Pavement
Concrete Solutions
Progress report from ACPA’s Innovative Pavement Research Foundation
By Jodi Richards
October 2004
The IPRF (Innovative Pavement Research Foundation) was formed asa non-profit jointly by the American Concrete Pavement Association(ACPA), the Portland Cement Association (PCA), and National Ready MixedConcrete Association (NRMCA) for the purpose of unifying all the resourcesin the industry to perform applied research, according to Jim Lafrenz, ACPA director of airports and IPRF cooperative programs manager. In the few years since the foundation’s inception, great strides have been made and continue to be made with pavement.
Lafrenz explains that “applied research” means that a problem is identified in the field and the necessary research to answer the question or address the problem is performed. “So it’s not just research for the sake of research.”
All three organizations (ACPA, PCA, and NRMCA) can and do contribute monies to IPRF, “but the primary program has evolved into a cooperative agreement with federal agencies. The current cooperative agreement is with the FAA. And at this point in time, the total funds available for research are $8.3 million. That’s funded by Congress directly, not funded by FAA individually.”
There are some four hundred people involved with the research projects, and the ACPA, PCA, and NRMCA underwrite the overhead of IPRF “so there’s no overhead expenses involved; it’s strictly the time of the people that manage the program.”
According to Lafrenz, the 2004 program was just initiated and the 2005 program will not begin until an appropriation from Congress is received. “We don’t know when that will be,” he says. “The last two years it has been in February, so I’m not expecting anything right away, but we are looking toward a 2005 appropriation.”
Historically, says Lafrenz, Congress has appropriated $2 million per year. He adds that under Vision 100, Congress also put forth $2 million per year for the asphalt pavement industry.
Identifying a Project
Representatives from various industry associations, including the Airports
Consultants Council (ACC), the American Association of Airport Executives
(AAAE), the Airports Council International-North America (ACI-NA),
the National Association of State Aviation Officials (NASAO), the Department
of Defense, Boeing, the American Society of Civil Engineers (ASCE),
and ACPA make up the committee that brings research requirements forward
based upon their experiences through their own organizations.
Explains Lafrenz, “Each group brings projects forward, concepts for projects, or ideas for particular problems. They meet once a year and prioritize the work that needs to be accomplished. We accomplish the work in the priority they establish based upon the funds that are available.
“One thing unique about that is that neither the IPRF nor FAA can direct that board for what should be done/what should not be done. They act as the agents for the oversite committee.”
Once a project is identified, says Lafrenz, a technical committee of three to five people “who are considered to have some expertise in the area we’re looking at” is put together. A request for proposal is then written and posted. “Anybody from academia to private industry to government agencies can submit proposals to accomplish the work,” he says. The research projects can take anywhere from 18 months to a couple years to accomplish, adds Lafrenz. Currently there are 28 individual projects underway.
Research Leads to Industry Itandards
Some of the projects that were started in 2002 are just now coming to
a close. Lafrenz expects to see reports on them early next year. One
of those is a design guide for how to use stabilized bases.
Explains Lafrenz, “Right now FAA requires concrete pavements that support aircraft that weigh in excess of 100,000 lbs. have a base. That stabilized base can either be cement-treated base, asphalt-treated base, or what they call cement-stabilized. There’s no construction guidance on how you design or build bases. We’ve seen, historically, sometimes you get a good one, and sometimes you get a bad one. So this design guide is going to establish the minimum standards for design and construction of stabilized bases for airport pavements. That will result in a considerable amount of savings as well as a substantial improvement in performance.”
Another project, of which a draft will be out in February, is on airfield pavement smoothness. Currently, says Lafrenz, FAA specifies a 16-foot straight-edge be slid down the pavement. If more than one quarter inch of daylight can be seen under the bar, the pavement is not considered smooth and it either must be removed and replaced or ground down. “It’s extremely labor intensive and expensive to have someone out there sliding this 16-foot straight-edge around the pavement,” he says.
The design guide and handbook will advise on appropriate airport pavement smoothness criteria and ways to measure it.
