Highway Quality Compendium

Achieving Concrete's Full Potential

by Theodore R. (Ted) Ferragut, Dale Harrington, and Marcia Brink

The CP Road Map represents a long-term plan for research and technology development for PCC pavements.

For most of the 20th century, engineers used the same tried-and-true materials in designing concrete pavements-portland cement, high-quality aggregate, and water-with only minor refinements. "Designers used a fairly forgiving formula that allowed minor variations in subgrade quality, construction practices, and other variables, without sacrificing pavement performance," says Director Tommy Beatty of the Office of Pavement Technology at the Federal Highway Administration (FHWA).

During much of that time, the industry enjoyed the luxury of keeping traffic off the new pavements for several days, even weeks, while the concrete developed its internal strength. Over the last 15 years, however, the industry has experienced more changes than in the previous 80 years, turning the process of building concrete pavements on end, Beatty says.

Today's concrete mix designs, for example, need to integrate a multitude of new materials-including fly ashes and chemical admixtures like water reducers, retarders, and accelerators-which can cause challenges in compatibility and reduce the tolerance for variations in aggregate moisture content, materials temperatures, weather conditions, and other variables.

In addition, motorists are more demanding, tolerating only minimal closures and delays due to roadwork and increasing the need for new paving methods that enable crews to get in, get out, and stay out. And motorists want smoother and quieter pavements, which is pushing the paving industry to exercise greater control on the characteristics of the road surface.

Increasingly, highway agencies are shifting their focus from building new pavements to rehabilitating and maintaining existing ones, which requires different designs, systems, materials, and equipment. Environmental pressures, as well, affect mix designs and construction practices, as crews work to reduce traffic congestion and manage drainage and runoff.

Further, highway budgets are being squeezed at every level, and the pavement community simply must do more with less. "In this environment, the old system for constructing concrete pavements simply does not work anymore," says Beatty. "To achieve concrete pavement's full potential in this changing world, the industry cannot continue business as usual."

To help the industry grow and meet the challenges of the 21st century, FHWA, Iowa State University, and many other partners collaborated to create the Long-Term Plan for Concrete Pavement Research and Technology. Dubbed the CP Road Map, the plan represents a comprehensive and strategic approach to research that will guide investment over the next several years and spawn a new generation of concrete pavements.

What Is the CP Road Map?

"The CP Road Map gives the concrete pavement community an opportunity to proactively reinvent itself through research," says Peter A. Kopac, research highway engineer at FHWA.

By combining more than 250 research problem statements into 12 fully integrated, sequential, and cohesive tracks of research, the project team expects that the CP Road Map will lead to specific products that will dramatically affect the way that concrete pavements are designed and constructed. The innovative track structure and cross-track integration will at once help the research teams focus on their designated tasks and effectively share information where tasks overlap.

A project team led by Iowa State University prepared the CP Road Map on behalf of FHWA, with backing and participation from stakeholders in the concrete pavement industry, State departments of transportation (DOTs), and academia.

"In a very real sense, the authors of the CP Road Map include hundreds of stakeholders from State DOTs, materials supply companies, construction contractors, research and technology transfer universities, and other organizations," Kopac says. "For the men and women who face the daily realities and challenges of constructing and maintaining concrete pavements, this is their CP Road Map."

The project stakeholders will pool their resources to jointly conduct and coordinate the research, and an innovative implementation strategy will help move useful new products and systems into the field quickly.

Drawing a New Map

The Iowa State University-led project team facilitated development of the CP Road Map through a deliberate and inclusive process. First, the team created a "living" database of existing research, cataloging recently completed and inprogress projects and their products. Regularly updated and maintained, the database will serve as a valuable resource for many years.

