be completed manually using a paper form, or by using a web-based tool. Matrices for each of the objectives were developed based on documented field experiments and the experience of a panel of practitioners. Guidance on specification language for procuring and applying unpaved road chemical treatments is also provided, along with comprehensive guidance on understanding unpaved road wearing course material performance.
    Posted 3/20/2018.
  • The Beguiling Science of Making Planet-Saving Pavement: Changing how we make the pavements we walk and drive on could make a real dent in California’s greenhouse gas emissions output, according to a Wired magazine article that cites UCPRC and its lifecycle studies. UC Davis Civil & Environmental Engineering Professors Alissa Kendall and John Harvey, Director of UCPRC, are both quoted: https://www.wired.com/story/pavement-environment-science.
    Posted 2/5/2018.
  • New Tech Memo Published: Performance Based Specifications: Literature Review on Increasing Crumb Rubber Usage by Adding Small Amounts of Crumb Rubber Modifier in Hot Mix Asphalt. “A comprehensive review of the literature covering more than 100 published journal articles, conference proceedings, and reports found that although considerable research has been undertaken to understand the advantages and disadvantages of using recycled tire rubber to modify asphalt binders, no published information on PG+X-type initiatives (i.e., focused more on using additional waste tires in asphalt mixes rather than on improving performance of the binder and mix) was found. A number of states ...”
    Posted 1/25/2018.
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Fall 2017 UCPRC Activities

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Candidate for fully permeable shoulder retrofit validation site

Updating the Weigh-In-Motion (WIM) Spectra of the California Highway Network. Weigh-In-Motion (WIM) devices measure and record the axle loads of vehicles on the highway. The data they collect include axle loads and spacing, vehicle classification and gross weights, and travel speed. These WIM data are utilized for pavement design, pavement management, and performance studies (Figure 1). In 2016, there were 132 WIM devices operating on California’s highway network, which is one of the densest and best maintained networks in the country.

The UCPRC has been working with Caltran’s WIM data since 2007 to advance mechanistic-empirical (ME) pavement design procedures. A UCPRC analysis of WIM data completed in 2008 used measurements from 1998 to 2003 to look for similarities in axle load distributions at a number of WIM sites and grouped them to generate default traffic inputs for pavement design software. In 2017, the UCPRC processed WIM data collected from 80 California WIM-measuring sites from 2004 to 2015, identified the axle load distribution for each site, and updated the earlier groupings using logical cluster analysis. A decision tree was developed to classify WIM data into five WIM axle load spectra, which have been implemented in the Caltrans pavement management system database, PaveM, and to generate truck traffic inputs in the CalME and MEPDG pavement design software tools used by Caltrans for asphalt and concrete pavement design, respectively.