A variety of challenges arose for the design of Citrus Tower Corporate Plaza in Riverside, Calif. The large office building stands on a high profile corner location near a major highway. As a result, the owner's goal for the aesthetic design was to "create a memorable architectural statement that was a friendly neighbor to the community, with 'traditional' quality architecture to which no one would be indifferent," says Herb Nadel, principal at Nadel Architects.

GFRC was chosen for the project due to its capabilities in achieving the multi-hued look that was desired and its light weight. The building's foundations are set above a four-story subterranean parking structure on a post-tensioned slab, which required the above ground structure to be as light as possible. But the designers also wanted to use precast concrete materials to maximize longevity and durability.

Several other options were considered, including stone, 4-inch thick precast concrete panels, and exterior cement plaster. All were intended to provide a stone like appearance to meet the owner's requirements, Nadel explains. Evaluations showed that GFRC would meet all of the needs, providing a similar appearance to what precast concrete could provide while eliminating some of the necessary weight. The GFRC's light weight also allowed a reduction in some of the structural steel framing being used, saving costs.

The ability for the GFRC components to cast multiple colors in one panel also provided budget savings. Using the various colors required close pre-planning with the precaster to ensure clear transitions between colors. In all, three mix designed were created, with some panels including all three. Two finishes, light and heavy sandblasting, also provided textural variety. The granite attachment to the panel is achieved by spraying a thickened GFRC back-up skin to the back side of each granite piece. Additional GFRC is consolidated to cover metal clips that attach to the granite.

The building's most dramatic feature is the rounded tower on the corner, which extends past the roofline. Its canopy consists of compound radius GFRC panels, with granite cladding the topmost band. The design reflects a similar project that was to be designed by Nadel in Riverside. "We showed this idea to the client, and we thought the city might be receptive to this idiom of architecture because it blended so well with other structures throughout the city," Nadel says. "The curved corner becomes a beacon and a very identifiable form, giving the building distinctive characteristics along with natural colors that reflect the general built environment."

The designers worked closely with the precaster to find the proper mix of colors and textures. Full-size mockups of the panels were created to confirm the choices. "Those crystallized our selections, and the process of creating them was very successful," he says. Working with the GFRC panels was seamless, he notes. "Its flexibility created forms and shapes as needed and worked well with the window system. The needed shapes were easily achieved. Detailing the panels was also a simple process, since the material can be configured in virtually any shape or form because of its plasticity."

The GFRC offered a great option for this project, he says. "As far as I'm concerned, working with GFRC, or precast concrete, is a fairly simple design process. We have used it innumerable times. I would highly recommend the use of this material because of the design excellence that can be achieved at a very economical price." The community agrees that the project fits well into the neighborhood and provides a dramatic, signature style. "We have been repeatedly told that the building is a beautiful addition to the city," he says. "It is compatible, memorable, and has an excellent standard of quality. It has raised the bar for architectural excellence within this community."