C+S March 2021 Vol. 7 Issue 3 (web)

Expanded polystyrene (EPS) Geofoam (GF) is a rigid, engineered fill material that is widely known for its lightweight composition, predict- able performance, and simplified installation process. The effective fill solution is frequently employed by engineers and project designers to optimize labor resources, speed up construction timelines, and address a variety of geotechnical challenges, including: Supporting the Bottom Line: High-Performing, Engineered, EPS Geofoam as an Alternative Fill By Tom Savoy • lightening loads on structures, utilities, or underlying soils • remediating soft soils and minimizing differential settlement • stabilizing steep slopes and embankments • reduce lateral load behind retaining structures • serving as a structural void fill for concrete or landscaping applications EPS GF has been used as a geotechnical material since the 1960s. One of the first documented projects in North America that utilized EPS GF was during the installation of the Trans-Alaska Pipeline. Thanks to its thermal insulation properties, EPS GF was employed to provide effective utility protection. Decades later, it’s still being successfully utilized in the field. Just a few years ago, the rigid foam material was used to accelerate construction timelines and effectively stabilize the eastbound lanes of U.S. 36 between Boulder and Denver, Colorado. The material’s lightweight composition made it possible for crews to quickly unload over 200 flatbed trucks and install the product with ease. More recently, engineers and architects utilized EPS GF to build up a quarter-mile bridge across Tampa Bay that leads to the newly renovated St. Pete Pier waterfront park on Florida’s West Coast. The lighter load reduces settlements and boosts stability against bearing and slope failures to successfully support the largest waterfront park in the Southeast region. Project cost-savings, galore In application, EPS GF’s combination of lightweight yet load-bearing properties can support overall project cost-savings. For example, the geosynthetic fill’s lightweight composition lends a quick, ef- ficient installation process, which in turn can reduce hours spent on the jobsite. While lightweight, the rigid foam material is engineered to demonstrate exceptional compressive resistance to support high loads. With this level of brawn, one flatbed of custom-made EPS GF can accomplish what would otherwise require approximately 12 dump truck loads of soil fill. Less material in play helps simplify construction logistics, minimizing labor and material costs in twofold. Thoughtfully engineered to maximize efficiencies, EPS GF’s lightweight composi-

Geofoam swimming pool

tion, compressive strength and customization capabilities can support generous cost-savings across a project’s bottom line. Lightweight performance Adefining feature of EPS GF is its lightweight composition. Composed of 98 percent air voids by volume, EPS GF weighs approximately 0.7 to 2.85 pounds per cubic foot. It’s approximately 100 times lighter than most soil types, and 20 to 30 times lighter than concrete. This extreme difference in unit weight is the defining feature of EPS GF, making it an attractive solution over traditional fill materials. Because EPS GF is so lightweight, large earthmoving equipment is not required during in- stallation. Instead, custom-cut blocks of EPS GF can be installed easily and efficiently by hand—an ideal solution for accelerating construc- tion schedules. Because the pieces of rigid foam are designed to lock in place, much like stacking blocks or assembling a puzzle, smaller crews are freed up to focus on other, more time-consuming tasks on the job site. In application, the material helps keep projects on budget by decreasing upfront material costs and reducing the number of hours crews spend on the job site. As mentioned earlier, EPS GF’s lightweight composition was a defin- ing feature for the St. Pete Pier project engineers and designers, who were able to apply 700,000 board feet of the rigid foam material across the concrete deck of the bridge. Because the material is so lightweight, there is significantly less stress applied to the underlying substrate. “It’s a quarter-mile deck over water, and you don’t want additional weight over water,” said Dave Hall, a territory manager for Insul- foam, the leading manufacturer of EPS products. “Ground with soft soil makes building construction notoriously difficult. If you place something heavy on soft soil, it will place pressure on the underlying soil. The soil will inevitably compress with time, putting the structural integrity of the system at risk.” To its benefit, lightweight blocks of EPS GF can sideline this problem and lighten the load on the substrate. What’s more, the material is also designed in such a way that it does not degrade—a key factor to with- standing Florida’s low sea levels and high precipitation rate. Strength to boot Although lightweight, EPS GF is designed to exhibit exceptional strength. As an engineered material, manufacturers can customize EPS



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