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Think back to the last flight you took. You’re sitting in a window seat, headphones in, as the plane begins taxiing onto the runway. The flight attendants go through their safety briefing, but you’ve heard it all before, so your mind drifts. You’re ready to relax, maybe take a quick nap. Just before you close your eyes, you catch a glimpse out the window as the plane accelerates, and the pavement and runway markings blur beneath you. You probably don’t give the pavement types much thought—it’s just part of the routine. But the pavement under those wheels plays a crucial role in ensuring a safe takeoff every time.
Runway pavement types are a vital part of airport infrastructure, evolving significantly since the days of early airliners like the Douglas DC-3. Where once a flat, open space was enough, today’s runways are engineered to handle modern aircraft’s weight, speed, and volume of traffic. In this post, we’ll explore the two primary pavement types used in runway construction, innovations in pavement design, and how Avion effectively cleans both.
When designing a runway, engineers select the pavement type based on factors like local material availability, expected aircraft traffic, and construction costs. The two main pavement types used around the world are flexible pavement and rigid pavement.
Flexible Pavement
Flexible pavement consists of a multi-layered structure. The base layer is a prepared subgrade, followed by a granular layer, and finally a top layer of asphalt. This structure is designed to flex and bend under the weight of aircraft, distributing the load through the layers beneath. It’s more adaptable to the weather and is easier and faster to repair, with a curing process that minimizes runway downtime.
However, flexible pavement has some drawbacks:
- Fuel sensitivity: Asphalt surfaces can be damaged by exposure to aircraft fuel, which is why aprons and idle areas are often constructed using concrete.
- Lifespan: Typically, flexible pavement lasts about 10-15 years and requires more frequent maintenance than rigid pavement.
- Edge weakness: The edges of flexible pavement can be susceptible to damage, requiring additional support.
That said, it’s ideal in climates where freeze-thaw cycles are a concern because it resists cracking from ice formation.
Rigid Pavement
Rigid pavement is constructed with a concrete slab over a granular sub-base. Unlike flexible pavement, it doesn’t bend under load; instead, it absorbs the pressure of aircraft. The joints between slabs help manage thermal expansion and prevent cracks, but they can increase construction costs.
- Longevity: Rigid pavements last longer—about 30 years—and require less frequent maintenance.
- Strength: The concrete surface is resistant to fuel spills and has stronger edges, which don’t require curbs or supports.
- Durability: This makes rigid pavement ideal for airports that experience high traffic from heavy aircraft or that are located in extreme climates.
While rigid pavement can be more expensive upfront, its long-term durability often makes it a more cost-effective option over time.
Innovations in Runway Pavement Types: Performance-Engineered Mixtures (PEMs)
Historically, pavement was assessed by its slump, air content, and compressive strength—measures that didn’t always correlate with its long-term performance. Engineers now use Performance-Engineered Mixtures (PEMs) to overcome these limitations and extend pavement lifespan.
PEMs involve carefully selecting materials, gradations, and additives to optimize the pavement’s performance based on the expected conditions. Rather than following traditional recipes, PEMs are designed to meet specific performance criteria, like resistance to cracking, moisture damage, and rutting, making them more durable, cost-effective, and environmentally sustainable.
Why PEMs Matter:
- Durability: PEMs improve the durability of pavements, reducing the need for frequent repairs and increasing longevity, which is especially crucial for airports.
- Cost-Effectiveness: Although PEMs may have higher initial costs due to advanced testing and materials, the reduced maintenance and longer lifespan make them more cost-efficient in the long run.
- Sustainability: PEMs often incorporate recycled materials and innovative additives like polymers and fibers to enhance durability and environmental friendliness.
For example, Denver International Airport uses PEMs to ensure its runways can handle extreme temperature fluctuations and heavy traffic. The airport’s pavement mixture includes polymer-modified asphalt and recycled materials, giving it superior resistance to rutting, cracking, and moisture—conditions that are especially tough in Denver’s hot summers and cold winters. This design has also improved the surface texture, ensuring skid resistance for many years with minimal resurfacing.
PEMs are particularly valuable at military airfields, where runways must endure intense forces from vertical takeoff and landing (VTOL) aircraft, which can direct engine blasts at the pavement.
How Avion Works on Different Pavement Types
Now that we’ve covered the differences between flexible and rigid pavement types, you may wonder how runway maintenance, particularly rubber removal, affects these surfaces. That’s where Avion comes in.
Avion is specifically designed to work on both pavement types without causing damage. On flexible pavement, the detergent is gentle on the asphalt binder, helping preserve the surface’s integrity during rubber removal. On rigid pavement, which is more chemically tolerant, Avion is equally effective, efficiently breaking down rubber deposits.
Because Avion relies on standard snow removal equipment for mechanical agitation, it provides a safe, non-invasive alternative to high-pressure water blasting, which can degrade runway texture over time. By using Avion, airports can extend the lifespan of both flexible and rigid pavement types, maintaining the necessary surface friction for safe takeoffs and landings without resorting to more aggressive, damaging cleaning methods. The formula is also environmentally friendly, made with 100% EPA cleangredients.
When it comes to preserving your runway investment and ensuring long-term performance, Avion is your trusted partner in rubber removal.
Further Reading
Sure Seal Website – Difference Between Flexible And Rigid Pavement
Encyclopedia Britannica – Runway Pavements
NCDOT Research & Development – Performance Engineered Concrete Mixtures