The best known document IPRF has come out with, says Lafrenz, is the Best Practices for Airport Concrete Pavement Construction (available at www.iprf.org), in circulation since April 2003. “It’s been widely adopted by the pavement industry, says Lafrenz, and translated into Spanish and we’ve started seeing it used in South America. The Canadians have picked up on it very quickly and started using it. We’re getting a lot of good comments because it’s the first document of its kind that actually addresses all the variables beginning from the time of design through the end of construction and how each one impacts the quality of the pavement.”
Demonstration Projects
IPRF has a separate research category called demonstration projects.
Lafrenz explains this category is for industry people who have an innovative
idea and want to apply to have a demonstration project accomplished. “What
it amounts to is the airport sponsor agrees to have the work demonstrated
at his or her airport. The contractor volunteers to use whatever innovation
it is, and IPRF pays for independent analysis and evaluation.”
One such demonstration which took place at Cleveland Hopkins was recently completed. “Industry has always been trying to solve the problem of dowel bars in concrete pavement,” says Lafrenz. “The traditional method and the slowest and most expensive, of course, is drilling the holes and then inserting the dowel bars individually using hand labor.
“There’s an industry that has developed what they call an insertable plastic sleeve. It’s a very thin plastic sleeve, just slightly larger than the dowel bar. They’ve developed a machine that will insert this; after the concrete’s hardened, you strip that plastic mold out, and your dowel hole is formed automatically. So you don’t have to do the drilling. You still have to do the dowel bar insertion, but the drilling is the most expensive part.”
Lafrenz says the demonstration project shows that higher production, better alignment, and better quality can all be obtained by using this plastic insert. “That’s a small project that costs less than $25,000 to evaluate, and yet could mean a paradigm shift in how we build pavements using dowel bars.”
A New P501
The IPRF is working with FAA to develop a construction specification
for concrete airfield pavement, which will be a new national standard,
says Lafrenz.
Lafrenz calls P501 the “FAA Bible” on concrete pavement construction. The document has not been updated since 1979, “other than a lot of patchwork,” he says. “We don’t like to call it a P501 rewrite, but it will be a new P501. That’s kind of unique the way we’re doing it because the technical bill is made up of people from those industries that use the specification.
“We have representatives from ACC, ASCE, ACI-NA, NASAO, FAA, ACPA; they sit as representatives on the technical panel. They are also responsible for carrying results back to their agency for review and concurrence, so that when we finish the work, probably November 2006, we will have an industry standard that the industry concurs with.”
Chemical Reaction Research
Another project that’s going to have significant impact in the airport
world, says Lafrenz, involves the testing of chemical reactions between
pavement deicing chemicals and concrete pavements. “In some cases
it’s deleterious, in some cases it’s minor. But we’re
looking at new testing procedures to test concrete pavement before their
construction for resistance to those chemicals.” In this particular
case, it’s potassium acetates, which were introduced to deicing some
ten years ago, that are causing damage. “The glycols themselves don’t
chemically react with concrete, but the potassium acetates have demonstrated
a significant chemical reaction potential.”
On a similar note, the organization has a study in progress to look at dedicated deicing facilities at airports across the U.S. to determine how they respond to the presence of chemicals that are used to deice airplanes and pavement.
Other Guidance
IPRF is also developing a Best Practices Guide for the Construction of
In-Pavement Lighting. Says Lafrenz, “Right now there’s no
guidance in the field as to how you design and construct in-pavement
lighting.”
A precision statement on the method of tests the FAA uses to determine the flexural strength of concrete is also under development with IPRF. That particular test, says Lafrenz, which is the FAA standard for acceptance for pavement, has never had a precision statement and it’s been used for over 30 years.
Says Lafrenz, “A precision statement is if I do the test and you do the test, what can I expect to be the difference in the answer? We’re looking at that in particular because a number of times we run into construction issues where there’s allegations that the concrete didn’t meet the strength requirement, but it actually did. What it boils down to is who did the test correctly, or what was the exact variability of the test.”
