Welcome from Structures TOC Chair

Welcome to the August 2009 edition of the WHRP E-News, a quarterly update from the Wisconsin Highway Research Program. 

I have been with WisDOT for eight years in the development section of the Bureau of Structures. I currently serve as the chair of WHRP’s Structures Technical Oversight Committee. One of the main goals for our TOC is to initiate research projects that produce results WisDOT can directly implement into practice, which can include designing, constructing and maintaining our inventory of bridges. Recently, we’ve had several projects that achieved that goal, including research to:

• Develop design coefficients of friction for stainless steel/Teflon bridge bearings
• Better understand permit vehicle weights in Wisconsin and update the Standard Permit Vehicle configuration
• Evaluate the effectiveness of wrapping deteriorated bridge columns with a fiberglass-composite material as a repair technique
• Create specifications for fiber-reinforced deck forms for use on wide-flange prestressed girders

The results from these and many other projects demonstrate the success WHRP has had in improving Wisconsin highways and bridges. As we begin Fiscal Year 2010, the Structures TOC looks to ongoing and upcoming research efforts (see the FY 2010 program in the May E-News) to continue to deliver practical solutions for the state’s most critical bridge issues.

Travis McDaniel
WisDOT Bridge Engineer
Chair, Structures TOC
travis.mcdaniel@dot.wi.gov
(608) 266-5097

Program Update

Redesigned WHRP Web Site

WHRP has a new look online. You can still find us at www.whrp.org, but we’ve redesigned our Web site to make it easier for all users to find just what they’re looking for. Practitioners and other highway stakeholders can quickly locate information on completed research, ongoing research and implementation activities sorted by research areas. We’ve also centralized investigator resources, putting everything from Requests for Proposals to reporting requirements in one location.

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MEPDG Efforts Move Forward

WHRP recently released a research needs white paper that defined opportunities for WHRP to support WisDOT in implementing the Mechanistic-Empirical Pavement Design Guide. The white paper identified two potential areas for collaboration: local calibration of the MEPDG and development of catalogs of material properties. Since then, WHRP has made significant progress in both areas.

Local Calibration. WHRP is assisting the WisDOT Bureau of Technical Services in administering the second phase of implementing the MEPDG in Wisconsin. The project focuses on local calibration of the MEPDG models used to predict various types of pavement distress. The approach uses the actual materials and pavement performance history of jointed plain concrete and hot-mix asphalt pavements throughout the state.

The expected end date of this project is July 30, 2010. For more information on this project, contact Steve Krebs or Andrew Hanz.

Catalogs of Material Properties. The WHRP technical oversight committees selected three research projects for Fiscal Year 2010 that specifically relate to developing material properties catalogs to support MEPDG implementation:

• “HMA Fatigue and Low Temperature Properties to Support MEPDG,” Ramon Bonaquist, Advanced Asphalt Technologies (Flexible Pavements TOC)
• “Investigation of Testing Methods to Determine Long Term Aggregate Durability of Various Types of Wisconsin Aggregate Sources,” Habib Tabatabai and Hani Titi, UW–Milwaukee (Geotechnics TOC)
• “Laboratory Study of Concrete Properties to Support Implementation of the New AASHTO Mechanistic-Empirical Pavement Design Guide,” Steven Cramer and Marc Anderson, UW–Madison (Rigid Pavements TOC)

Establishing conventional values for material properties will give pavement designers at WisDOT the data they need to decide how best to use the MEPDG to meet the state’s needs.

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All Projects at a Glance

As of June 30, 2009, there were 25 active WHRP projects. Four projects were completed during the last three months.

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Research in Focus

Improving Bearing Capacity Predictions for More Efficient Piles
0092-07-04, Comparison of Five Different Methods for Determining Pile Bearing Capacities

Predicting the bearing capacity of the piles that support Wisconsin’s bridges and other structures is a critical engineering challenge. If predictions are inaccurate, then either piles will not be driven deeply enough, leaving the structure unsafe, or driven too deeply, which wastes time, labor and materials.

Current WisDOT practice uses a capacity prediction method that incorporates a factor of safety in estimating safe bearing loads for piles, which overuses resources. Continuing to use the same formulas while transitioning to AASHTO’s Load and Resistance Factor Design method would be very costly, requiring much more piling to be driven into the ground. To address this, WHRP initiated a research project to compare WisDOT’s current formula for predicting capacities with alternate formulas developed by FHWA and other sources.

A research team led by professor James Long of the University of Illinois at Urbana-Champaign compared pile bearing capacity predictions computed using the alternate formulas against real-world capacity measurements in Wisconsin databases. They found a modified version of the FHWA-Gates formula and a formula developed by Washington State DOT to be the most efficient predictors. Based on their findings, investigators recommended that WisDOT replace its current capacity prediction method with this more accurate methodology (draft specifications under development are a part of WHRP implementation project 0092-08-37). The increase in accuracy will save Wisconsin taxpayers money while providing more precise engineering practices, helping to ensure that newly constructed bridges will be safe.

