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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.

NEWS (Previous News Items)

• A Vision for the Future of the Pavement Enterprise. John Harvey, professor in Civil and Environmental Engineering and Director of the UC Pavement Research Center (UCPRC) presented the Rasmus S. Nordal keynote address to more than 400 delegates at the 10th Conference on the Bearing Capacity of Roads, Railways and Airfields in Athens, Greece, on June 28, 2017. Titled “Imposed vs. Chosen Change: A vision for the Future of the Pavement Enterprise,” the lecture looked at whether “stationarity”—the idea that the needs of future design can be based on past needs—applies to the future of pavement. The lecture reviewed expected changes in the demand for pavement for personal mobility and freight, the effects of projected vehicle technology changes on pavement, increased expectations and functional requirements that pavements will need to meet, and recommended changes in the academic and government sectors of the pavement enterprise to meet future demands and expectations. The presentation is downloadable here. Posted 7/7/2017.
• Local Government Pavement Research. Local governments bear responsibility for 80% of the roadway pavement lane-miles in California, which carry 45% of the vehicle miles traveled. However, these governments face a growing backlog of projects, and need new approaches to reduce the costs of preservation, maintenance, rehabilitation and reconstruction. They also need help improving their staff’s knowledge of the most cost-efficient and lowest environmental impact approaches to those tasks, and they need it delivered in ways that meet their needs. Currently, California does not have a well-organized systematic approach for delivering this technical content to local governments, but several other states do. The UCPRC recently helped complete a white paper that canvased other states to develop a summary of best practices and gaps in other states’ approaches for delivering technical pavement management content to local governments, and recommends an approach for California. The white paper is downloadable here. Posted 5/31/2017.
• Pavement Life-Cycle Assessment Symposium. In April, the Pavement Life-Cycle Assessment Symposium 2017 at the University of Illinois at Urbana-Champaign brought together more than 130 national and international experts from academia and industry, including researchers from the UCPRC. Discussions focused on implementing LCA for pavements globally, the current state of LCA implementation at project- and network levels, development of programs for Environmental Product Declarations, future plans and needs for pavement LCA, and more. Information and presentations are available at http://lcasymposium.ict.illinois.edu/program/. Posted 5/31/2017.
• 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.

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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.