for DIA’s existing Automated Guided Transit System, which will one day connect to future Concourses D and E. “The use of Geofoam was as a long-term but still temporary fill mate - rial within the future opening of the new tunnel,” says Heekin of the need for a lightweight yet structurally stable material that could be cost-effectively installed now and removed at a much later date. At approximately 1/100th of the weight of soil, Geofoam’s dimensional stability makes material behavior resolutely predictable. Atlas manu- facturers Geofoam blocks in compressive resistances ranging from 2.2 – 18.6 psi at one percent deformation. “We installed 940 Geofoam blocks that were eight feet long basically by hand. There were very few waste cuts,” continues Heekin. While the logistics of accessibility were similar to those faced at SLC, the big difference on the DIA project is the Geofoam blocks are intended to be removed in the eventual next phase of tunnel construction. “Right now, the Geofoam is sitting on a ten-inch structural slab. When the tunnel extension continues, all the Geofoam blocks will be taken back out completely intact and could even be reused,” says Heekin. Like his contemporary in Utah, Heekin has experience working with Atlas Geofoam to address a wide range of architectural challenges on projects of many sorts and understands the possibilities are virtually endless. “We have used Geofoam to create exterior terraces, outdoor seating, stair configurations, and lots of other applications requiring a light - weight fill,” finishes Heekin. “In commercial construction, new and challenging situations arise almost every day. Atlas Geofoam is a dy- namic building material that cost-effectively solves a lot of architecture and engineering challenges.”
just-in-time delivery whenever needed,” says Outsen of the company’s capacity to support projects with practical logistical assistance. At SLC, once the Geofoam block and rebar grid were in place, Outsen and the RLWteam poured the concrete walls directly within the Geofoam formwork, which remains structurally integral to the finished platform. Justin Heekin also enjoys a challenge. He is a project manager with GH Phipps Construction Companies in Denver, CO, focused on concrete for much of his 25-year career. A Front Range Colorado and Wyoming Contractor, GH Phipps has deep roots in public projects spanning from education to transportation and many in between including recent work at Denver International Airport (DIA). “GH Phipps is committed to building relationships and giving back to the community in everything we do,” says Heekin. In addition to self- performing concrete on all their projects, GH Phipps also frequently subcontracts concrete services to other local, non-competitive contrac- tors. “Our work at DIA reflects our expertise and versatility in concrete. We are providing concrete services on four different concourses as a subcontractor to two different teams of general contractors.” Like their contemporaries in Utah, DIA is also thinking ahead and using molded polystyrene Geofoam fromAtlas to help future-proof facilities. As part of the closing stages of work on the existing Concourse AWest, Heekin and the GH Phipps team built the entrance to a tunnel extension
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csengineermag.com
DECEMBER 2021
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