Next the team gathered face-to-face input from the highway community, identifying research gaps that would become the basis for problem statements. The Iowa team hosted five brainstorming and feedback sessions at major industry events: the October 2003 meeting of the Midwest Concrete Consortium in Ames, IA; a special November 2003 regional workshop for eastern and southern stakeholders in Syracuse, NY; the May 2004 meeting of the American Concrete Pavement Association in Kansas City, MO; a special January 2004 regional teleconference for western stakeholders; and, in October 2004, a final meeting of national stakeholders hosted by FHWA at the Turner-Fairbank Highway Research Center in McLean, VA.

Through these events, plus presentations at more than 20 professional conferences and workshops across the country, more than 400 engineers and managers provided direct input into the CP Road Map. In addition to the organizations noted earlier, other participants included representatives from FHWA, State and local DOTs, the Portland Cement Association, the American Association of State Highway and Transportation Officials, the National Ready Mixed Concrete Association, Transportation Research Board and National Cooperative Highway Research Program committees, the American Public Works Association, the National Association of County Engineers, contractors, materials suppliers, universities with departments conducting applied research, and private concrete-testing laboratories.

The project team asked the participants to provide their insights in four broad categories: mixtures and materials, design, construction, and pavement management and business systems. Again and again, the stakeholders reported that they need improved analysis tools for measuring performance at every stage of the pavement system. They need to understand how and why pavements fail or succeed. Because variables in each stage affect the others, the methods and tools need to be integrated across stages, from mix and materials to design and construction, and with pavement management and business systems.

Based on these concepts of pavement performance and systems integration, the team proposed the following overall goal for the CP Road Map: By 2015, the highway community will have a comprehensive, integrated, and fully functional system of concrete pavement technologies that provides innovative solutions for customer-driven performance requirements.

Research Tracks

With abundant input from industry stakeholders and a strategic goal in hand, the project team identified dozens of specific research objectives and filtered them through the database of existing research to identify where gaps exist. The gaps became the basis for the 250 problem statements, which were added to the research database as work to be accomplished.

Team members organized the problem statements into 12 product-focused research tracks, which together form the long-term research plan. This structure captures the integrated, cross-category nature of the research and encourages stakeholder groups to step forward as champions for specific tracks. Research in one track often affects or is affected by research in another track, so team leaders for each track are responsible for ensuring that research is coordinated and integrated appropriately.

In addition to the defined tracks, the team leaders can sort information in the research database to isolate problem statements on a variety of subjects. Several problem statements, for example, are cross-referenced in multiple tracks, including those related to foundations and drainage systems, maintenance and rehabilitation, and advancements in environmental strategies.

Each of the 12 tracks is a complete research program in itself, with its own budget, two to seven subtracks, and as many as 20 problem statements. Tracks 1 through 9 consist of timed sequences of research leading to particular products that are essential to reaching overall research goals. Tracks 10, 11, and 12 are not phased because timing is not as critical.

One subtrack in every phased track is devoted to training tools and methods of technology transfer to ensure that innovative research products move into practice quickly and efficiently. The team defined the primary research tracks as follows:

1. Performance-Based Mix Design System. The final product of this track will be a practical yet innovative procedure for concrete mix design with new equipment, consensus target values, common laboratory procedures, and full integration with both structural design and field quality control-a lab of the future. This track also lays the groundwork for the concrete paving industry to assume greater responsibility for mix designs as State highway agencies move from method specifications to more advanced acceptance tools. For this move to be successful, the concrete paving industry and owner-agencies need a single document for the state of the art in mix design.

2. Performance-Based Design Guide for New and Rehabilitated Concrete Pavements. Under this track, the research community will expand the mechanistic approach to restoration and preservation strategies for concrete pavements, which involves using a structural response model to calculate pavement responses due to applied traffic and environmental loads. The track builds on and continues to develop the models created under the comprehensive National Cooperative Highway Research Program (NCHRP) Project 1-37A: Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures. The work in this track will be closely integrated with track 1.

