The National Asphalt Pavement Association is working with the Federal Aviation Administration to turn pavement research into practical tools airports, contractors and consultants can use in the field.

Through the Airport Asphalt Pavement Technology Program (AAPTP), the association is studying everything from asphalt mix design and recycling to high-speed taxiway exits, pavement inspection technology and construction practices.

Richard Willis, vice president of engineering, research and technology for the National Asphalt Pavement Association (NAPA), and Brett Williams, a member of NAPA’s engineering team, recently joined the AviationPros Podcast to discuss the program, the challenges facing airport pavements and how emerging technology could change the way airfields are designed, constructed and maintained.

Listen to the podcast here. 

AviationPros: For those who aren't familiar with the Airport Asphalt Pavement Technology Program, what is it?

Richard Willis: The AAPTP is a cooperative agreement between NAPA and the FAA. As part of FAA reauthorization, Congress gave the FAA $6 million a year to advance pavement technologies. Three million dollars goes toward the asphalt industry and $3 million toward the concrete industry.

The purpose is to advance asphalt pavement in terms of design, construction and materials, and to find solutions to problems people are experiencing in the airfield community. That could be contractors trying to build airfields or owners and consultants trying to make pavements last longer or solve problems they're having.

One thing that makes the program different is that while we're doing research and trying to find solutions, we're also heavily focused on implementation. We don't want it to end up in a PDF or a report. We're creating tools and value for airfield users that can actually help them solve problems.

AVP: How do you decide which pavement challenges to research?

Willis: Anybody is allowed to come to us with ideas. A couple of times a year, a group called the Program Coordination Group takes those ideas and prioritizes them.

The group includes an asphalt contractor, the FAA, the Department of Defense, Boeing, the aggregate industry and state asphalt pavement associations, among others. NAPA manages the group, but our staff doesn't have a vote on which projects are recommended to the FAA.

Projects can range from construction and new materials to websites, apps and efforts specifically focused on implementing the research and getting information into people's hands.

AVP: What are some of the biggest pavement challenges airports are facing?

Brett Williams: We've had projects looking at balanced mix design and how we design mixes to improve performance and get more life out of our facilities. We've looked at recycling efforts and technologies that are being used on highways and roads, resilience of asphalt pavements at airfields and the design of high-speed exits.

We've also developed resources such as the Asphalt Paving Handbook to help people across the industry understand how to best build pavements on airfields.

The challenges can involve materials, design or operations. We're taking input from all different parts of the industry, and we really look to the airport community for that feedback. If you're experiencing challenges or see opportunities, we want to hear about them.

Willis: That's one of the great things about the program. It's the entire industry coming together to find solutions. A lot of research might otherwise be done by an owner or contractor trying to figure something out individually. Here, consultants, owners, the FAA and contractors are coming together to help solve each other's problems.

AVP: Implementation seems to be a major part of the program. How are you making research useful to people working in the field?

Williams: That's a big piece of it. You could almost say the actual deliverable isn't the research. It's bringing these things into the field and driving implementation.

The Asphalt Paving Handbook, for example, started as a project to develop a PDF. It's a big resource, around 400 pages, and we all know sitting down to read a 400-page resource probably isn't going to happen when you're working in the field.

The next phase was developing an app and website where people can access that information. It has an AI feature that allows users to ask questions against the resource and directs them to the information they're looking for.

We've also developed videos, fact sheets, webinars and other tools. One example is a design tool that helps pavement designers make sure they're selecting the correct asphalt binder grade. We're looking at different avenues to get this information out and actually get it used.

AVP: Tell us more about that binder selection tool. What problem does it solve?

Willis: We had contractors coming to NAPA saying they were getting consultants specifying binders that simply didn't exist. They might not have a strong background in asphalt binder and rheology, while the FAA has a pretty prescriptive specification for selecting an asphalt binder.

The research team at the National Center for Asphalt Technology at Auburn University determined the base binder grade for every county in America. No matter where your airport is, we know the starting point.

Someone can go into the free, web-based tool, select the airport and walk step by step through the FAA specification by answering questions. At the end, it tells you the binder you need to follow the FAA specification. It can also do the same thing using Department of Defense specifications for military airfields.

