Prototyping
IPRF working group progress report
by Jim Lafrenz
The Innovative Pavement Research Foundation (IPRF) has initiated eight separate research projects to investigate the optimum design and most efficient construction of concrete airport pavements. Here’s an update on its progress.
The IPRF is a non-profit applied research organization jointly spon-sored by the American Concrete Pavement Association, the Portland Cement Association, and the National Ready Mixed Concrete Association, It was begun in 1997 to provide applied research, technology transfer and implementation, and public educa-tion for concrete pavements.
Addressing the concerns of air-port owners and designers, the research seeks to provide much-need-ed guidance for smaller airports strug-gling to upgrade their facilities to meet increasing demand. AIR-21 pro-vided the funding; IPRF research is providing the tools to best utilize the money. Very specific technical infor-mation generated by this research will help owners and designers make informed decisions on pavement selection, design, and construction.
The first three of these IPRF proj- ects are nearing completion. Due out in October 2002, a "best practices" manual will provide contractors and design engineers with guidelines for constructing concrete pavements effectively. This publication is the first to set specific standards for airport pavement design and construction.
It will give airport owners insight into the challenges facing designers and paving contractors at airports today, and ensure that the people they hire adhere to the most up-to-date standards, guaranteeing the greatest return on investment.
Available in July 2002 will be a full-scale test plan for concrete pavement overlays. In many cases, a four-inch-plus concrete layer over existing con-crete or over asphalt is a cost-effective and long-term solution to airport pavement rehabilitation. As part of a total pavement management system, overlays can be a useful tool in the airport owner’s box. This tool will even-tually be used to refine overlay design techniques and overcome 1950s tech-nology.
ULTRA-THIN WHITETOPPING
In hopes of seeing ultra-thin whitetopping (UTW) approved for airport use by FAA, the IPRF is demonstrating its viability through documentation of various UTW proj-ects at airports around the country. UTW is a 2-1/2 inch to four-inch layer of concrete placed over an existing asphalt pavement. Research demon-strates the long-term durability, low maintenance, high load capacity, and economy of UTW for the airports.
The first phase of this project is completed and provides an initial assessment of UTW’s durability. The second phase will be an accelerated environmental durability (freeze-thaw cycling) study that further evaluates UTW performance. The success of this study and subsequent FAA approval will open up opportunities for UTW in the airport market.
NEW PROJECTS
The success of these first three projects led to the development of five new research projects, begun in May. The goals of these projects are:
• Improve acceptance criteria for accelerated construction. Research-ers are examining the technology that determines when concrete can be opened to traffic. Proper testing methods will speed construction time and improve efficiency. Research is evaluating innovative testing tech-niques to improve the acceptance cri-teria used in FAA specifications through field sampling, side-by-side testing, performance studies, and sta-tistical analysis of existing standards testing results. Researchers will then make recommendations for changes to FAA Advisory Circulars.
• Test these innovative accept-ance techniques. Researchers will conduct full-scale pavement testing using the plan developed in the 2001 research program.
• Recommend design criteria for stabilized and drainable bases. Researchers are compiling all current criteria used to select the qualities and characteristics of both base types. They will make recommendations for design criteria to incorporate the base into a balanced pavement design that best fits specific needs of an airport.
• Improve the efficiency and effectiveness of the technology for measuring the smoothness of airport pavement. Researchers will test vari-ous methods such as the traditional straightedge and the California Profilograph to determine the best fit for airport pavements. The research will calibrate all the techniques to a common measurement system, select pavement construction acceptance criteria for each technology, and make recommendations for adoption of the criteria by the industry.
• Document many successful fast-track airport paving projects from around the country to provide air-port owners with valuable procedures for accelerated construction drawn from real-life experience.