For details, see the study’s project page or contact Jeff Horsfall, WisDOT Bureau of Technical Services, at (608) 243-5993.

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Testing Wisconsin’s Pavement Mix Designs
0092-08-06, Wisconsin Mixture Characterization Using the SPT on Historical Aggregate Structures

As Wisconsin moves forward in implementing mechanistic-empirical pavement design—which seeks to optimize pavement designs for specific anticipated traffic and environmental factors—it is important to understand the characteristics of HMA mix designs already in common use in the state.

WHRP initiated a study to test a representative set of mix designs using standardized procedures to evaluate the rutting resistance and stiffness of these asphalt mixtures through measurement of Flow Number and dynamic modulus. These measurements can serve as an input to M-E design, providing a baseline for identifying successful material performance and allowing correlation between material properties and available pavement performance data for Wisconsin’s roads. The data will provide Wisconsin with a tremendous benefit by identifying which mix designs result in high-performing, long-lasting pavements and contributing to MEPDG implementation efforts

Investigator Ramon Bonaquist of Advanced Asphalt Technologies used AASHTO-developed procedures and equipment known as the Asphalt Mixture Performance Tester (formerly the SPT, or Simple Performance Tester) to generate modulus curves and other material properties for 12 high-performing asphalt mixtures representing typical Wisconsin mixture designs. The specimens were mixed, compacted and cored to required AMPT standards, and mixtures were cataloged based on geographic location, aggregate source and type, specific material properties, and other criteria. These results were then compared against historical WisDOT field performance data.

The study provided support for WisDOT’s current pavement designs and resulted in a mix catalog and analysis that will allow for evaluation of new mixtures in light of existing ones. It also demonstrated the significant improvement in performance from using polymer-modified asphalt binders. In July, WHRP held a Knowledge Transfer Workshop to communicate the findings of this study to WisDOT pavement designers.

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Regional and National

Recycled Materials Resource Center

Headquartered at the University of New Hampshire and jointly staffed with UW–Madison faculty, the FHWA-funded Recycled Materials Resource Center evaluates guidelines for increasing the use of recycled materials in transportation infrastructure, including construction and maintenance. The RMRC takes advantage of research expertise at both universities: transportation infrastructure and geotechnical engineering at UW–Madison, and environmental aspects of recycled materials and life-cycle analysis methods at New Hampshire.

RMRC is closely aligned with WHRP in both philosophy and approach. The most recent five-year strategic plans for all four WHRP TOCs call for research into increased use of recycled materials and industrial byproducts, and other innovative uses of materials.

WHRP researchers are involved in RMRC efforts. Craig Benson, professor of Civil and Environmental Engineering at UW–Madison, is the co-director of the RMRC, and CEE professor Tuncer Edil is the director of research. Both Benson and Edil have served as investigators for multiple WHRP research projects.

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MARC Puts Green Asphalt Issues in Focus

This spring, UW–Madison formally approved the establishment of the Modified Asphalt Research Center. Among MARC’s next steps will be to hold discussion forums with faculty members and representatives of the modified asphalt community (including several WHRP members) to define and prioritize the most critical research needs for the center.

As MARC researchers move forward with these plans, they will address two driving forces in the development and deployment of modified asphalts: environment and sustainability. As a follow-up to its white paper on the topic, MARC is focusing on these key points:

• Bring attention to green construction. While the climatic and environmental impact of the transportation system as a whole has become a top-of-mind issue, discussions of climate change and energy consumption seldom focus on pavement construction methods and techniques. Sustainable pavements need to be part of the solution to minimize transportation’s energy consumption, emissions and environmental impact.

• Define the metrics of sustainability. Rapid deployment of sustainable paving methods and technologies depends on understanding where the industry currently stands on key sustainability indicators. Identifying information shortages will help bring researchers, material manufacturers, contractors and road authorities to a consensus on metrics used to evaluate pavement sustainability.

• Innovate through collaboration. Existing methods to quantify pavement sustainability can be supported by data derived from a variety of sources and techniques. The scientific community should foster research, innovation and entrepreneurship in difficult economic times through international collaboration.

In support of these and related issues, MARC research is focused on identifying, testing and validating alternative pavement technologies that show promise in reducing energy consumption. Initial efforts have modeled energy consumption in manufacturing processes and investigated quantitative life-cycle analysis tools for assessing pavement sustainability. Upcoming research efforts will investigate performance characteristics and behaviors of low-energy asphalt mixes.

For more information about MARC, contact Hussain Bahia or Carl Johnson.

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TRB Publications Related to WHRP Research

WHRP has identified a select list of Transportation Research Board publications from the past three months, primarily from the National Cooperative Highway Research Program, related to WHRP research areas.