It takes a lot of the guesswork out of the process, especially for someone who doesn't have a strong background in asphalt binder.

AVP: For those of us who aren't pavement experts, what exactly is an asphalt binder?

Willis: The asphalt binder is what coats the rocks and holds the asphalt mixture together. It's what's called a viscoelastic material, which means it reacts to how long a load is on it and the temperature at which it's being loaded.

The way I describe it is that it's a lot like Silly Putty. If you make a ball of Silly Putty and throw it at the ground, it's going to bounce. But if you take the same Silly Putty, put your thumb on it and apply pressure gradually, your thumb will slowly sink into it.

That's important at airfields. On a runway, the load might be heavy, but it's moving fast. On taxiways and aprons, that load can sometimes just sit there. You need a binder that's able to resist that.

We also have to account for temperature. At high temperatures, we're concerned about rutting or deformation. At very low temperatures, asphalt can become more susceptible to cracking. Binder specifications therefore account for the climate of a particular location as well as the types of loads the pavement will experience.

An asphalt binder used at Miami International Airport is going to look very different from one used at Seattle-Tacoma International Airport simply because of the location.

AVP: Workforce development is a challenge throughout aviation. How is the program helping educate the next generation of pavement professionals?

Williams: Making the Asphalt Paving Handbook available in the field gives people with less experience a resource when they encounter something they haven't seen before.

The videos developed from the handbook have also been incorporated into different training programs. We've translated both the audio and visuals into Spanish so that material is accessible to Spanish-speaking workers as well.

There are opportunities to participate in project technical panels and work alongside researchers. A number of projects are also led by universities or involve multiple universities, so graduate students and research assistants are learning about the challenges facing the industry and helping develop solutions.

There are a lot of different ways we're trying to build that learning experience for the next generation.

AVP: What emerging technologies could have the greatest impact on airfield pavement design, construction and maintenance?

Williams: We had a project specifically looking at advanced technologies for airfield pavement projects. Researchers used artificial intelligence to digest more than 10,000 papers and narrow that down to technologies that could potentially be used on airfields.

Some are technologies that aren't widely deployed at airports yet, such as balanced mix design and recycling. Others include high-modulus asphalt pavements, innovative products for fuel resistance, e-ticketing for material delivery and thermal profiling during construction.

Longer term, there are technologies such as drone-based inspections and ground-penetrating radar that could give us more information about pavement condition.

There are a lot of technologies that could help us improve quality, better understand our materials and prepare airports for the future.

Willis: One important thing to remember is that airports implement technology more slowly than highways, and there's a reason for that. It's a higher-risk environment. We have to make sure things such as foreign object debris don't get into aircraft and cause problems.

One of the valuable things about the AAPTP is that it can help de-risk innovation by doing the legwork and helping airports understand what's viable and what isn't. Sometimes we'll partner with the FAA's research facility in New Jersey and build test sections with new materials we're evaluating.

People shouldn't have to experiment with these things on their own runways. Runways aren't great places for experiments. This program and its partnership with the FAA can help airports determine what works before they put it into operation.

AVP: What would you like airport leaders to understand about investing in pavement research and innovation?

Willis: When you compare the cost of research to the cost of an asset, research pales in comparison. It's important to do this legwork so airports can have confidence that an asset is going to perform when they're trying something new.

One of the strengths of this program is that we're trying to leverage the research nationally. For example, we're doing a project on improving or maintaining longitudinal joints, and that's something that applies to airports across the country.

We're not developing things in isolation for one or two places. We're trying to solve national issues, improve specifications and make pavements last longer.

We also recently launched a monthly newsletter, From Research to Runways, to share what we're learning and help airport professionals put that research into practice.

I'd also encourage airport leaders to reach out when they're having problems. We're always looking for new ideas. We're not trying to come up with things that simply sound interesting. We're trying to solve real-world problems.

That's how our work on plastic flow at high-speed exits began. Airports told us they were seeing asphalt deform where aircraft were turning quickly and creating high shear forces. That gave us a real-world problem to investigate and develop potential solutions for.

That's what we want the program to do: hear what people are dealing with on a day-to-day basis and find ways to help solve it.