3. High-Speed Nondestructive Testing and Intelligent Construction Systems. This track will develop high-speed, nondestructive quality-control systems to monitor pavement properties continuously during construction. As a result, workers will be able to make on-the-fly adjustments to ensure the highest quality finished product that meets given performance specifications. Many problem statements in this track relate to both tracks 1 and 2.

4. Optimized Surface Characteristics for Safe, Quiet, and Smooth Concrete Pavements. This track will result in improved understanding of the surface characteristics of concrete pavements. The research will provide tools to help engineers meet or exceed predetermined requirements for friction, safety, tire noise on pavements, smoothness, splash and spray, wheel path wear (hydroplaning), light reflection, rolling resistance, and durability (longevity). Each of these functional elements is critical. The challenge is to improve one characteristic without compromising another, while continuing to protect the safety of the public.

5. Equipment Automation and Advancements. This track will result in process improvements and the development of high-speed, high-quality concrete paving equipment to meet the concrete paving industry's projected needs and the traveling public's expectations for highway performance in the future. Examples include the next generation of concrete batching and placement equipment; behind-the-paver equipment to improve curing, surface treatment, and jointing; mechanized ways to place and control subdrains and other foundation elements; equipment to remove and replace the slab in one-pass construction; improved repair processes that decrease the time of operations and provide the workforce and traveling public with less exposure; and methods for evaluating new equipment on actual construction projects.

6. Innovative Joint Design, Materials, and Construction. Potential products for this track include a new joint design, high-speed computer analysis techniques for joint performance, a more accurate installation scheme, and faster rehabilitation strategies. The problem statements address the basics-joint design, materials, construction, and maintenance activities. The track also specifies research that will help develop breakthrough technologies and techniques for extremely high-speed joint repair. The team designed track 6 as a crosscutting track to ensure that all topics related to innovative joints are addressed. Much of the proposed research will develop important incremental improvements.

7. High-Speed Rehabilitation and Construction. To help develop faster techniques and higher quality for tomorrow's pavements, this track addresses a number of activities: the planning and simulation of high-speed construction and rehabilitation, precast and modular options, and fast-track construction and rehabilitation techniques for concrete pavement. The track also covers the evaluation and technology transfer of products and processes for high-speed construction and rehabilitation developed through research. Tracks 1 and 3 will likely involve the investigation of high-speed construction issues, so the CP Road Map project team will closely coordinate those efforts with track 7.

8. Long-Life Concrete Pavements. The need for longer lasting pavements that maximize the time between maintenance, restoration, or rehabilitation activities underlies all of the tracks in the CP Road Map. Track 8, however, draws attention to specific research that may lead to pavement life that approaches 60 years or more.

9. Accelerated and Long-Term Data Collection. This track provides the infrastructure-including data collection and reporting tools and testing methods-for a future national program that will plan accelerated loading and long-term data needs, construct test sections, and collect and share data. The problem statements in this track will identify the most useful data and determine the amount of time needed to collect that data.

10. Performance of Concrete Pavements. This track addresses key elements of pavement and asset management systems to determine whether pavements meet the performance characteristics that highway agencies and users desire. Research will determine and address the functional aspects of performance, particularly factors such as tire noise on pavements, friction, and smoothness. Research also will examine ways to schedule improvements to surface characteristics and conditions. Developing feedback loops in highway agencies' pavement management systems will be crucial to monitor performance quickly and effectively.

11. Business Systems and Economics. Roles and responsibilities are changing within the highway industry, affecting the way paving projects are designed, bid, built, and maintained. Increasingly State DOTs are asking contractors to assume greater control of the operation and quality-control inspections. By including warranty provisions in project contracts, owner agencies are asking for additional assurance that contractors are building pavements that will perform as expected. Many European countries like Spain and Great Britain have made dramatic changes in project funding methods and in the roles of contractors and suppliers. Track 11 captures important research that the industry needs to consider as this process of transformation continues in the United States. Problem statements cover contracting options, new technology transfer systems, public-private partnerships, and economic models.

