Undertaking a 56-building compound is no easy task, especially when time is of the essence. The new Department of Defense Ft. Irwin Military Operations in Urban Terrain Training Facility used a unique concrete/steel hybrid to reduce the construction time in half, and minimize energy costs. The construction site situated in the Mojave Desert also posed an obstacle in maintaining a productive workforce facing extreme heat conditions.

General contractor RQ Construction Inc., Bonsall, Calif., chose a system that combines cellular precast concrete with cold-formed steel framework. These lighter panels helped reduce energy and labor costs. The precast panels are installed using teams of four and a forklift that would lift them into place. Each 2-inch panel achieves an R-value of 4 yet only weighs 60 to 70 pounds per cubic foot.

With typical concrete weighing 150 pounds per cubic foot, these lighter panels allowed the construction team to use smaller cranes then the typical panel would have needed. The foundation requirements also were less because of thinner panels, thus reducing the strength and size of the foundation needed to withstand the load of the walls. Again this reduces the amount of materials and energy required to build. The panels also hold up to wind and seismic forces, passing the Miami/Dade County Windblown Missile Impact Test.

Cellular concrete-which uses air bubbles in place of aggregate-requires less materials. It also increased the insulation value, while reducing the overall weight of the structure. The concrete mix includes Type I or II portland cement, Type F fly ash, and a foaming agent. Using steel framework, the cellular concrete is pumped into the pre-assembled panel frames. Each panel is labeled, and has the necessary holes and notches already in it. The framework also provides furring space for insulation, electrical conduits, and other utilities. Panels then are delivered to the jobsite for easy and efficient installation. The construction system can be used in multistory applications, up to six stories tall.

Less materials and thinner wall panels allowed for more usable space within the structure, thus reducing the building's overall carbon footprint. In addition, this energy-efficient construction method helped RQ Construction complete the project within six months, instead of the projected year time frame, because on average teams were enclosing a building a day. This freed up time for ancillary trades to access the structure and complete other elements of construction.

Project: Ft. Irwin Military Operations in Urban Terrain (MOUT) Training Facility
Owner: Ft. Irwin National Training Center
Architect: SEI Group Inc.
General Contractor: RQ Construction Inc.
Concrete Producer: Ecolite Concrete Inc.

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