Good as Gold

The Atrium in Victoria, British Columbia, Canada, is the first building in North America to use precast cladding made with ultra-high-performance concrete. The first floor houses cafes, and a full-height glass atrium opens the interior offices to daylight. The building's material and color palette complements its surroundings.

Precast panels are cast at the Lafarge Canada plant with ultra-high-performance concrete poured into ribbed forms. Mix designs consisted of cement, silica fume, ground quartz, sand, PVA fibers, and superplasticizer. The microscopic particles precisely replicated the form surface texture and profile. Vibration was not necessary to aid placement.

An assembled panel shows the cast-in surface pattern of vertical lines. The ultra-thin precast panels are set on a unitized curtain-wall assembly, which mated various components of the system together. Low mass of the lightweight panels made it possible to reduce the seismic forces on the support structure.

The thin profile of the high-strength UHPC precast panels contributed to an exterior building envelope thinner than would be possible with other cladding materials. This allowed space for a conditioned air supply chamber around the building's perimeter used as part of a high-efficiency, displacement air ventilation system.

With only minimal fiber reinforcement required for the highly dense precast panels, it was possible to create thin, complex, curved pieces to fit the design. Individual curved forms were used to manufacture the various radii. This technique created smooth curves and curve transitions.

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