Construction crews are rebuilding the ramp to southbound I-15 by placing 3,000 geofoam blocks. Once in place, a concrete slab is poured on top to evenly distribute the load of the ramp pavement and concrete walls are installed along the sides.
(UDOT photo)
Crews working for the Utah Department of Transportation (UDOT) are using geofoam blocks — similar to the Styrofoam used in packaging materials and ice chests — to build a freeway ramp that will connect the future West Davis Highway with southbound I-15 in Farmington.
These blocks allow crews to build the new ramp in close proximity to I-15 as well as the Union Pacific Railroad and Utah Transit Authority tracks without causing additional shifting or settlement.
Farmington Bay Constructors (FBC) is the general contractor on the large complex project. They are a joint venture of Ames Construction, Wadsworth Brothers Construction and Staker Parson Materials and Construction.
"Sometimes there are unique challenges on our projects, and they require innovative solutions," said Rex Harris, UDOT project director of the West Davis Highway. "Geofoam is another tool in our toolbox to efficiently build the roads, trails and bridges we all need to get where we want to go."
The ramp to southbound I-15 is being built with approximately 3,000 geofoam blocks. Each one weighs approximately 200 lbs. and measures approximately 4 ft. by 5 ft. by 9 ft. The blocks are brought to the construction site and then either placed as-is or cut to fit as needed. Once all the blocks are in place, a concrete slab is poured on top to evenly distribute the load of the ramp pavement and traffic, and concrete walls are installed along the sides.
The weight of using dirt to build the ramp would cause the ground underneath to settle anywhere from several inches to a few feet. This settlement is typical in construction and engineers accommodate this settling with their designs. However, in this case, the close proximity of the existing interstate and rail lines meant they could be negatively affected by typical settling.
UDOT is one of a handful of state transportation departments in the U.S. with extensive experience using geofoam. Some notable projects that also used geofoam include the I-15 reconstruction in Salt Lake County prior to the 2002 Olympics; the 1100 South bridge over I-15 in Brigham City; and the 5600 West bridge near 700 South in Salt Lake City.
Geofoam in Utah
UDOT previously emplored the use of a similar product when it upgraded the Union Pacific railroad in 2020. At the time, it marked the largest installation of geofoam ever used in the state and may be among the largest in the United States.
UDOT opted to go with the geofoam first and foremost for its light weight. The light weight prevented the sewer line from collapsing.
The geofoam also saved a significant amount of time in completing bridge construction on the project. Because soil at the site was soft, the contractor would have had to load the soil with surcharge — placing additional material on the existing ground — building it as high as the embankment, adding even more weight to speed the process along. The surcharge would also have to be drained, adding additional cost.
Geofoam allowed no additional weight on the soils below, and it doesn't settle like dirt does. There is no additional weight on the sewer line below or native soils below, so no compression causing settlement. The contractor took out enough heavy dirt and replaced it with super lightweight geofoam.
Crews installed the 112,000 cu. yds. of Geofoam, supplied by Oracle and manufactured by Atlas Molded Products, using a 60-ton crane and forklifts.
Geofoam History
The material was first used in road construction in Oslo, Norway in 1972. According to the Geofoam Research Center at Syracuse University (GRC), geofoam can be recovered from previous construction sites and reused.
After more than 20 years, geofoam was exhumed from a project and proved to be in good condition. The blocks exhumed were reused in another project.
Geofoam also can be shredded and formed into new blocks or sheets at the end of its life. According to the GRC, the process of recycling it does not involve chemical processing.
The GRC also said that geofoam is not biodegradable, but when it is installed underground, it does not have adverse impacts on soil or groundwater.
The use of geofoam has shown reduced environmental impacts. Geofoam, unlike soil, does not need to be compacted, shortening project timelines. Shorter project timelines mean less pollution from traffic slowdowns and construction vehicle activity.
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