AN UPDATE ON ...
CONCRETE PAVEMENT RESEARCH PROGRAM
It’s an ambitious program directed
at advancing concrete pavement technology and construction methods.
by the staff of the American
Concrete Pavement Association
The program is the $30-million Concrete Pavement Technology Program,
funding for which was provided in the Transportation Equity Act for the
21st Century legislation. Many of the research programs in CPTP were
begun, and substantial work completed by the Innovative Pavement Research
Foundation under a cooperative agreement with the Federal Highway
Administration.
 Chartered in 1997, the IPRF mission is to provide applied research,
technology transfer, and public education on concrete pavements for
highways, streets, roads, and airports. IPRF is jointly sponsored by the
American Concrete Pavement Association, the Portland Cement Association,
and the National Ready Mixed Concrete Association.
The FHWA is carrying out the CPTP research in partnership with states,
industry, and academia. Through an oversight committee, the Transportation
Research Board acts in an advisory capacity for the research on concrete
pavements. The committee includes concrete contractors, material
suppliers, state Department of Transportation executives, academics, and
FHWA engineers, reports Suneel Vanikar, concrete pavement team leader at
the FHWA’s Office of Pavement Technology.
 The CPTP projects, more than 30 in all, address a range of topics
including: design/analysis, construction, and repair/rehabilitation of
concrete pavements; traffic management related to concrete pavement
construction and repair/rehabilitation; the compatibility of ingredients
in concrete mixtures; PCC overlays for rehabilitation of existing
pavements; life-cycle cost analysis; development of a long-term plan for
the concrete pavement research and technology program; computer-based
guidelines for optimization of paving concrete; design and use of precast
concrete pavement panels for construction and repair of concrete
pavements; non-destructive testing; performance-related specifications;
and pavement profile analysis.
 Each project in the CPTP is intended to result in one or more products
with potential for application in concrete pavement engineering practice.
The goal of assuring that all of these products reach the intended
end-users is, in itself, a major project. In fact, the FHWA has recently
advertised a special project, “Technology Transfer, Deployment, and
Delivery Services for the CPTP,” to achieve that goal.
Some examples of CPTP projects and products that are included in the
FHWA’s current and projected implementation activities include:
Performance prediction — HIPERPAV II is a software program
that predicts the long-term performance of jointed plain concrete pavement
as a function of early-age behavior. Workshops already have been conducted
in Pennsylvania, Iowa, and Michigan, Vanikar says.
Precast panels — Work is complete on evaluating the
feasibility of using precast concrete technology to expedite concrete
pavement construction. Precasting offers speed of construction and the
elimination of on-site curing of concrete pavement. A pilot project was
constructed in Texas, and additional pilot projects in California and
Missouri are being considered. A separate contract to research precast
concrete slabs for full-depth repair of deteriorated pavement joints was
awarded in March 2003, with installations planned in Michigan and Colorado
later this year.
Field trials — A project in California demonstrated weekend
reconstruction of a section of busy interstate and another tested an
ultra-thin whitetopping overlay to restore pavement serviceability. These
important rehabilitation techniques are captured for other potential users
in reports and videos. A similar field trial of UTW is planned in
Colorado. Both field trials were developed by the IPRF.
Analysis tools — The Aurora 2000 Pavement System is a software
package that was developed by industry to address concrete pavement
planning, design, construction, and economics. The software was
demonstrated at a technology transfer workshop in San Francisco, and
further evaluations of the software are being conducted for the FHWA. This
study was developed by the IPRF and was fully funded by the Portland
Cement Association.
Design features — Beyond concrete thickness and strength,
various features such as transverse joint design, base type, drainage
design, and shoulder type must be considered during the structural design
process. A project that will assist in determining the most cost-efficient
combination of design features for concrete pavement — considering
estimated costs and expected performance improvements of each feature —
has resulted in computer software that currently is being evaluated for
acceptance, Vanikar says. The vast majority of this project was developed
by the IPRF.
Technology workshops — Workshops on concrete pavement
technology were recently held for state DOT pavement engineers, one in
Breckenridge, Colorado, and another in San Francisco. Many positive
comments were received from participants. The two workshops were sponsored
by the IPRF.
Mobile Concrete Laboratory — The FHWA launched the MCL several
years ago to speed the transfer of new technology to highway agencies and
constructors. During fiscal 2003, the MCL evaluated the use of impact-echo
technology on existing concrete pavements to measure thickness, instead of
using destructive cores. The MCL staff has worked with DOTs in New Jersey,
Colorado, and Pennsylvania with recent presentations made in Texas,
Illinois, and North Carolina. MCL is committed to fiscal 2003 projects in
Florida, New York, and Pennsylvania.
Guidelines for repair/rehabilitation — Windows-based software
has been developed to provide guidelines that help evaluate existing
concrete pavements for repair or rehabilitation and help select materials
and techniques for optimal pavement performance and cost.
Ultra-thin whitetopping — Accelerated load testing of UTW has
been completed to verify design procedures, and pilot installations have
been made. The FHWA’s Accelerated Loading Facility at the Turner-Fairbank
Highway Research Center in McLean, Virginia, played a key role in this
development. This study was completed by the IPRF.