12. Advanced Concrete Pavement Materials. The problem statements in this track address the development of new materials and refine or reintroduce existing advanced materials to enhance performance, improve construction, and reduce waste. Many of the existing materials studied in this track have been used only on a small scale or in laboratory evaluations. Many of them have not been used in the United States but show promise based on work completed in other countries. Track 12 will experiment with such materials on a larger scale and develop standards and recommendations for their use. The research will foster innovation in the development of additional new and innovative materials for constructing concrete pavements.

Reaching the Destination

Finally, the CP Road Map project team developed a management plan that outlines a progressive, cooperative approach to managing and conducting the research in the long-term plan. Under the management plan, participating organizations identify common interests, partner with one another to leverage funds and human resources, and execute specific contracts.

The research management plan is based on several assumptions. First, the CP Road Map is a national research plan for FHWA, State agencies, and industry, and it is not restricted to any single funding source. "Publicly financed highway research is decentralized and will probably remain so," says Director Dennis Judycki of the Office of Research, Development, and Technology at FHWA. "In a decentralized arena like research, it is critical for stakeholder groups to come together voluntarily. Federal, State, and industry research staff and engineers around the country are looking for more opportunities to pool their funds and other resources in win-win situations."

Under the management plan, communication, technology transfer, and outreach activities will avoid the all-too-common disconnect between research results and implementation. "Technology implementation must be elevated to the same level of importance as research itself," Judycki adds.

Finally, managing the CP Road Map effectively and judiciously will require full-time, dedicated personnel with adequate resources. The CP Road Map project team, therefore, developed a governing structure in the research management plan that outlines a four-tiered system of participation and responsibility.

A three-party executive advisory committee, representing FHWA, State DOTs, and industry organizations, will provide broad oversight. The executive advisory committee will serve as a decision- and policymaking entity and will have the following responsibilities:

• Assembling team leaders for each research track
• Promoting partnering arrangements
• Ensuring adequate integration of research across tracks
• Developing and implementing a strategy to ensure that software products developed through various research tracks will be compatible with each other
• Identifying new program areas for research
• Overseeing updates to and maintenance of the research database
• Developing a comprehensive program for technology transfer and training for products created through the CP Road Map
• Developing a communications effort to keep the CP Road Map and its products in front of stakeholders and the public
• Conducting self-evaluation studies
• Keeping the momentum focused on outcomes, not just output

An administrative support group will provide professional management services for the executive advisory committee. The administrative group will coordinate and support activities like maintaining the research database.

Team leaders for the research tracks will coordinate and oversee all activities within specific research tracks, such as validating and updating the track, developing broad problem statements into specific research projects, identifying organizations to conduct or partner in the research, and ensuring proper integration of work within the track and across track lines.

Finally, sustaining organizations, which include highway agencies, consultants, universities, professional associations, and other organizations that have specialized interests and skills and are interested in pooling dedicated funds, will assume responsibility for conducting research through cooperation, partnerships, and funding agreements. Sustaining organizations may retain full fiscal and technical control of the work under their jurisdictions.

Future Steps

FHWA intends to implement the roadmap in cooperation with all partners and stakeholders. The CP Road Map project team likens a long-term research program to turning an oceanliner around. The process involves a long, slow sweep. In this case, the team has turned the rudder-the CP Road Map-in the right direction. The next step is to fire the engines, full speed ahead.

"We see the CP Road Map as a living document that will help all of us-FHWA, the States, the concrete paving industry, and other stakeholders-work together to make the most of our investments in concrete pavement research," says Cheryl Allen Richter, technical director of pavement research and development in the FHWA Office of Infrastructure Research and Development. "We look forward to working with stakeholders throughout the concrete paving industry to maintain the Road Map and-more importantly-fire up those engines to get the research underway."

Reprinted from Public Roads, July/August 2005.