• Nondestructive Testing Technology for Quality Assurance of Hot Mix Asphalt Pavement Construction, NCHRP Report 626
• Guide for Pavement Friction: Background and Research, NCHRP Research Results Digest 321
• Guide for Pavement Friction, NCHRP Web-Only Document 108
• Implementation Status of Geotechnical Load and Resistance Factor Design in State Departments of Transportation, Transportation Research Circular E-C136

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Outreach

Asphalt Mixture Performance Tester Workshop and Webinar

Last month WHRP hosted a Knowledge Transfer Workshop for all individuals interested in the results of a recently completed research project on the Asphalt Mixture Performance Tester (see the article above). The half-day event was held July 22 in Madison. Agenda highlights included:

• WHRP Welcome and Introduction – Hussain Bahia, WHRP
• WisDOT Selection of Research Materials – Tom Brokaw and Judie Ryan, WisDOT
• National Roadmap Directions for HMA – Erv Dukatz, Mathy Construction
• Research Project Overview and Q&A – Ramon Bonaquist, Advanced Asphalt Technologies

To better accommodate participants from across the state, WHRP broadcast the entire workshop online as a live webinar. In addition, presentations and streaming video of the webinar have been posted to the WHRP Web site.

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Surveys to Identify Research Needs

In its commitment to conducting research with implementable results, WHRP continues to seek guidance from Wisconsin’s highway practitioners. WisDOT engineers and consulting engineers alike help identify research needs each year through a survey process. These online surveys have been a very effective way for WHRP to identify and address gaps in research. Of particular interest are research topics whose results could have an impact on WisDOT’s specifications.

This summer and fall, WHRP plans to issue updated surveys of research needs in the areas of Flexible Pavements and Rigid Pavements, with new surveys in the areas of Geotechnics and Structures to follow. Look for an announcement from WHRP, and thanks for participating. Your thoughtful input is critical in helping WHRP achieve its mission.

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Warm-Mix Asphalt & Recycling Symposium

The National Asphalt Pavement Association hosted the Warm-Mix Asphalt & Recycling Symposium June 8 to 10 in Sacramento, Calif. A wide range of stakeholders, including state DOTs, FHWA, industry and researchers, gave presentations and shared perspectives on WMA technology. Presentations addressed results of field trials, accelerated performance testing, best practices at asphalt plants and paving sites, energy conservation, and emissions reductions.

Presenters shared information about software developed to estimate energy savings due to lowering HMA production temperatures as well as emission reductions from careful monitoring of production methods. Other sessions on energy and recycling addressed such issues as reclaimed asphalt pavement, recycling materials other than RAP, and building perpetual pavements using rubblized bases.

Among the presenters was WHRP researcher Ramon Bonaquist of Advanced Asphalt Technologies, who gave a talk titled “An Approach to WMA Mix Design..” WHRP Technical Director Hussain Bahia also attended the event and gave a talk on use of foundry sand and recycled tire rubber in asphalt mixtures.

For more information, see the symposium’s Web site or contact Hussain Bahia.

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Implementing Research

Encouraging HIPERPAV Use in Wisconsin
0092-08-33, HIPERPAV Wisconsin Implementation Support, Phase IIb

The early-age properties and behavior of fresh concrete can have a critical impact on the durability of new pavements. FHWA’s HIPERPAV software simulates the 72-hour period after concrete placement, allowing engineers to evaluate the effects of design, materials, environment and construction factors on early-age concrete pavements.

In a 2006 WHRP project (0092-04-11), researchers customized HIPERPAV to Wisconsin’s design and construction practices in order to increase its usefulness for Wisconsin engineers. Mauricio Ruiz of The Transtec Group is leading an implementation of this research to incorporate HIPERPAV into daily construction practices in Wisconsin. Researchers are currently analyzing field and laboratory data to verify the accuracy of the software’s predictions for Wisconsin fly ash used in concrete mixes. They are also providing technical support to HIPERPAV users in Wisconsin, promoting its use throughout the state, and continuing to enhance the software in response to the needs of contractors. In a final report due this summer, researchers will evaluate the accuracy of the modified software’s predictions of field performance.

Future phases of implementation may include changes to WisDOT policies and specifications; more detailed testing and characterization of local materials; development of databases of materials and mix designs; local validation of the software’s accuracy; and workshops and technology transfer.

If adopted by WisDOT and its contractors, HIPERPAV could help facilitate a systematic approach to maximizing concrete pavement quality, optimizing construction procedures and controlling costs.

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About WHRP
www.whrp.org

The Wisconsin Highway Research Program was established in 1998 by the Wisconsin Department of Transportation to conduct research on highway materials and construction methods. WHRP is administered by the UW-Madison Department of Civil and Environmental Engineering. A Steering Committee chaired by the WisDOT Research Administrator provides policy direction to the WHRP Technical Director, Program Manager and four Technical Oversight Committees chaired by WisDOT engineers. The TOCs focus their work on Flexible Pavements, Rigid Pavements, Geotechnics and Structures. The Steering Committee and TOCs are composed of representatives from WisDOT, FHWA, academia and industry.

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