Workability test — A new workability test for concrete, called
the vibrating slope apparatus, which was developed by the U.S. Army Corps
of Engineers, has been further refined by the FHWA. The VSA quantifies
concrete workability by measuring the time it takes for a measured mass of
concrete to move out of a chute under certain levels of vibratory energy.
Airports research
Under a separate cooperative agreement between the IPRF and the Federal
Aviation Administration, a $6-million-plus research program is under way
to investigate the best design and most efficient construction of concrete
airport pavements. Federal funds for the airport research are generated
under the Aviation Investment and Reform Act for the 21st Century airport
funding legislation.
Today, the IPRF/FAA cooperative agreement has four research products to
report, says Jim Lafrenz, IPRF program manager. Five more research
projects were planned under a $1.88-million fiscal 2002 budget, and eight
projects have been identified under a fiscal 2003 budget of $3 million.
Following are four research products:
A manual: Best Practices for Airport Portland Cement Concrete
Pavement Construction. The manual was released in April at the annual
meeting of the American Association of Airport Executives, Lafrenz said,
and it met with a positive response: “It’s something that everybody
has always wanted but never had.”
A report: Improved Concrete Overlay Design Parameters for
Airfield Pavements. The report documents the development of an
experimental design for a large-scale, accelerated testing program at the
FAA National Airfield Pavement Test Facility to obtain performance data on
concrete overlays to support modern mathematical analysis methods.
A report: Innovative Rehabilitation of Pavement for Light-Load
Aircraft. The goal of this project is to prove that ultra-thin
whitetopping has a 20-year life cycle, Lafrenz says. In nine months, a
full-scale pavement section with UTW is being subjected to 20 years of
environmental wear — freeze-thaw cycles, hot and cold, wet and dry.
A project demonstrating the use of maturity meters for airport
pavement. Maturity meters are an electronic method of measuring real-time
strength gains of concrete as it cures. Instead of breaking beams to test
strength, the maturity meters use an electronic probe placed in the
concrete. The latest maturity meter can transmit by wireless technology to
a computer doing the strength readings; no wired connection is needed.
Under the fiscal 2002 program, the five projects awarded were:
- Innovative methods to test concrete in real time.
- A design guide for cement-stabilized bases.
- A project to document the planning and logistics needed to
accomplish a fast-tracked concrete airport pavement project.
- To develop criteria for the construction and measurement of
smoothness on airport runways.
- The fifth is a $200,000 field demonstration project, to be announced
at a later date.
Real-world results
“One of the unique things about our cooperative research program is
that neither the FAA nor industry runs it,” says Lafrenz. Instead, the
program is guided by an oversight group composed primarily of
representatives from the aviation industry. Organizations represented on
the committee include the National Association of State Aviation
Officials, Boeing Aircraft, the American Association of Airport
Executives, the American Society of Civil Engineers, the Airport
Consultants Council, and more.
“We’re using the money to produce real-world results that can
benefit the airport owner and operator,” says Lafrenz. “The oversight
group tells us what research they need to do their jobs.”
More projects
Other examples of projects in the FHWA Concrete Pavement Technology
Program include:
Traffic management — A contract was recently awarded to
demonstrate construction processes and traffic-management strategies aimed
at minimizing traffic disruption and highway-user delays caused by
long-life pavement construction. The project will involve surveys of
motorists and residents, pilot projects on urban highways, and the
documentation of planning and construction processes for such projects.
Compatible materials — Reliable tests are needed to predict
and avoid incompatibility of concrete materials that adversely influence
the fresh and hardened properties of concrete at early ages. This research
aims to develop practical test procedures and criteria to assess the
effects of combinations of materials on: early stiffening and excessive
retardation; potential for early-age cracking; and characteristics of the
air-void system.
Future research — A long-term plan is being developed to
provide focus and direction for concrete pavement research beyond the
current CPTP work and resources.
High-performance concrete — Various state highway agencies are
researching many aspects of HPC pavement. Topics include thin pavement
with polyolefin fibers; alternate dowel bar materials; various sealants or
no sealants; fiber-reinforced concrete pavement; low-volume road design;
super-smooth pavement; and many more.
Coefficient of thermal expansion — Development of a standard
test for CTE is underway with the testing of some 2,300 cores to be
completed during the next several years.
Non-destructive testing — Highway agency personnel are being
introduced to currently available non-destructive concrete testing
technology. At a pilot workshop in Maryland, in 2002, presenters discussed
information on a number of NDT methods for concrete: the maturity method
of strength testing; the pull-off bond test; the air void analyzer; and
the impact-echo test and concrete thickness gauge.
Performance related specifications — State highway agencies
will have guidelines for the development and use of PRS. Using this
approach, the measured acceptance quality characteristics for a pavement
— such as strength, slab thickness, and initial smoothness — are
related to pavement performance through mathematical relationships. DOTs
in Indiana and Florida are participating in PRS evaluations.
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Reprinted from Better Roads Magazine
August 2003 |
