Boston airport tests warm-mix asphalt

BOSTON—Logan International Airport will be the first airport in the nation to use warm-mix asphalt on a runway repaving project, following a vote in July by the Massachusetts Port Authority Board to spend $6.3 million on the work. Warm-mix’ asphalt is heated to between 250° F and 275° F, about 75° to 50° F less than traditional hot-mix asphalt. According to the Massachusetts Port Authority (Massport), which operates the airport, using warm mix on this project will result in the reduction of nearly 2,000 tons of carbon dioxide, savings of about 200,000 gallons of diesel fuel, and produce an energy savings of about 26.4 billion Btus. Another environmental benefit is as much as 20 percent of the new asphalt will be made from recycled asphalt.

"Warm mix uses 20-percent less energy to make, produces 20-percent fewer greenhouse emissions when applied, and allows us to use a higher percentage of recycled asphalt pavement in the final product,’’ said Thomas J. Kinton Jr., Massport CEO and executive director.

Warm-mix asphalt has been used at European airports. Runway paving projects in the United States must meet stringent Federal Aviation Administration (FAA) standards. The warm mix was first tested at Logan on a taxiway and apron areas with FAA oversight before the airport received permission to use it on a runway.

The runway is 10,005 feet long and 150 feet wide. The repaving contract calls for the outer 37.5 feet of each side of the runway to be milled and repaved. If the warm mix performs as expected on the outer edges of the runway, then it will likely be used for the next runway repaving project, which calls for all of Runway 9/27 to be repaved.

Because warm-mix asphalt is not heated as high, the work environment is better for crews installing the new pavement. Thermal and air emissions are lessened both on site and at the plant where it is produced. The manufacturing process also reduces dust and NOx emissions.

Additionally, warm-mix asphalt compacts better, allowing for sturdy runways that can withstand the impact of heavy airplanes and high-pressure tires. Traditionally, runway projects at Logan require that asphalt is laid in 3-inch-thick lifts; warm-mix asphalt lets workers lay down the pavement in 6-inch-thick lifts, which will shorten the time the runway is out of service.