Airport Runway Surfaces: Asphalt, Concrete, and Gravel

This short article discusses the three main types of surfaces used for airport runways!

Asphalt

A mixture of crushed stone, gravel, sand, and bitumen (a petroleum byproduct that binds asphalt together), asphalt is the world’s oldest runway material. Due to its flexibility, asphalt can withstand expansions and contractions due to varying temperatures. Thus, asphalt runways rarely experience cracks and need minimal repair. Asphalt is also a relatively cost-effective substance that’s readily available all around the world, making it a great option for small airstrips and commercial airports alike.

Photo of Amsterdam Airport Schiphol, with all of its runways made of asphalt (Source: Velvet Escape)

Polymer-Modified Bitumen

Polymer-modified bitumen is formed by mixing polymers into the asphalt mixture. This practice reduces the surface’s tendency to crack and deform upon repeated use. Similarly to traditional asphalt, polymer-modified bitumen is substantially cheaper than concrete, making it a cost-effective option for high-traffic airports.

Porous Friction Course (PFC)

Many traditional runways require grooves to facilitate surface water disposal to prevent aquaplaning, and laying a porous friction course serves as an alternative. As suggested by its name, PFCs allow water to pass vertically through the material and then move horizontally clear of the runway.

(Source: Lehman-Roberts)

Concrete

Concrete is a mixture of cement, water, sand, gravel, and sometimes crushed stone. Concrete is much more durable than asphalt and can withstand damage from heavier aircraft and high-frequency operations. Although concrete runways are more expensive, they usually have lifespans of up to fifty years with proper maintenance, making concrete runways the go-to option for large commercial airports.

2 of the 4 concrete runways at LAX airport (Source: Terry Riley on Pinterest)

An image of Beijing Capital Int’l Airport, which features both concrete (top) and asphalt (bottom) runways.

Gravel

Gravel is less common than concrete or asphalt, but gravel runways are quite commonly seen on small airfields in the north. Aircraft need to undergo modifications to be certified to land at these airfields, such as Norlinor’s B737–200 Combi and many older 737s from Alaska Airlines.

A Boeing 737–200 landing on a gravel runway (Source: The Boeing 737 Technical Site)

Let me know if you have any questions!