An airfield pavement project at Philadelphia International Airport (PHL) is using approximately 90,000 cu yd of ultra-light foamed glass aggregate (UL-FGA), which officials believe is the largest application of its kind in North America. UL-FGA is made from 100% post-consumer recycled glass and is 85% lighter than quarried aggregate. The ultra-lightweight fill speeds placement and eliminates the need for piles. Rick Foster, Executive Vice President-James J. Anderson Construction Co. said work on the $35-million contract started late 2020.
He said, “It’s really a material replacement job. We’re digging out heavy material and replacing it with lightweight aggregate. The compaction efforts are significantly different than compacting typical aggregate. FGA is:
• Easy to move around
• Compacts with a dozer versus a roller
• Could shave a year off the job compared to using wick drains and surcharging”
The apron is expected to be completed by the end of 2021. The scope includes:
• 5,000 linear ft of storm pipe
• 62,000 sq yd of subbase
• 54,000 sq yd of 16-in. concrete pavement
• 8,000 sq yd of 9-in. concrete overlay
Larry Allen, Senior Project Manager-PHL, agreed that FGA helped cut the construction schedule. He said, “Since the airport is near the Delaware River, the conditions include a high water table and soft soils that have a high potential for significant settlement.” Surcharging, wick drains or other methods were considered, but, he added, “the use of FGA saved a minimum of six months on the construction schedule from the next fastest option, surcharging with wick drains.”
FGA has been used in Europe for [several decades], said Archie Filshill, Founder-AeroAggregates in Eddystone, Pa. (2012). The company is now opening two more plants.
To make FGA:
• Recycling centers send glass bottles of any size or color to the plants
• Converts them into the aggregate by milling them into a powder
• Mix it all in a foaming agent
According to a Federal Highway Administration (FHWA) report, one of the first major projects using FGA was an interchange reconstruction for the Rhode Island Dept. of Transportation. FGA ensured that the 100-year-old brick sewer at the interchange was protected against the weight of the embankment, with no settlement. Filshill said, on the airport apron replacement, using FGA diverts the equivalent of over 83 million glass bottles from landfills, and reduced delivery truck trips by 6,000. Moreover, crews can place 3,000 cu yd a day instead of the typical 1,000 cu yd, regardless of weather. FGA isn’t flammable or degradable, unlike other lightweight aggregates, typically styrofoams.
Foster said, “One of the challenges using FGA is that the material comes in 100-cu-yd trailers, so we have to be careful about access. I see it having multiple uses as far as ground improvements, loading critical structures. Due to its lightweight nature, at some point, this material can potentially change design concepts.”
For the Engineer Magazine (ENR) article titled “Philadelphia Airport Job Uses Lightweight Glass Aggregate”, please go to: https://www.enr.com/articles/51546-philadelphia-airport-job-uses-lightweight-glass-aggregate
PHOTO COURTESY AEROAGGREGATES