Boston Logan becomes the first US airport to use 'green' asphalt on a runway repaving project
Boston Logan International Airport's Runway 9/27
Wed 28 Aug 2008 – The Massachusetts Port Authority (Massport) has committed to a $6.3 million project to mill and repave the outer edges of Runway 4R/22L at Boston Logan International Airport this autumn using a ‘warm mix’ asphalt that is produced and poured in a manner that reduces greenhouse gas emissions and energy use. If the mix performs as expected, it will be used to repave all of a second runway.
The asphalt is heated to between 250 and 275 degrees F, some 75 to 50 less than traditional ‘hot mix’ asphalt, resulting in a saving of nearly 2,000 tons of carbon dioxide on the project, according to Massport, and produce an energy saving of 26.4 billion BTUs. Another environmental benefit is that up to 20% of the new asphalt will be made from recycled asphalt.
“Warm mix uses 20% less energy to make, produces 20% fewer greenhouse gas 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’s CEO and Executive Director.
Because warm mix asphalt is not heated as high, the work environment is better for the crews installing the new pavement. Thermal and air emissions are lessened both on site and also at the Aggregate Industries production plant in Saugus, MA, where the manufacturing process reduces dust and NOx emissions.
The warm mix asphalt compacts better, says Massport, allowing for sturdy runways that can withstand the impact of heavy aircraft and high-pressure tyres. Traditionally, runway projects at Logan require that asphalt is laid in 3-inch thick sections called ‘lifts’, whereas warm mix allows for 6-inch thick lifts, which will shorten the time the runway is out of service.
Due to the stringent standards required for runway paving, the warm mix was first tested under FAA supervision on a taxiway and apron areas of the airport before permission was given to use it on the runway. Massport is hoping the warm mix will last twice as long as traditional asphalt, despite the effects of cold winters and warm summers at the airport.
Warm mix asphalt has been used at airports in South Africa, South America and Europe, including Frankfurt.