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NEWS (Previous News Items)

  • Upcoming Symposium, January 13-15, 2021: International Symposium on Pavement, Roadway, and Bridge Life Cycle Assessment 2020. Due to the current pandemic COVID-19, the International Symposium on Pavement, Roadway, and Bridge Life Cycle Assessment 2020, has been rescheduled to January 13-15, 2021, and will now be held in Davis, CA. The symposium will cover such areas as recent advances in quantifying environmental impacts using LCA for pavement, roadways, and bridges; current status and future developments; and standardization and implementation of pavement, roadway, and bridge LCA. Registration is Now OPEN.
    Posted 12/13/2019; Updated 4/24/2020.
  • New Tech Memo Published: Life Cycle Assessment and Life Cycle Cost Analysis for Six Strategies for GHG Reduction in Caltrans Operations. “California state government has established a series of mandated targets for reducing the greenhouse gas (GHG) emissions that contribute to climate change. With a multiplicity of emissions sources and economic sectors, it is clear that no single change the state can make will enable it to achieve the ambitious goals set by executive orders and legislation. Instead, many actors within the state’s economy–including state agencies such as the California Department of Transportation (Caltrans)–must make multiple changes to their own internal operations. The focus of this study and technical memorandum is to examine several strategic options that Caltrans could adopt to lower its GHG emissions...”
    Posted 10/8/2020.
  • New Research Report Published: Development of Performance-Based Specifications for Asphalt Rubber Binder: Interim Report on Phase 1 and Phase 2 Testing. “In the United States, the Superpave Asphalt Binder Performance Grading (PG) system proposed by the Strategic Highway Research Program (SHRP) is the most common method used to characterize the performance-related properties of unmodified and polymer-modified asphalt binders. Dynamic shear modulus (G*) and phase angle (δ) are the two main binder properties and they are measured using a dynamic shear rheometer (DSR) with parallel plate geometry and either a 1-mm or 2-mm gap between the plates. Since these Superpave parameters were developed for binders that do not contain additives or particulates, the California Department of Transportation (Caltrans) does not use them for asphalt rubber binder specifications. Instead, penetration...”
    Posted 10/8/2020.
  • New Research Report Published: Optimizing Rubberized Open-graded Friction Course (RHMA-O) Mix Designs for Water Quality Benefits: Phase I: Literature Review. “Historically, rubberized and non-rubberized open-graded friction courses (OGFCs) have been placed to provide three benefits: to increase traffic safety, to reduce urban highway noise, and to preserve the surface of the main pavement structural section. However, stringent environmental regulations on stormwater runoff management enacted recently have forced transportation agencies with limited right of ways in urban areas to search for creative methods to treat runoff and receive credits for preventing pollution from highways. This literature review was undertaken to explore ways to optimize current RHMA-O mix designs...”
    Posted 9/16/2020.
  • Caltrans/UCPRC Asphalt PRS Road Map: Performance Related Specifications for Asphalt Superpave and QC/QA. The Caltrans/UCPRC road map for development of performance related specifications (PRS) for asphalt pavement materials, integrated with mechanistic-empirical (ME) design and balanced mix design, was discussed at the Federal Highway Administration stakeholder workshop (August 11-13, 2020) on this subject. Stakeholders at the workshop were FHWA, state DOTs, the asphalt pavement industry, and university researchers.
    Posted 8/13/2020.
  • New White Paper Published: Alternative Strategies for Reducing Greenhouse Gas Emissions: A Life Cycle Approach using a Supply Curve. The purpose of this white paper is to provide Caltrans with a methodology that uses life cycle assessment and life cycle cost analyses to create a “supply curve” that ranks different strategies and actions the agency can take to reduce greenhouse gas emissions and lessen the detrimental environmental impacts to ecosystems and human health. Before Caltrans can implement this proposed methodology, it must be validated and assessed using several alternative strategies that Caltrans is considering or might consider. The strategies evaluated were selected by the authors based on information available to them, and do not necessarily reflect Caltrans policies or priorities. This white paper presents the methodology and demonstrates its initial use in quantifying and ranking several potential strategies.
    Posted 8/12/2020.
  • New Research Report Published: Development of Improved Guidelines and Designs for Thin Whitetopping: Environmental Response of Full-Scale BCOA Sections. “Fifteen bonded concrete overlay of asphalt (BCOA) sections were built at the UCPRC facility in Davis, California, from February 23 to 25, 2016. The concrete mixes included Type II/V and Type III portland cements and calcium sulfoaluminate cement, and they were designed to provide 2.8 MPa (400 psi) flexural strength after either 4 or 10 hours. Six of the 15 sections were instrumented with a total of 245 sensors to measure the responses to environmental actions and cement hydration. Based on the analysis of the data collected by these sensors up until May 31, 2017, preliminary conclusions were drawn regarding how the different section configurations and concrete types responded to moisture and temperature-related actions. A clear link between drying shrinkage, concrete relative humidity, and environmental conditions was verified. Very high levels of drying shrinkage were measured...”
    Posted 5/18/2020.
  • New Tech Memo Published: Development of Thin Bonded Concrete Overlay of Asphalt Design Method: Evaluation of Existing Mechanistic-Empirical Design Methods. “The California Department of Transportation (Caltrans) is interested in advancing the technology needed to implement thin bonded concrete overlay of asphalt (BCOA) on its road network. Recent accelerated pavement tests showed that thin BCOA exhibited promising results for structural performance and constructability in California’s dry environment when made with the high early-strength concrete mixes typically used by Caltrans. However, to continue moving forward, Caltrans needs to adopt a thin BCOA design method since the current Caltrans Highway Design Manual does not consider this type of pavement. In order to help Caltrans decide how to adopt a thin...”
    Posted 4/24/2020.
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Winter 2020 UCPRC Activities

Candidate for fully permeable shoulder retrofit validation site

Caltrans Thin Bonded Concrete Overlay of Asphalt (BCOA) Pilot Project. First Caltrans thin bonded concrete overlay of asphalt (BCOA) has been recently built in SR113 at Woodland, District 3. Thin BCOA, formerly known as thin whitetopping, is a pavement rehabilitation technique that consists of placement of a 4 to 6 in. thick concrete overlay on an existing flexible or composite pavement.

Caltrans thin BCOA pilot includes two stretches of SR113: PM 11.8-12.8 and PM 14.7-17.6. The latter was paved on October-November, 2018, while the former was paved on April-May, 2019. The design section of the project includes 6 in. thick concrete overlay on the milled asphalt base, 6 ft transverse joint spacing, and widened slabs. The overlay was built with a rapid strength concrete that was designed to provide 450 psi flexural strength (requirement for opening to traffic) in 24 hours. The pilot project includes also the use of new rubberized asphalt mix as a base.

The early field performance of the thin BCOA pilot is being monitored as part of Caltrans 3.39 Partnered Pavement Research Center project. The monitoring is focused on slab cracking, longitudinal unevenness, and transverse joint faulting and load transfer efficiently. To help the monitoring process, the pavement has been instrumented with a total of 110 sensors, which will be measuring concrete and asphalt strain, concrete and asphalt temperature, and concrete internal relative humidity.

It is expected that the monitoring of the construction and the early field performance of this pilot project will help to identify best and improved practices and standards applicable to California’s climate, materials, and construction work zone practices.